Wmi Alhap Final Report 2007

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Alberta Hail Suppression Project 2007 Field Program Final Report Page: 2

Weather Modification Inc. November 2007

ALBERTA HAIL SUPPRESSION PROJECT

FINAL REPORT2007

Terry W. Krauss, [email protected]

Editor

A Program forSeeding Convective Cloudswith Glaciogenic Nuclei to

Mitigate Urban Hail Damage in theProvince of Alberta, Canada

by

Weather Modification Inc.3802 - 20thStreet North

Fargo, North DakotaU.S.A. 58102

www.weathermod.com

for

Alberta Severe Weather Management Society

Calgary, AlbertaCanada

November 2007
mailto:[email protected]:[email protected]


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EXECUTIVE SUMMARY

This report summarizes the activities during the 2007 field operations of the Alberta Hail SuppressionProject. This was the twelfth year of operations by Weather Modification Inc. (WMI) of Fargo, NorthDakota under contract with the Alberta Severe Weather Management Society of Calgary, Alberta. 2007was the second year of the third 5-year contract cycle for this on-going program. The programcontinues to be funded entirely by private insurance companies in Alberta with the sole intent to mitigatethe damage to urban property caused by hail.

The cloud-seeding project was made an on-going program in 2001 because the insurance losses dueto hail were approximately 50% less than expected during the first five-year contract period 1996-2000.Calgary and Red Deer have seen >30% increases in population in the last 10 years, however, thefinancial losses caused by hail have been less than the 10 year average before the start of the cloudseeding program in 1996. This is in spite of Calgary reaching a population of 1 million last year. Theproject design has remained the same throughout the period. The program was operational from June1

stto September 15th, 2007 and only storms that posed a hail threat to an urban area, as identified bythe projects weather radar situated at the Olds-Didsbury Airport, were actually seeded. The projecttarget area covers the region from High River in the south to Lacombe in the north, with priority given tothe two largest cities of Calgary and Red Deer. The target area was increased last year to include thetown of Strathmore and some of the smaller towns east of the QEII highway around Calgary which have

experienced rapid population growth.

Hail was reported within the project area on 34 days this past summer. Larger than golf ball size hailfell on June 10

thnear Rocky Mountain House and on the evening of July 15

thnear High River. Golf ball

size hail was reported on June 29th near Vulcan and July 30

th near Carstairs. Walnut size hail was

reported on five days (June 12, 14, 22, and July 23 and 24). It was an above average year for largehail.

For the entire Province of Alberta, the Alberta Agriculture Financial Services Corporation (AFSC) inLacombe reported hail damage to crops on 75 days (1 day in May, 23 days in June, 21 days in July, 23days in August, and 7 days in September). Golf ball size hail was reported to the AFSC on 9 days(June 19, 29, July 2, 14, 15, 23, 24, 29, and Aug 5) this summer. Data from crop insurance claimsindicates that crop damage in 2007 was above average. This was a bad summer for severe weather

across the prairies. Environment Canada reported multiple severe tornados on June 22 and 23, 2007near Elie Manitoba, including the first ever F5 severity tornado. No tornados were reported from anystorms while seeding, and our pilots did not see any tornados. In general, the weather in the projectarea this summer was cool and wet in June, and then hot and humid during July, and then relatively hotand dry in August. There was an above average number of days with temperatures > 30 deg C and thehumidity was very high in the second half of July which provided the atmospheric conditions for verysevere thunderstorms.

During this season, there were 76 aircraft flights totaling 115.2 flight hrs on 37 operational days. A totalof 41 storms were seeded during 38 seeding flights (85.8 hrs) on 21 days on which seeding took place.There were 10 patrol flights (14.5 hrs), 17 test flights (11.6 hrs), and 1 maintenance flight (0.4 hr). Theamount of silver-iodide nucleating agent dispensed during the 2007 field season totaled 99.7 kg:consisting of 1622 ejectable (cloud-top) flares (32.44 kg seeding agent), 413 end-burning (cloud-base)

flares (61.95 kg seeding agent), and 77 gallons of AgI-acetone solution (5.28 kg seeding agent). Therewere 10 flights (3.0 hrs) for public relations and media purposes.

The procedures used in 2007 remained the same as for the previous years. Three specially equippedcloud seeding aircraft were dedicated to the project. One Piper Cheyenne II and a Cessna 340A werebased in Calgary, and a Beech King Air C90 was based in Red Deer. The Calgary office and aircraftwere located at the Morgan Air hangar at the Calgary International Airport. A WMI Red Deer office wasset up in the AvTech hangar at the Red Deer Regional Airport (formerly Hillman Air).

The aircraft and crews provided a 24-hr service, seven days a week throughout the period. Seven full-time pilots and four meteorologists were assigned to the project this year. Staffing all the pilot positionswas a major challenge this year due to the economic boom in Alberta and the high cost of living in


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Calgary. There was a shortage of qualified pilots at the start of the program. Roger Tilbury, Chief Pilotfrom the WMI Fargo head office spent the month of June training several new pilots. In addition, formerWMI cloud seeding pilots (Gavin Lange, Craig Lee, Rex Watson, Ben Hiebert, and Mark Friel),presently working in Alberta for other companies, were used when available on their days off or duringspecial leave to fly on the project. Their participation meant that we were able to train five new pilotsthis year that hopefully can be used on future projects. Overall, the personnel, aircraft, and radarperformed exceptionally well and there were no interruptions or missed opportunities in the service.High speed Internet was once again installed at the Calgary and Red Deer offices for the pilots so that

they could closely monitor the storm evolution and motion using the radar images on the web prior totake-off. This gave the pilots better knowledge of the storm situation to be encountered after they werelaunched.

Numerous public relations activities occurred this year, especially after the severe hail storms struck theCalgary area in mid-July. On July 5

th, T. Krauss was interviewed by the Olds Mountain View Gazette.The following TV crews visited the radar to film and conduct interviews: CTV Calgary on July 18th;Global TV Calgary on July 19th; City TV Red Deer-Edmonton on July 24th. T. Krauss was interviewedby 660 AM News radio in Calgary on July 26 th. WABC TV from New York sent a crew to the radar forfilm and interviews on Sept 13 as part of a documentary on cloud seeding.

All of the projects radar data, meteorological data, and reports have been recorded onto a portablehard drive as an archive for the Alberta Severe Weather Management Society. These data include thedaily reports, radar maps, aircraft flight tracks, as well as meteorological charts for each day. Thesedata can be made available for outside research purposes through a special request to the AlbertaSevere Weather Management Society.

A formal statistical evaluation of the hail suppression program is still not possible without receiving morecomprehensive, detailed high resolution property insurance claim data. Preliminary assessments fromunofficial reports within the insurance industry indicate that the program has been a financial success.The evidence has been consistently positive, however, the crop-damage data according to municipalitydoes not indicate a reduction in hail for the target area. Furthermore, there appears to be a trendtowards increasing hail within the target area over the past few years, and this is expected to continueinto the near future especially if La Nina conditions continue. The fact that the crop damage data doesnot show a reduction in crop damage within the target area is not surprising since not all hailstorms areseeded. Many hailstorms go unseeded if they do not threaten a town or city. Furthermore, small hailcan cause crop damage, even if it does not damage property. This also means that any reduction in

property insurance losses is not due to decreased storm activity due to climate change.

The project area has seen an exponential increase in population and property value. Therefore, the riskdue to hail has also increased exponentially. The same storm that caused $400 Million damage inCalgary in 1991 would likely cause >$1 Billion damage in 2007! This is consistent with hail damagesreported in the literature from the USA where several Billion dollar hail storms have occurred in the lastfew years e.g. 1998, 2001, 2003 as reported in http://lwf.ncdc.noaa.gov/oa/reports/billionz.html

The 2007 field operations ran very smoothly and, once again, there are no major recommendations forprogram improvements or upgrades. The following recommendations are presented for considerationby the ASWMS and WMI senior management next year.

It has been 12 years since the program started. Now there are many new people in the insurance

industry in Central Alberta who are not familiar with the history of the program and details of thecurrent cloud seeding project. It is recommended that an information seminar be organized toinform the insurance industry about the background, organization, and methodology of the cloudseeding project so that support for the program can continue based on current and accurateinformation.

2007 was a relatively quiet year in terms of the number of days with storms; however, large hail fellon an above average number of days. There were several days when the number of airplanes wasnot sufficient to seed all of the severe storms over cities and towns. Due to increases in thepopulation and risk within the project area, it is recommended that the ASWMS consider adding a

fourth airplane.
http://lwf.ncdc.noaa.gov/oa/reports/billionz.htmlhttp://lwf.ncdc.noaa.gov/oa/reports/billionz.html


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Finding qualified pilots this year was a problem, and this needs to be addressed prior to next year.Advertising and recruiting of pilots should be started earlier next spring. Application for ForeignWork Permits for US pilots should also begin early next spring since we now have ample

justification to demonstrate shortages of qualified staff in Alberta based on our experiences in 2007. There continues to be a need for more detailed property damage data. Several of the larger

insurance companies should be contacted in order to solicit, collect, and analyze the most recentand detailed property damage data so that a more detailed evaluation of trends in the loss-to-riskratios of property damage and the financial effectiveness of the program can be conducted.

T. W. KraussNovember 2007


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ACKNOWLEDGMENTS

WMI wishes to acknowledge the kind support of Todd Klapak (President) and Catherine Janssen (ChiefFinancial Officer) and the entire Board of Directors of the Alberta Severe Weather Management Society(ASWMS). The continued understanding, support, and cooperation of the ASWMS are greatlyappreciated.

A number of agencies and people deserve recognition and thanks. The cooperation of Mark McCrae,John Exley, and Rick Hubbs of the Air Traffic Control (ATC) Nav-Canada facilities at Calgary andEdmonton is gratefully acknowledged. The excellent cooperation by the ATC once again played a veryimportant role in allowing the project pilots to treat the threatening storms in an efficient and timelymanner as required, often directly over the city of Calgary.

Mr. Rob Cruickshank, Alberta Financial Services Corp. (AFSC) in Lacombe, is thanked for providing thecrop insurance information. Once again, special thanks also goes to Bob Jackson for sharing his officeand hangar at the Olds-Didsbury airport, used for the radar and communications control center. TimMorgan and Gavin Lange of Morgan Air are sincerely thanked for their cooperation and assistance inproviding the much needed but very scarce office and ramp space at the Calgary airport this season.The cooperation of all these people helped make the project a success and much more enjoyable.

WMI wishes to acknowledge the contributions of the staff who served the project during the summer of2007: meteorologists (Jason Goehring, Derek Blestrud, Dr. Viktor Makitov), electronics-radar technicianBarry Robinson, pilots in command (Roger Tilbury, Ian Callard, Dan Hollington, Pat Reilly, Rex Watson,Daniel Haines, Craig Lee, Joe Wiley, and Ben Heibert); the co-pilots (Joel Zimmer, Mark Friel, andJohnathon Seepaul), and the aircraft maintenance engineers (Gary Hillman and Dale Campbell). Thestaff performed exceptionally well as a team. The support of the WMI corporate head office in FargoND is acknowledged, specifically: Patrick and James Sweeney, Randy Jenson, Hans Ahlness, BruceBoe, Dennis Afseth, Cindy Dobbs, Mark Grove, Erin Fisher, and Mike Clancy are gratefullyacknowledged.


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Figure 1: Jim Sweeney (WMI Vice President) and Dr. Terry Krauss (WMI VP and ProjectManager).

Figure 2: Meteorologists Jason Goehring and Dr. Viktor Makitov.


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Figure 3: Meteorologist Derek Blestrud and Chief Pilot Roger Tilbury.

Figure 4: Gary Hillman (Aircraft Maintenance) and Barry Robinson (Electron ics Maintenance).


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Figure 5: Pilots Daniel Haines and Joel Zimmer.

Figure 6: Pilots Craig Lee and Mark Friel.


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Figure 7: Pilots Ian Callard and Dan Hollington.

Figure 8: Pilots Pat Reilly and Rex Watson.


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Figure 9: Pilots Joe Wiley and Johnathon Seepaul.


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TABLE OF CONTENTS

EXECUTIVE SUMMARY............................................................................................................................... 3

ACKNOWLEDGMENTS ............................................................................................................................... 6

TABLE OF CONTENTS.............................................................................................................................. 12

LIST OF FIGURES...................................................................................................................................... 14

LIST OF TABLES ....................................................................................................................................... 15

INTRODUCTION......................................................................................................................................... 16

THE 2007 FIELD PROGRAM..................................................................................................................... 17

PROJECT OBJECTIVES............................................................................................................................ 19

PRIORITIES................................................................................................................................................ 19

CONCEPTUAL HAIL MODEL.................................................................................................................... 21

HAIL SUPPRESSION HYPOTHESIS ............................................................................................................... 21PRECIPITATION EFFICIENCY ....................................................................................................................... 23

OPERATIONS PLAN .................................................................................................................................. 24

ONSET OF SEEDING................................................................................................................................... 24IDENTIFICATION OF HAIL PRODUCING STORMS ............................................................................................ 24CLOUD SEEDING METHODOLOGY ............................................................................................................... 25NIGHT TIME SEEDING ................................................................................................................................ 26STOPPING SEEDING ................................................................................................................................... 26SEEDING RATES ........................................................................................................................................ 26SEEDING MATERIALS ................................................................................................................................. 27FLARE EFFECTIVENESS TESTS ................................................................................................................... 29

Summary Of CSU Tests ..................................................................................................................... 30

PROGRAM ELEMENTS AND INFRASTRUCTURE.................................................................................. 31

GROUND SCHOOL .................................................................................................................................... 32

PUBLIC RELATIONS ................................................................................................................................. 32

FLIGHT OPERATIONS............................................................................................................................... 32

AIR-TRAFFIC CONTROL.............................................................................................................................. 32CLOUD SEEDINGAIRCRAFT........................................................................................................................ 34

Piper Cheyenne II.............................................................................................................................. 34Beech King-Air C90 .......................................................................................................................... 35C340A Aircraft ................................................................................................................................... 35

Meteorological Aircraft Instrumentation ............................. ............ Error! Bookmark not defined.

RADAR CONTROL AND COMMUNICATIONS CENTER......................................................................... 36

RADAR........................................................................................................................................................ 38

RADAR CALIBRATION CHECKS.................................................................................................................... 39

AIRCRAFT TRACKING GLOBAL POSITIONING SYSTEM (GPS).......................................................... 41

SUMMAR Y OF SEEDING OPERATIONS................................................................................................. 42

FLIGHTS.................................................................................................................................................... 42


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SEEDINGAMOUNTS ................................................................................................................................... 43COMPARISON OF 2007WITH PREVIOUS YEARS ........................................................................................... 45

STORM TRACK MAPS .............................................................................................................................. 47

WEATHER FORECASTING....................................................................................................................... 48

CONVECTIVE DAY CATEGORY (CDC) ......................................................................................................... 48COORDINATED UNIVERSAL TIME................................................................................................................. 49

DAILY BRIEFINGS....................................................................................................................................... 49METEOROLOGICAL STATISTICS................................................................................................................... 49FORECASTING PERFORMANCE ................................................................................................................... 52THE HAILCAST MODEL ............................................................................................................................... 54

JULY 15TH, 2007 CASE STUDY: A DAMAGING STORM IN CALGARY. ............................................. 55

METEOROLOGICAL SITUATION .................................................................................................................... 55RADAR SUMMARY...................................................................................................................................... 61SEEDING SUMMARY................................................................................................................................... 62

CLIMATE PERSPECTIVES........................................................................................................................ 63

ALBERTA CROP HAIL INSURANCE RESULTS...................................................................................... 66

CONCLUSIONS AND RECOMMENDATIONS.......................................................................................... 67

REFERENCES AND RECOMMENDED READING................................................................................... 69

APPENDICES ............................................................................................................................................. 73

A. ORGANIZATIONCHART............................................................................................................... 74B. DAILYWEATHERANDACTIVITIESSUMMARYTABLE2007..................................................... 75C. AIRCRAFTOPERATIONSFLIGHTSUMMARY2007................................................................. 108D. FLIGHTSUMMARYTABLE2007 ................................................................................................ 110E. FORMS......................................................................................................................................... 113F. SPECIFICATIONS FORPIPERCHEYENNEIIAIRCRAFT......................................................... 117G. SPECIFICATIONS FORBEECHCRAFTKINGAIRC90AIRCRAFT........................................... 118

H.

SPECIFICATIONSFOR

CESSNA

C-340

AIRCRAFT.................................................................. 119

I. GROUNDSCHOOLAGENDA ..................................................................................................... 120J. WMIAIRBORNEGENERATORSEEDINGSOLUTION .............................................................. 121K. DAILYMETEOROLOGICAL FORECASTSTATISTICS2007 ..................................................... 122L. PROJECTPERSONNELANDTELEPHONELIST...................................................................... 126


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LIST OF FIGURES

Figure 1: Jim Sweeney (WMI Vice President) and Dr. Terry Krauss (WMI VP and Project Manager). .................7

Figure 2: Meteorologists Jason Goehring and Dr. Viktor Makitov..........................................................................7

Figure 3: Meteorologist Derek Blestrud and Chief Pilot Roger Tilbury...................................................................8

Figure 4: Gary Hillman (Aircraft Maintenance) and Barry Robinson (Electronics Maintenance)..........................8

Figure 5: Pilots Daniel Haines and Joel Zimmer......................................................................................................9

Figure 6: Pilots Craig Lee and Mark Friel. ..............................................................................................................9

Figure 7: Pilots Ian Callard and Dan Hollington...................................................................................................10

Figure 8: Pilots Pat Reilly and Rex Watson............................................................................................................10Figure 9: Pilots Joe Wiley and Johnathon Seepaul.................................................................................................11

Figure 10: The average number of hail days per year, based on the 19511980 climate normals of Environment

Canada (1987) and taken from Etkin and Brun (1999)............................................................................................16

Figure 11: Map of southern Alberta showing the project target area (Figure courtesy J. Renick)........................19

Figure 12: The conceptual model of hailstone formation and hail mitigation processes for Alberta (adapted from

WMO, 1995). This schematic figure shows the cloud seeding methodology at cloud-top and cloud-base for a

mature hailstorm.......................................................................................................................................................22

Figure 13: A three-dimensional schematic figure of an Alberta hailstorm, showing the cloud seeding

methodology within the new growth zone.................................................................................................................23

Figure 14: Precipitation efficiency for High Plains convective storms. Known supercell hailstorms are labeled S.

Storms that produced rain only are labeled R (Browning, 1977). ...........................................................................24

Figure 15: A photo of a cloud seeding plane dropping ejectable flares during a cloud seeding penetration (photo

courtesy John Ulan)..................................................................................................................................................26Figure 16: Photograph of a burning BIP flare. ......................................................................................................27

Figure 17: Pilot Joel Zimmer attaching the ejectable flare racks on the belly of the King Air C90 seeding aircraft

designated as Hailstop 3...........................................................................................................................................28

Figure 18: Pilot Joel Zimmer attaching the burn-in-place (BIP) flares on the wing of the King Air C90 seeding

aircraft designated as Hailstop 3. ............................................................................................................................28

Figure 19: Yield of ice crystals (corrected) per gram of pyrotechnic versus cloud supercooling temperature

(T


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Figure 35: GEM model 12 hr forecast valid at 6 pm 15-July-2007 (00Z, 16 July 2007) of: Top Left = 500 mb

heights and vorticity; Top Right=1000-500 mb thickness; Bottom Left=700 mb heights and humidity; Bottom

Right= Precipitation.................................................................................................................................................56

Figure 36: GEM model 12 hr forecast valid at 6 pm 15-July-2007 (00Z, 16 July 2007) of: Top Left = 250 mb

heights and Jet Stream velocity; Top Right=high level wind; Bottom Left=tropopause heights; Bottom Right=

Low level wind. .........................................................................................................................................................57

Figure 37: ETA 12 hr forecast atmospheric sounding for Calgary at 6 pm (00UTC) on July 15th2007. Also shown

is the trace for a lifted parcel with Temperature 29C and Dew Point 19C as reported in Calgary at 4pm and 5pm .

..................................................................................................................................................................................57Figure 38: Map of surface 3-hr pressure changes and wind vectors at 5 pm (23Z) on July 15th, 2007. ...............58

Figure 39: Map of surface streamlines and equivalent potential temperature (Theta-E) at 5 pm (23Z) on July

15th, 2007.................................................................................................................................................................59

Figure 40: Surface moisture-flux divergence/convergence and wind gust map at 23Z (5 pm) on July 15th, 2007.

..................................................................................................................................................................................59

Figure 41: Water vapor satellite image at 5 pm (23Z 15 July 2007). ......................................................................60

Figure 42: Water vapor satellite image at 7 pm (01Z 16 July 2007). ......................................................................60

Figure 43: Maximum Reflectivity map for the storms on 15-July-2007. ..................................................................61

Figure 44: Aircraft tracks for Hailstop 1(green), 2(white), and 3(blue) on 15-July-2007......................................62

Figure 45: Time sequence of radar composite reflectivity displays and aircraft tracks over Calgary on July 15th,

2007. Hailstorms are identified with blue circles and their forecast tracks in 10 min intervals are shown with red

circles. The storm cells are annotated with their top heights in km. The aircraft seeding tracks are shown as

green and white lines................................................................................................................................................63Figure 46: Daily and accumulated rainfall for Calgary from Oct. 1, 2006 to Oct. 1, 2007. ...................................63

Figure 47: Daily and accumulated rainfall for Red Deer from Oct. 1, 2006 to Oct. 1, 2007..................................64

Figure 48: Departures from normal Precipitation during the summer of 2007 in Canada.....................................65

Figure 49: Departures from normal Temperature during the summer of 2007 in Canada. ....................................65

Figure 50: Alberta Agriculture Financial Services Corp hail insurance loss-to-risk statistics from 1981 to 2007

for the municipalities in the Target Area, Downwind, and North of the project area..............................................66

Figure 51: The frequency distribution of loss-to-risk ratio for the Target area before seeding (1981-1995) versus

the seeding period (1995 to 2007)............................................................................................................................67

LIST OF TABLES

Table 1: Canadian census figures (2006 versus 2001) for the largest towns and cities in the project area...........20Table 2: Yield results of ICE flares. .........................................................................................................................29

Table 3: Characteristic times for effective ice nuclei depletion and rate data. (LWC = 1.5 g m-3points are

average values).........................................................................................................................................................30

Table 4: Radar parameter calibration values for the ALBERTA-WMI WR100. ......................................................40

Table 5: Radar transmitted power calibration values measured during the 2007 season.......................................40

Table 6: Operational Statistics for 1996 to 2007. ....................................................................................................44

Table 7: Cloud seeding flare usage comparison by aircraft. ...................................................................................46

Table 8: Description of Convective Day Category (CDC) Index.............................................................................48

Table 9: Summary of daily atmospheric parameters used as inputs for the daily forecast the CDC during 2007. 50

Table 10: Summary of daily forecast atmospheric parameters on 34 hail days during 2007. ................................51

Table 11: Table of the Observed versus Forecast days with Hail and No-Hail for the summer of 2007................52

Table 12: Table of Forecast versus Observed CDC daily values 2007. ..................................................................53

Table 13: Annual Summary of Convective Day Categories (CDC) ........................................................................53Table 14: Table of Forecast versus Observed CDC daily values using HAILSCAST during the summer of 2007.54

Table 15: Probability of detection (POD). false alarm ratio (FAR) and critical success index (CSI) performance

of HAILCAST and WMI from 2002 to 2007. ............................................................................................................55


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INTRODUCTION

Hailstorms pose a serious threat to property and crops in the province of Alberta. Historically, claimsfor agricultural hail damage are received on an average of 50 days each year between 1 June and 10September (Summers and Wojtiw, 1971). The most recent climatology of hail in Canada waspublished by Etkin and Brun (1999) in the International Journal of Climatology. The average number ofhail days per year, based on the 19511980 climate normals (Environment Canada, 1987) is shown inFigure 10. The contours were hand drawn, based primarily upon about 350 weather stations. Thehighest frequency of hail in Canada occurs in Alberta between the North Saskatchewan River and theBow River, immediately downwind of the Rocky Mountain foothills. This region is often referred to ashail alley.

Figure 10: The average number of hail days per year, based on the 19511980 climate normalsof Envi ronment Canada (1987) and taken from Etkin and Brun (1999).

Etkin and Brun (1999) point out that the period 19771993 was associated with substantial increases inhail-observing stations. As the 19511980 hail climatology was mostly based on pre-1977 data, it had arelatively coarse resolution in comparison. An updated Alberta hail climatology for 19771993 hassince been completed. It has a greater resolution than the national climatology, and shows theimportance of some topographical features, such as the Rocky Mountains. The influence of localtopographical features on mesoscale hail frequency is a major control. After 1982, hail frequencies in

Alberta showed a significant increase. The City of Calgary is in a region that normally gets between 3and 4 hailstorms each year.


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By overlaying the hail frequency map with the population density map, the region of greatest financialrisk to insurance companies covers the area from Calgary to Red Deer and Rocky Mountain House.For this reason, this is the region that was selected as the target area for the hail suppression program.

Insurance claims due to hailstorms in urban areas worldwide have generally escalated over the past 10years. Denver Colorado was pounded by golf-ball to tennis-ball sized hail on July 11, 1990, anddamages reached a record (for the U.S.A. at that time) $625 million. In Canada, the damagesassociated with the severe hailstorm that struck Calgary on September 7, 1991 exceeded $416 million

(Insurance Bureau of Canada, 2004). Insured claims from the hailstorm that struck Sydney Australia onApril 14, 1999 were approximately $1.5 billion, making it the most damaging event in Australianinsurance history. A study by Herzog (2002) compiled and summarized the hailstorm damages in theUSA for the period 1994-2000 for the Institute for Business and Home Safety (IBHS). Verified haillosses amounted to $2.5 Billion per year, with the actual amount possibly being 50% higher. Personalbuilding losses totalled $11.5 Billion (66%), commercial building losses totalled $2.7B (15%), andvehicles accounted for $3.3B (19%). More recently, the most damaging hailstorm ever recorded in theUSA moved from eastern Kansas to southern Illinois on 10 April 2001, depositing 2.5 to 7.5 cm-diameter hailstones along a 585 km path, over portions of the St. Louis and Kansas City urban areascollectively created $1.9 billion in damage claims from a 2-day period, becoming the ninth most costlyweather catastrophe in the United States since property insurance records began in 1949 (Changnonand Burroughs, 2003).

Estimates of the average annual crop loss to hail have also continued to increase with time, from $50million annually in 1975 (Renick, 1975) to more than $150 million annually during the period 1980 -1985 (Alberta Research Council, 1986). Actual insured crop losses are typically in the $80M rangeannually (.

The new Alberta Hail Suppression Project was initiated in 1996 as a result of the increased frequency ofdamaging hailstorms in Alberta, compounded by an increasing population inside an area of high stormfrequency. It is the first project of its kind in the World to be entirely funded by private insurancecompanies with the sole objective of reducing the damage to property by hail. At this time, Alberta CropInsurance and the Provincial and Federal Governments do not contribute financially to the project,although they stand to benefit from the seeding.

Weather Modification Inc. (WMI) has been a leader in the field of hail suppression since the early1960's. With extensive knowledge and experience in the cloud seeding industry, WMI is best known forits successful hail suppression operations in the northern Great Plains and other cloud modificationservices around the world e.g. Argentina, Mexico, India, Indonesia, Mali and Saudi Arabia. WMI wasawarded the first contract to conduct the Alberta Hail Suppression Project in April 1996 by the AlbertaSevere Weather Management Society. The project was made an ongoing program of the Albertainsurance industry in 2001 because of the drop in hail damage costs in Alberta, counter to the trend inthe rest of the country and the World. The contract calls for the provision of all personnel and equipmentfor a turnkey system of cloud seeding and related services for the purpose of reducing hail damage toproperty in south-central (Calgary to Red Deer) Alberta. The organization chart of the project is shownin Appendix A.

THE 2007 FIELD PROGRAM

In 2007, WMI conducted the operational cloud-seeding program from June 1st to September 15th. Theproject is based upon the conceptual model, methodology, and research results of the long-term hailresearch project conducted by the Alberta Research Council from the late 1960s through 1985 (AlbertaResearch Council, 1986) and by WMI in North Dakota (Smith et al, 1997). The present program utilizesthe latest cloud seeding technology available, incorporating several notable improvements overprevious projects in the province. These improvements include:

New fast-acting, high-yield mixtures for the silver-iodide flares and acetone solution. The flares aremanufactured by Ice Crystal Engineering (ICE) of North Dakota. The new generation ICEpyrotechnics produce >10

11ice nuclei per gram of AgI at -4C, and produce between 10

13and 10

14

ice nuclei per gram of pyrotechnic between -6C and -10C. CSU isothermal cloud chamber tests


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indicate that at a temperature of -6.3C, 63% of the nuclei are active in


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Figure 11: Map of southern Alberta showing the project target area (Figure courtesy J. Renick).

PROJECT OBJECTIVES

The project has two main objectives:

Conduct cloud seeding using 3 aircraft with experienced crews to suppress hail for the purpose ofreducing damage to property;

Operate a C-band weather radar and collect weather information by skilled professionalmeteorologists for purposes of storm identification, accurate storm tracking, optimal direction ofaircraft to conduct cloud seeding for hail suppression purposes, and the collection of a data archivethat may be used for the scientific assessment of the program's effectiveness.

Priorities

Table 1 lists the recent census figures for the cities and towns within the project area. Priority is givenaccording to population, which is related to the risk of property damage. This list was posted in theradar control room as a constant reminder to the meteorologists of the priority when allocatingresources to storms on any given day. The biggest increases in population have occurred inCherstermere, Airdrie, Okotoks, Strathmore, Blackfalds, and Sylvan Lake. Project meteorologistsmade special note of the fact that the combined population of Turner Valley and Black Diamond is


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almost as large as Blackfalds or Didsbury. Storms that do not threaten a town or city are not likely to beseeded. Also, most storms are not seeded after they cross the QEII highway, except for storms east of

Airdrie and Calgary that might threaten Strathmore.

Table 1: Canadian census figures (2006 versus 2001) for the largest towns and cities in theproject area.

Priority Geographic namePopulation,

2006Population,

2001 % Change

Canada 31612897 30007094 5%

Alberta 3290350 2974807 11%

Calgary Metro Area 1079310 951494 13%

1 Calgary 988193 879003 12%

2 Red Deer 82772 67829 22%

3 Airdrie 28927 20407 42%

4 Okotoks 17145 11689 47%

5 Cochrane 13760 12041 14%

6 Lacombe 10742 9384 14%

7 High River 10716 9383 14%8 Strathmore 10225 7621 34%

9 Sylvan Lake 10208 7503 36%

10 Chestermere 9564 3856 148%

11 Innisfail 7316 6943 5%

12 Olds 7248 6607 10%

13 Rocky Mountain House 6874 6208 11%

14 Ponoka 6576 6355 3%

15 Blackfalds 4571 3116 47%

16 Didsbury 4275 3932 9%

17Turner Valley & BlackDiamond 3808 3474 10%

18 Three Hills 3089 2902 6%

19 Carstairs 2656 2254 18%

20 Crossfield 2648 2399 10%

21 Sundre 2518 2277 11%

22 Rimbey 2252 2154 5%

23 Penhold 1961 1729 13%

24 Vulcan 1940 1762 10%

25 Irricana 1243 1043 19%26 Bowden 1205 1174 3%

27 Bentley 1083 1040 4%

28 Trochu 1005 1033 -3%

29 Eckville 951 1019 -7%

30 Beiseker 804 838 -4%

31 Delburne 765 719 6%

32 Linden 660 636 4%


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33 Acme 656 648 1%

34 Caroline 515 556 -7%

35 Cremona 463 415 12%

CONCEPTUAL HAIL MODEL

The hail suppression conceptual model is based on the results of the former ARC research programand the experiences of WMI in the USA, Canada, Argentina, and Greece. It involves the use of silver-iodide reagents to seed the developing feeder clouds near the -10C level in the upshear, new growthpropagation region of hailstorms. The silver-iodide reagents initiate a condensation-freezing processand produce enhanced concentrations of ice crystals that compete for the available, super-cooled liquidwater in a storm and help prevent the growth of large damaging hail. The seeding also initiates theprecipitation process earlier in a cloud (cell) to speed up the growth of cloud hydrometeors via an ice-phase (graupel) to rain mechanism instead of continuing to grow to damaging hail.

Hail Suppression Hypothesis

The cloud seeding hypothesis is based on the cloud microphysical concept of "beneficial competition".Beneficial competition is based upon the documented deficiency of natural ice nuclei in the environment

and that the injection of silver iodide (AgI) will result in the production of a significant number of"artificial" ice nuclei. The natural and artificial ice crystals "compete" for the available super-cooled liquidcloud water within the storm. Hence, the hailstones that are formed within the seeded cloud volumeswill be smaller and produce less damage if they should survive the fall to the surface. If sufficient nucleiare introduced into the new growth region of the storm, then the hailstones will be small enough to meltcompletely before reaching the ground. Cloud seeding alters the microphysics of the treated clouds,assuming that the present precipitation process is inefficient due to a deficiency of natural ice nuclei.This deficiency of natural ice has been documented in the new growth zone of Alberta storms (Krauss,1981). Cloud seeding does not attempt to compete directly with the energy and dynamics of the storm.

Any alteration of the storm dynamics occurs as a consequence of the increased ice crystalconcentration and initiation of riming and precipitation sized ice particles earlier in the clouds lifetime.

The cloud seeding is based on the conceptual model of Alberta hailstorms which evolved from the

experiments and studies of Chisholm (1970), Chisholm and Renick (1972), Marwitz (1972a,b,c), Bargeand Bergwall (1976), Krauss and Marwitz (1984), and English (1986). Direct observational evidencefrom the instrumented aircraft penetrations of Colorado and Alberta storms in the 1970's and early1980s indicates that hail embryos grow within the time evolving "main" updraft of single cell storms andwithin the updrafts of developing "feeder clouds" or cumulus towers that flank mature "multi-cell" and"super-cell" storms (see e.g. Foote, 1984; Krauss and Marwitz, 1984). The computation of hail growthtrajectories within the context of measured storm wind fields provided a powerful new tool for integratingcertain parts of hail growth theories, and illustrated a striking complexity in the hail growth process.Some of this complexity is reviewed in the paper of Foote (1985) that classifies a broad spectrum ofstorm types according to both dynamical and microphysical processes thought to be critical to hailproduction. Hail embryo sources identified by Foote (1985) include the following: Embryos from first-ice in a time-developing updraft Embryos from first-ice in the core of a long-lived updraft

Embryos from flanking cumulus congestus Embryos from a merging mature cell Embryos from a mature cell positioned upwind Embryos from the edges of the main updraft Embryos created by melting and shedding Embryos from entrainment of stratiform cloud Embryos from embedded small-scale updrafts and downdrafts Recirculation of embryos that have made a first pass through the updraft core

The growth to large hail is hypothesized to occur primarily along the edges of the main storm updraftwhere the merging feeder clouds interact with the main storm updraft (WMO, 1995). The mature


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hailstorm may consist of complicated airflow patterns and particle trajectories, therefore, the cloud-seeding cannot hope to affect all embryo sources but attempts to modify the primary hail formationprocess. In other words; the cloud seeding cannot attempt to eliminate all of the hail but canreduce the size and amount o f hail.

Studies of the internal structure of large hailstones in Alberta and elsewhere have shown that hailstonescan have either a graupel hail embryo or a frozen drop hail embryo. The different hail embryos indicatedifferent growth histories and trajectories and illustrate the complexity within a single hailstorm. The

present seeding methodology attempts to compete with the graupel embryo process. Drop hailembryos are thought to originate from secondary sources (shedding from large existing hail stones, orvia a recirculation process at the edge of the main updraft). The seeding can only reduce the hail withdrop embryos if the liquid water can be reduced to limit their growth, or if the dynamics of the storm canbe affected to eliminate the recirculation processes that formed the drop embryo in the first place.

A schematic diagram of the conceptual storm model showing the hail origin and growth processeswithin a severe Alberta hailstorm is shown in Figure 12. A three-dimensional schematic figure of an

Alberta hailstorm is shown in Figure 13, showing the cloud seeding methodology in the new growthzone.

Figure 12: The conceptual model of hailstone formation and hail mitigation processes forAlber ta (adapted from WMO, 1995). This schemat ic figure shows the cloud seeding

methodology at feeder cloud tops and cloud-base for a mature hailstorm.


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Figure 13: A three-dimensional schematic figure of an Alberta hailstorm, showing the cloudseeding methodology within the new growth zone.

As mentioned previously, cloud seeding cannot prevent or completely eliminate the occurrence ofdamaging hail. We presently do not have the ability to predict with any certainty exactly the amount andsize of hail that would occur if cloud seeding did not take place. Therefore, we do not have the ability topredict with certainty the net effect of the seeding. Our purpose is to seed the new growth zone ofhailstorms and observe the amount and type of precipitation at the surface, as well as the radarreflectivity characteristics of the storm before, during, and after seeding. We expect that the successfulapplication of the technology will yield a decrease of damaging hail by approximately 50% of theamount that would have occurred if seeding had not taken place. This goal is consistent with the resultsreported in North Dakota (Smith et al, 1997) and in Greece (Rudolph et al, 1994). The decrease in hailcan only be measured as an average over time (e.g. 5 years) and over an area and then compared withthe historical values for the same areas. Because of these uncertainties, the evaluation of any hailmitigation program requires a statistical analysis. Both seeded storms and unseeded storms havevariability and populations of seeded and unseeded storms overlap in all measurements of theircharacteristics.

Precipitation Efficiency

A common question about cloud seeding concerns the effect on the rainfall. Krauss and Santos (2004)analyzed two years of Alberta radar data and concluded that seeded storms produced more rain thannon-seeded storms of the same height. The seeding effect was estimated to increase the mean rainfallvolume (averaged for categories 7.5 to 11.5 km height storms) by a factor of 2.2 with an average 95%confidence interval of 1.4 to 3.4. The seeded storms lived longer (+50%), had greater mean

precipitation rates (+29%), and had greater mean total rain area-time integrals (+54%).

There is a general (yet false) assumption by the public and some scientists that thunderstorms operateat near 100% efficiency in producing rainfall, therefore, any modification of the hail, or causing therainfall to start earlier, may limit the amount of precipitation that can fall later in a storms lifetime, downwind of the project area. There have been numerous studies of the fluxes of air and water vaporthrough convective clouds and these are summarized in Figure 14.

Precipitation efficiencies can vary widely from as little as 2% for storms studied by Marwitz (1972) andDennis et al. (1970) to near 100%. Marwitz (1972) and Foote and Fankhauser (1973) show that in thecase of High Plains storms there is an inverse relation between the precipitation efficiency and the


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environmental wind shear in the cloud-bearing layer. The least efficient storms tend to be supercellhailstorms; the highly efficient storms tend not to produce hail. The average wind shear on hail days in

Alberta is approximately 2.5 x 10-3 sec-1. This average shear value corresponds to an average

precipitation efficiency of approximately 50%.

It is logical that the production of large, damaging hail is a result of the natural inefficiency of the stormto produce rain. Therefore, the introduction of more precipitation embryos earlier in a clouds lifetime ishighly advantageous to the initiation of precipitation earlier, making the cloud more efficient as a rain

producer, and in the process reducing the amount and size of the hail. Increasing the rainfall from ahailstorm by 20% due to the seeding is a very achievable goal, and means that less water is lost eithervia the entrainment of dry environmental air through the sides and top of the cloud, or water lost to icecrystals that are exhausted out of the anvil at the top of the troposphere and which eventually sublimateback to the vapor phase at high altitudes.

Figure 14: Precipitation efficiency for High Plains convective storms. Known supercellhailstorms are labeled S. Storms that produced rain only are labeled R (Browning, 1977).

OPERATIONS PLAN

The following guidelines represent the current state of the science of hail suppression operations beingapplied by Weather Modification Inc.

Onset of Seeding

In order for cloud seeding to be successful, it is the goal of the program to seed (inject ice nucleatingagents) the developing "new growth" cloud towers of a potential hail producing storm at least 20minutes before the damaging hail falls over a town or city within the target zone. For the Albertaproject, the principle targets are the towns and cities within the project area. Since 20 min is theminimum time reasonably expected for the seeding material to nucleate, and have the seeded icecrystals grow to sufficient size to compete for the available super-cooled liquid water in order to yieldpositive results, a 30 min lead time is generally thought to be advisable.

Identification of Hail Producing Storms


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The height of the 45 dBZ contour was a criterion tested in the Swiss hail suppression program. TheSwiss research indicated that all hailstorms had 45 dBZ contours that exceeded the 5C temperaturelevel (Waldvogel, Federer, and Grimm, 1979). There was a False Alarm Rate (FAR) of 50%, largelybecause some strong rainstorms also met the criterion. However, it is preferable to make an error andassume that a heavy rainstorm is going to produce hail than to mistakenly believe that a hailstorm isonly going to produce heavy rain. Studies of Alberta hailstorms also indicated that 50% of all Albertahail storms had a maximum radar reflectivity greater than 45 dBZ, higher than the -5C level(Humphries, English, and Renick, 1987). The Russian criteria for hail identification stated that the height

of the 45 dBZ contour had to exceed the height of the 0C isotherm by more than 2 km (Abshaev,1999). Similarly, the criteria used by the National Hail Research Experiment in the USA 1972-1974 fora declared hail day was defined by radar maximum reflectivity greater than 45 dBZ above the -5C level(Foote and Knight, 1979).

Our experience suggests that the Swiss/Alberta/Russian/USA criterion is reasonable (Makitov, 1999).The physical reasoning behind it is simply that high radar reflectivity implies that significant supercooledliquid water exists at temperatures cold enough for large hail growth.

In Alberta, the TITAN cell identification program was set in 2007 to track any cell having >10 km3of 40dBZ reflectivity, extending above 3 km altitude (MSL). Each cell tracked by TITAN was then consideredto be a potential hail cell, therefore, this represents our seeding criteria. A storm is a seedingcandidate if the storm cell (as defined by TITAN) is moving towards, and is expected to reach, a town orcity within the target area in less than 30 min.

Cloud Seeding Methodology

Radar meteorologists are responsible for making the "seed" decision and directing the cloud seedingmissions, incorporating the visual observations of the pilots into their decisions. Patrol flights are oftenlaunched before clouds within the target area meet the radar reflectivity seeding criteria, especially overthe cities of Calgary and Red Deer. These patrol flights provide a quicker response to developing cells.In general, a patrol is launched in the event of visual reports of vigorous towering cumulus clouds orwhen radar cell tops exceed 25 kft height over the higher terrain along the western border on dayswhen the forecast calls for thunderstorms with large hail potential.

Launches of more than one aircraft are determined by the number of storms, the lead time required for

a seeder aircraft to reach the proper location and altitude, and projected overlap of coverage andon-station time for multiple aircraft missions. In general, only one aircraft can work safely at cloud topand one aircraft at cloud base for a single storm. The operation of three aircraft is used to provideuninterrupted seeding coverage at either cloud-base or cloud-top and/or to seed three stormssimultaneously if required.

Factors that determine cloud top or cloud base seeding are: storm structure, visibility, cloud baseheight, or time available for aircraft to reach seeding altitude. Cloud base seeding is conducted byflying at cloud base within the main inflow of single cell storms, or the inflow associated with the newgrowth zone (shelf cloud) located on the upshear side of multi-cell storms.

Cloud top seeding can be conducted between -5C and -15C. The 20 g pencil flares fall approximately1.5 km (approximately 10C) during their 35-40 s burn time. Figure 15 shows a cloud seeding plane

dropping flares. The seeding aircraft penetrate the up-shear edges of single convective cells meetingthe seed criteria. For multi-cell storms, or storms with feeder clouds, the seeding aircraft penetrate thetops of the developing cumulus towers on the upshear sides of convective cells, as they grow upthrough the -10C flight level.


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Figure 15: A photo of a cloud seeding plane dropping ejectable flares during a cloud seedingpenetration (photo courtesy John Ulan).

Night Time Seeding

Occasionally, with embedded cells or convective complexes at night, there are no clearly defined feederturrets visible to the flight crews or on radar. In these instances, a seeding aircraft will penetrate thestorm edge at an altitude between -5C and -10C, on the upshear side (region of tight radar reflectivitygradient) and seed by igniting an end-burner flare and injecting droppable pencil flares when updraftsare encountered. If visibility is good below cloud base, nighttime seeding at base is also performed.Lightning can often help provide illumination at the cloud base.

Stopping Seeding

Strictly speaking, if the radar reflectivity criteria are met, seeding of all cells is to be continued. However,seeding is effective only within cloud updrafts and in the presence of super-cooled cloud water, i.e. thedeveloping and mature stages in the evolution of the classic thunderstorm conceptual model. Thedissipating stages of a storm should be seeded only if the maximum reflectivity is particularly severeand there is evidence (visual cloud growth, or tight reflectivity gradients) indicating the possiblepresence of embedded updrafts. Storm cells being tracked by TITAN may not be seeded if there are noother indications of updraft or super-cooled liquid water, or if the storm does not threaten a town or city.

Seeding Rates

A seeding rate of one 20 g flare every 5 sec is typically used during cloud penetration. A higher rate isused (e.g. 1 flare every 2 to 3 sec) if updrafts are very strong (e.g. greater than 2000 ft/min) and thestorm is particularly intense. A cloud seeding pass is repeated immediately if there are visual signs ofnew cloud growth or if radar reflectivity gradients remain tight (indicative of persistent updrafts). If not, a5 to 10 min waiting period may be used between penetrations, to allow the seeding material to takeeffect and the storm to dissipate, or for visual signs of glaciation to appear or radar reflectivity values todecrease and gradients to weaken. This waiting period is meant to reduce the waste of seedingmaterial and help assure its optimum usage. Calculations show that the seeding rate of one flare every


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5 sec will produce >1300 ice crystals per litre averaged over the plume within 2.5 min. This is morethan sufficient to deplete the liquid water content produced by updrafts up to 10 m/s (2000 ft/min),thereby preventing the growth of hailstones within the seeded cloud volumes (Cooper and Marwitz,1980). For effective hail suppression, sufficient dispersion of the particles is required for the AgI plumefrom consecutive flares to overlap by the time the cloud particles reach hail size. The work by Grandiaet al. (1979) based on turbulence measurements within Alberta feeder clouds indicated that the time forthe diameter of the diffusing line of AgI to reach the integral length scale (200 m) in the inertial subrangesize scales of mixing, is 140 seconds. This is insufficient time for ice particles to grow to hail size,

therefore, dropping flares at 5 sec (assuming a true-airspeed of 80 m/s) intervals should providesufficient nuclei and allow adequate dispersion to effectively deplete the super-cooled liquid water andreduce the growth of hail particles. The use of the 20 gm flares and a frequent drop rate provides betterseeding coverage than using larger flares with greater time/distance spacing between flare drops. Infact, the above calculations are conservative when one considers that the center of the ice crystalplume will have a greater concentration of ice crystals.

For cloud base seeding, a seeding rate using two acetone generators or one end-burner flare istypically used, dependent on the updraft velocity at the cloud base. For an updraft >500 ft/min,generators and consecutive flares per seeding run are typically used. Cloud seeding runs are repeateduntil no further inflow is found. Acetone burners are used to provide continuous silver iodide seeding ifextensive regions of weak updraft are found at cloud base and in the shelf cloud region. Base seedingis not conducted if only downdrafts are encountered at cloud base, since this would waste seeding

material.

Seeding Materials

WMI exclusively uses silver-iodide formulation flares manufactured by Ice Crystal Engineering (ICE) ofDavenport, ND. The ejectable flares contain 20 gm of seeding material and burn for approximately 37sec and fall approximately 4000 ft. The end-burning or burn in place (BIP) flares contain 150 gm ofseeding material, and burn for approximately 6 min. A photograph of a burning BIP flare test is shownin Figure 16.

Figure 16: Photograph of a burning BIP flare.

Silver-iodide is dispensed using droppable/ejectable (shown in Figured 15 and 17) and/or end-burningpyrotechnics (Fig. 16) and/or acetone burners (shown in Figure 25). In 2007 the WMI acetonegenerators performed very well and the level of required maintenance decreased significantly. Crewskept a close watch on igniter rods, valves, nozzles, and seals in order that the generators operatedreliably. Details of the silver-iodide acetone solution are given in an Appendix. Arrangements were


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once again made with Solution Blend Services, a Calgary chemical company to pre-mix the acetoneseeding solution. All required handling, mixing, storage, and labelling requirements were satisfied.

Figure 17: Pilot Joel Zimmer attaching the ejectable flare racks on the belly o f the King Air C90seeding aircraft designated as Hailstop 3.

Figure 18: Pilot Joel Zimmer attaching the burn-in-place (BIP) flares on the wing of the King Ai rC90 seeding aircraft designated as Hailstop 3.


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Flare Effectiveness Tests

The Cloud Simulation and Aerosol Laboratory (cloud chamber) at Colorado State University has testedthe ice nucleating ability of aerosols produced from cloud seeding flares for many years (Garvey, 1975).Note: The CSU laboratory has now stopped this service and a new testing facility to conduct thesestandardized tests is desperately needed for the cloud seeding industry. The latest ICE pyrotechnicswere tested at CSU in 1999 and the results are reported in DeMott (1999). Aerosols were collected andtested at nominal temperatures of -4, -6 and -10C. At least two tests were done at each temperature,with greater emphasis placed on warmer temperatures. Liquid water content (LWC) was 1.5 g m -3 inmost tests, but was altered to 0.5 g m

-3in a few other experiments. In this way, information concerning

the rate-dependence on cloud droplet concentration was obtained. The primary product of thelaboratory characterization is the "effectiveness plot" for the ice nucleant which gives the number of icecrystals formed per gram of nucleant as a function of cloud temperature. Yield results for the ICE flaresat various sets of conditions are shown in Figure 19 and are tabulated in Table 2.

1.00E+10

1.00E+11

1.00E+12

1.00E+13

1.00E+14

1.00E+15

0 5 10 15

Supercooling (C)

Yield

(#

g-1p

yro)

ICE Pyro

July 1999

___________

___________

Figure 19: Yield of ice crystals (corrected) per gram of pyrotechnic versus cloud supercooling

temperature (T


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Tests were also performed using the method of DeMott et al., (1983) to determine the characteristictimes for effective ice nuclei depletion, and these are summarized in Figure 20 and Table 3.

y = 57.483x-1.9653

R2= 0.8298

y = 4.723x-1.1862

R2= 0.8552

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10 12Supercooling (C)

Time(minutes)

63

9

_________

_________

Figure 20: Times for 63% (diamond symbols) and 90% (square symbols) ice formation versus

supercooling (T


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3. Rates of ice crystal formation were very fast, suggestive of a rapid condensation freezingprocess. The balance of observations showed no significant difference in the rate dataobtained at varied cloud densities, supporting a conclusion that particles activate iceformation by condensation freezing.

The CSU isothermal cloud chamber tests indicate that, on a per gram basis of pyrotechnic, these valuesare comparable to the best product available worldwide in the pyrotechnic format. High yield and fast

acting agents are important for hail suppression since the time-window of opportunity for successfulintervention of the hail growth process is often less than 10 minutes. More information about the ICEflares can be found on the internet at www.iceflares.com.

PROGRAM ELEMENTS AND INFRASTRUCTURE

A schematic diagram of the operational elements for the hail suppression project is shown in Figure 21.Details of the individual elements are described in more detail in the following sections.

Figure 21: A schematic of the operational elements of the Alberta Hail Suppression Project.

The radiosonde (weather balloon) depicted in Figure 21 was part of the system on a limited basesduring 2003 and 2004, when WMI participated in the Alberta GPS Atmospheric Moisture Evaluation (A-GAME) research project with the University of Calgary. From those experiments we learned that the

ETA/NAM model from the USA does an excellent job in predicting the main features of the atmosphericprofile for Calgary and Red Deer. Although subtle details of inversion layers and moisture layers maynot be resolved, the meteorologists have generally sufficient information about the instability of theatmosphere to construct a good forecast. One of the greatest gaps in our knowledge and dataconcerns the presence, absence, or timing of trigger mechanisms for the onset of convection. Theincreasing availability of near real time surface and satellite images via the internet is improving thissituation. All meteorological information was received via the internet. WMI no longer needed acommercial agreement with Environment Canada.


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GROUND SCHOOL

A ground school was conducted prior to the commencement of the project field operations on May 30 th,2007 for all available project personnel. Ground School was held in the training room at ING Insurancein downtown Calgary. Operational procedures about who does what, where, when and why, as well asgeneral conduct and reporting requirements were presented and reviewed at the ground school. Tworepresentatives of NAV Canada in Calgary and Edmonton participated in the ground school. A copy ofthe Ground School Program, as well as copies of the Flight Log and Radar Log forms, are included inthe Appendices. The ground school training topics included:i. program overview and design, project area, target areas, and prioritiesii. overview of operations and proceduresiii. cloud seeding hypotheses for hail suppressioniv. cloud seeding theory and techniquesv. aviation weather problems and special proceduresvi. aircraft controlling techniques and proceduresvii. seeding aircraft equipment and characteristicsviii. weather radar equipment and basic principlesix. basic meteorological concepts and severe weather forecastingx. weather phenomena, fronts, and stormsxi. daily routines and proceduresxii. communications procedures

xiii. computers, documentation, and reporting proceduresxiv. safety, security precautions and procedures

PUBLIC RELATIONS

Numerous public relations activities occurred this year, especially after the severe hail storms struck theCalgary area in mid-July. On July 5th, T. Krauss was interviewed by the Olds Mountain View Gazette.The following TV crews visited the radar to film and conduct interviews: CTV Calgary on July 18th;Global TV Calgary on July 19th; City TV Red Deer-Edmonton on July 24th. T. Krauss was interviewedby 660 AM News radio in Calgary on July 26 th. WABC TV from New York sent a crew to the radar forvideo and interviews on Sept 13 as part of a documentary on cloud seeding.

FLIGHT OPERATIONS

Three specially equipped cloud seeding aircraft were dedicated to the project. The aircraft and crewsprovided 24 hr coverage, seven days a week throughout the period. Two aircraft were stationed inCalgary and one aircraft in Red Deer. This permitted close proximity to storms and fast response tolaunch decisions. Delays in launching from Calgary were minimized thanks to the co-operation of Nav-Canada air traffic control in Calgary.

When convective clouds were detected by radar, the seeding aircraft were placed on standby status.Aircraft on standby status are able to launch and reach a target cloud within 60 min after the request tolaunch has been made by the controlling meteorologist. When seedable clouds are imminent, theseeding aircraft are placed on alert status. Aircraft on alert status are able to launch and reach a targetcloud within 25 min after the request to launch. Aircraft were available and prepared to commence a

seeding mission at any time and the seeding of a storm often continued after darkness with due regardto safety.

Ai r-Traff ic Control

Prior to the start of field operations, arrangements were made with NAV Canada managers of Air TrafficServices in Calgary and Edmonton to coordinate the cloud seeding aircraft operations. Permission wasgranted to file pre-defined flight plans for the project aircraft, with special designations and fixedtransponder codes. The designated aircraft were as follows: Hail-Stop 1 for the Cheyenne II airplane(N234K) based in Calgary, Hail-Stop 2 for the C340 aircraft (N457DM) based in Calgary, and Hail-Stop3 for the King Air C90 aircraft (N911FG) stationed in Red Deer.


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Direct-line telephone numbers were used to notify air traffic controllers of cloud seeding launches.Aircraft were launched to a specific location identified by VOR and DME coordinates, or town. Distinctair traffic clearance was given to project aircraft within a 10 nautical mile radius of the specified stormlocation. Cloud top aircraft were given 2,000 ft clearances above their altitude and 7,000 ft below theiraltitude. Cloud base aircraft were given a +/- 1,000 ft altitude clearance. This procedure worked verywell in general. On a few occasions, seeding aircraft were asked to climb to a higher altitude over thecity of Calgary or to suspend seeding for a few minutes (


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Cloud Seeding Aircraft

Piper Cheyenne II

The Cheyenne II is a high performance twin-engine turboprop aircraft that has proven itself duringseeding operations. The Cheyenne II stationed in Calgary, Hail Stop 1 (N234K), is shown in Figure 23.

In Alberta, two pilots are used at all times for improved communications and safety. Standardequipment includes full dual VFR/IFR instrumentation, pressurized cabin, and emergency oxygen. TheCheyenne II has full de-ice equipment and is particularly well suited for flying in icing conditions forextended periods of time. These conditions are common at seeding altitudes within the thunderstormsof Alberta. The longer mission times of this aircraft can provide coverage of the entire project area ifrequired, allowing significant savings in aircraft, fuel and personnel costs. The added performance ofthe Cheyenne II means that it has sufficient power to climb safely above the dangerous icing zone(-10C to -15C) if required, or descend to lower and warmer altitudes to de-ice and quickly climb backup to feeder cloud-top seeding altitude. It can also provide accurate measurements of cloud conditionsand cloud temperature. A third seat was provided for training or observing purposes. The majoradvantages of the Cheyenne II are as follows: 4 hour duration or more for longer seeding missions and better seeding coverage; lower Jet fuel price per liter; reserve power for severe icing conditions;

high speed for rapid response or ferry between target areas; and higher margin of safety;

The specifications of the Cheyenne II are given in an Appendix. All three aircraft were equipped withflare racks carrying 306 droppable flares containing 20 grams of AgI and also 28 end-burning flarescontaining 150 grams of AgI for seeding at cloud base. The Cheyenne II was also equipped with GPSnavigation system, onboard weather avoidance radar, and a VHF radio system for direct contact withoperational personnel at the communications and control center.

Figure 23: Piper Cheyenne II aircraft (N234K) designated as Hail-Stop 1 shown at the CalgaryAirpor t.


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Beech King-Air C90

Figure 24: Beech Craft King-Air C90 aircraft (N911FG) designated as Hail-Stop 3 shown at theOlds-Didsbury Airport.

A photo of the Beechcraft King Air C90 designated Hail Stop 3 (N911FG) is shown in Figure 24 at theOlds-Didsbury Airport. The specifications of the King Air C90 are given in an Appendix. The King Airwas similarly equipped as the Cheyenne II. The Cheyenne II and King Air C90 are both highperformance twin-engine turboprop aircraft that have proven themselves during seeding operations.

C340A Aircraft

Cloud seeding was also conducted using one Cessna 340A aircraft equipped with ejectable flare bellyracks, wing mounted flare racks, and acetone burners. The aircraft registered as N457DM wasdesignated as Hail-Stop 2 (shown in Figure 25). The C340A aircraft is a pressurized, twin-engine, sixcylinder, turbocharged and fuel-injected all weather aircraft. The C340 aircraft also has a weatheravoidance radar and GPS navigation system. Complete specifications for the C340 are given in an

Appendix. The C340 aircraft carried 306 20-g pencil flares and 24 150-g end-burning flares and two 7US gallon acetone burners. Although the C340 can seed at cloud top, its performance is rather limitedin known icing conditions. Therefore, the C340 is used primarily as a cloud-base seeder.


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Figure 25: C340A aircraft (N457DM) designated as Hail-Stop 2 and configured to seed withdroppable flares, end-burning flares, and AgI acetone burners.

RADAR CONTROL AND COMMUNICATIONS CENTER

The projects radar control room consists of the Airlink computer with radio telemetry modem for GPS

tracking information, as well as the TITAN computer and display, and the meteorological dataacquisition (Compaq) computer. Controllers communicated with the seeding aircraft using a VHF radioat 122.95 MHz frequency. The controlling duties were shared by Terry Krauss, Jason Goehring, DerekBlestrud, and Viktor Makitov (shown in Figure 26).

An upgraded TITAN radar display and analysis computer system was installed in 2004 (shown in Figure27). The new TITAN was able to display several new hail parameters that gave the meteorologistsadditional information to improve identification of hailstorms and improved the direction of the aircraft tothe most important hail growth regions of the storm. The TITAN radar images were sent to the WMIweb server at 5-min intervals, although there were often missing images in the web archive which wereblamed on computer problems and interruptions in the microwave internet connection at the radar. Amore reliable radar file transfer routine will be investigated for the future. High speed Internet wasinstalled for the pilots in Calgary and Red Deer so that the pilots could closely monitor the stormevolution and motion. This gave the pilots better knowledge of the storm situation they were going toencounter when they were launched.


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Figure 26: Dr. Viktor Makitov in the communications control room, showing the CIDD andTITAN, disp lays.

Figure 27: TITAN dual-display showing the various radar pictures and satellite photo availableto the radar controller on 29-July-2006.

A new Configurable Interactive Data Display (CIDD) computer system was installed in 2004. The newCIDD system was routinely set to display an animated 1-hour movie loop of the higher resolution polarradar data, super-imposed on a terrain map background. An example of the WMI-NCAR CIDD(Configurable Interactive Data Display) system used this year is shown in Figure 28.


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Figure 28: WMI-NCAR CIDD display showing radar reflectivi ty data and topography. A verticalcross-section and clear-air outfl ow boundary are also shown.

RADAR

The WMI C-band weather radar is located at the Olds-Didsbury Airport Hangar #4 (Jackson hangar).The radar coordinates are 51.71 N Latitude, 114.11 W Longitude, with a station elevation of 1024 mabove sea level. The WMO station identifier is #71359 and the ICAO airport identifier is CEA3. Anupgraded C-band weather radar was installed in 2003. The new radar was very reliable and is moresensitive than the previous, older unit, and was able to detect clouds earlier in their development cycle.The radar performed very well and there were no major interruptions in service.

The radar is an Enterprise Electronics Corporation WR-100, C-band radar with an 8-ft antenna. Apicture of the radar is shown in Figure 29. The WMI C-band (5 cm wavelength) radar is tower mountedand enclosed in a radome to provide safe, all weather operation. The nominal specifications of theC-band radar are: peak power = 250 kw, minimum detectable signal = -107 dBm, circular beam width =1.65 deg. The minimum detectable signal corresponds to approximately 10 dBZ at 100 km range. Acomplete list of specifications for the C-band radar is given in the following section. An uninterruptablepower supply (UPS) is used to assure there were no losses of service in the event of a power surge ordrop. A gas-powered generator was used to provide emergency back-up power in the case of a powerfailure. Line power was very reliable at the airport during the summer and there were only a fewmomentary lapses in line-power during particularly bad lightning storms. The UPS and emergencygenerator worked very well. On September 16th the radar was shut off for the season; however, thetower and radar transmitter and display equipment have remained in place until next year.

The radar antenna was raised 8 ft in 2001 in order to provide more clearance above nearby buildingsthat had been constructed at the Olds-Didsbury Airport. The base elevation radar scan was set to 0.8degrees elevation in order reduce the amount of ground clutter, yet still provide a good viewing angle ofthe low-level precipitation at far ranges, especially over Calgary and Red Deer. The radar transmitter islocated inside a garden shed built directly under the radar tower (shown in Figure 29). The radar shedis insulated and air-conditioned. The radome was last repainted on August 25

th, 2006.


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Figure 29: WMI C-band radar at the Olds-Didsbury airport.

The radar data acquisition computer RDAS is programmed to control the radar antenna such that acomplete volume scan of 18 elevation steps, up to 45elevation, was performed about every 4.8 min.

The RDAS computer sends the polar coordinate radar data to the TITAN computer via a local areanetwork and the TITAN computer performs the Cartesian transformation and records a permanentarchive of all of the scans. The polar data were stored and displayed on the CIDD computer. All of theTITAN volume-scan radar data collected during 2007 have been recorded on CD-ROM. The GIF PPIpicture files created every 5 min, have been archived onto CD-ROM.

Radar Calibration Checks

The quantitative use of radar requires that various parameters of the system be measured andcalibrated. The WMI WR100 C-band radar located at the Olds-Didsbury Airport is used to direct seedingaircraft in the Alberta Hail Suppression Project. As such, it needs to provide accurate values of radarreflectivity along with range, azimuth and elevation.

Assuming that all the terms relating to the electrical components and propagation of the radar beam areconstants and if we always assume we are looking at water, a simplified radar equation takes the form(Rinehart, 1997):

z = C prr2

Thus, calculating radar reflectivity factor z is

Wmi Alhap Final Report 2007

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Transcript of Wmi Alhap Final Report 2007