Research Article Observation and Numerical Simulation of ...

Research ArticleObservation and Numerical Simulation of Terrain-InducedWindshear at the Hong Kong International Airport ina Planetary Boundary Layer without Temperature Inversions

P W Chan and K K Hon

Hong Kong Observatory Hong Kong

Correspondence should be addressed to P W Chan pwchanhkogovhk

Received 25 September 2015 Revised 5 January 2016 Accepted 12 January 2016

Academic Editor Anthony R Lupo

Copyright copy 2016 P W Chan and K K Hon This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Terrain-induced windshear at Hong Kong International Airport (HKIA) could be hazardous to the landing and departing aircraftSuch windshear occurring in a planetary boundary layer without temperature inversions is studied in this paper by using the datafrom the Terminal Doppler Weather Radar and Light Detection and Ranging systems A high resolution numerical model calledaviation model (AVM) is also employed to find out its capability to forecast the occurrence of such windshear The model is foundto have skills in capturing the terrain-induced windshear including the terrain-inducedmicroburst due to themountains of LantauIsland Moreover the windshear detection algorithm as applied to the AVM output called AVM-GLYGA is able to give advancealert for the occurrence of low-level windshearThemodel also offers newdataset such as vertical velocity and vertical cross sectionsacross thewindshear feature to study the terrain-inducedwindshear phenomenawith new insightsTheAVM is found to have goodskills in depicting the terrain-disrupted airflow at the airport area andmore comprehensive study would be conducted to study theskills of AVM-GLYGA as compared with pilot windshear report as sky truth

1 Introduction

The Hong Kong International Airport (HKIA) is situatedin an area of complex terrain To the south of the airportthere is the mountainous Lantau Island with peaks risingto about 1 km above mean sea level (amsl) with valleysas low as 400m amsl in between When winds blow fromeast through southeast to southwest there could be terrain-induced airflow disturbances that may affect the operation ofthe aircraft at HKIA They may take the form of significantlow-level windshear which means a headwindtailwind (iewind component along the runway orientation) change of 15knots or more below 1600 feet along the glide paths abovethe aerodrome or significant low-level turbulence which isquantified in terms of the cube root of eddy dissipation rate(EDR) following international practice Moderate turbulencemeans an EDR between 03 and 05m23sminus1 and severeturbulence refers to EDR above 05m23sminus1 Windshear hasbeen reported to occur in aircraft incidentsaccidents in the

other airports such as Keller et al [1] In Hong Kong low-level windshearturbulence mostly occurs in the spring timewhen there is stable atmospheric boundary layer and insummer time when there is thunderstorm or strong south-westerly winds (eg strong southwest monsoon or underthe influence of tropical cyclones) Statistically a significantwindshear report is received for every 500 flights thoughthere may be cases with significant windshear encounteredbut without reporting to the air traffic control About 70of the reports are due to terrain-disrupted airflow whenwind is blowing from east through southeast to southwestAbout 20 of the reports are due to sea breeze (with possiblywind direction shear) The remaining reports are due tothunderstorms low-level jets and so forth

Apart from terrain-disrupted airflow thunderstorms atthe airport can also bring about significant windshear to theairport The most severe form of windshear is microburstwhich means low-level headwind loss of 30 knots ormore for example in precipitation as detected by a radar

Hindawi Publishing CorporationAdvances in MeteorologyVolume 2016 Article ID 1454513 9 pageshttpdxdoiorg10115520161454513

2 Advances in Meteorology

However besides thunderstorms terrain-disrupted airflowcan also bring about microburst called the terrain-inducedmicroburst if the headwind loss is found to reach 30 knotsor more and in rain for example in tropical cyclone orsouthwest monsoon situation One case of terrain-inducedmicroburst has been documented in Shun and Lau [2] whichdiscusses terrain-induced microburst in neutral atmosphericcondition as associated with the strong winds of a tropicalcyclone In the present paper this kind of microburst insouthwest monsoon is considered but in terms of prevailingwind flow atmospheric boundary layer structure and theorientationlocation of terrain-induced microburst the twocases are rather similar

In order to monitor low-level windshear and turbulenceat HKIA the Hong Kong Observatory (HKO) operates asuite of meteorological equipment at the airport area ATerminal DopplerWeather Radar (TDWR) has been runningto the northeast of the airport to monitor the change ofradial velocity in rain Since the radar beam is orientedalong the runway the radial velocity change may be takenas a headwindtailwind change It is a C band area withsignificant sidelobe depression so that it could be used tomeasure rain drop return signals close to the sea and landsurfaces In nonrainy weather conditions the Doppler LightDetection and Ranging (LIDAR) systems could be used forwindshear and turbulence detection There are two LIDARsystems running at HKIA each serving a particular runwayof the airport A laser beam with a wavelength of about 2microns is used and dust and aerosols in the air are tracked inorder to measure the wind The TDWR and LIDAR systemsare used for real-time detection of low-level windshear andturbulence Their technical details and applications couldbe found in Shun and Johnson [3] and Shun and Chan[4] respectively Observations of terrain-disrupted airflow inother areas of complex terrain could be found in the literaturefor example Mobbs et al [5]

Apart from detection-based service the Observatoryalso attempts to forecast the changes in low-level wind Inparticular an aviation model (AVM) based on WeatherForecast and Research (WRF) model [6] has been runningfor the airport area with a spatial resolution down to 200mThe output wind data are ingested into the LIDAR windshearalerting algorithm also called the glide-path scan windshearalerting algorithm (GLYGA) to forecast the occurrence oflow-level windshearThe low-level turbulence is predicted bydirectly outputting the forecast EDR based on the large eddysimulation (LES) boundary layer parameterization schemeThe model has been found to be successful in predictingterrain-disrupted airflow in stable boundary layer includingFoehn wind and mountain wave The configuration of AVMand its application for stable boundary layer flow could befound in Chan andHon [7] An account of the earlier versionof the model is given in Wong et al [8] Lee waves in otherareas of complex terrain and the forecast of such waves couldbe found in Vosper et al [9] Terrain-induced windshearhas been studied for other airports using high resolutionnumerical model for example in Boilley and Mahfouf [10]Orographic effects (ie valley breezes and hill effects) aresimulated very well in the high resolution model and could

lead to a better prediction of vertical windshear or localturbulence

In this paper a number of new applications of AVMare described It is used for a case without temperatureinversions in the boundary layer basically in the summer timeof southern China to see its performance in predicting theterrain-disrupted airflow and thus low-level windshear andturbulence that would be crucial to the operating aircraftat HKIA Also this is the first time that terrain-inducedmicroburst is forecast and the structure of this kind ofmicroburst is studied in slightly greater depth by looking atthe vertical cross section of the model simulated wind fieldIt is hoped that the paper would be a useful reference forother airports in which terrain-disrupted airflow would beone crucial factor in their operations particularly about thedetection and forecasting of the windshear and turbulenceunder similar atmospheric conditions It is noted that thispaper only discusses one kind of low-level windshear associ-ated with terrain-disrupted airflow namely boundary layerwithout temperature inversion in the summer time whichis rather typical Windshear can also occur in Hong KongInternationalAirport (and in fact farmore frequent) in springtime in the presence of temperature inversions inside theatmospheric boundary layer

The boundary layer in Hong Kong mostly has a height ofabout 1 to 2 km above ground It may be determined from theoccurrence of temperature inversion in the radiosonde datafor example trade wind inversion In the spring time therecan be temperature inversion associated with the cooler con-tinental airmass near the surface undercutting the warmermaritime airmass aloftThe heights of such inversions can bein the order of 1 km above sealand surface In the previouspapers (eg Chan and Hon [7]) terrain-disrupted airflowoccurs with the appearance of temperature inversion withinthe boundary layer This paper will discuss terrain-disruptedairflow without the presence of temperature inversion insidethe atmospheric boundary layer This kind of situation mayoccur in summer time and can be rather typical under theinfluence of strong southwest monsoon

2 Background Meteorological Condition

The surface isobaric chart at 00 UTC of the day namely21 July 2015 is shown in Figure 1 There is surface troughof low pressure over inland areas of southern China Alongthe coast the strong southwest monsoon is prevailing whichcould favour the occurrence of terrain-disrupted airflow atHKIA

The upper air meteorological condition may be revealedby the upper air ascent (radiosonde) launched at Kingrsquos Parkwhich is located at about 20 km to the east of the airportat 00UTC of the day The vertical profiles of the weatherelements can be found in Figure 2 It could be seen that thewinds below 2000m amsl are basically southwesterly Thewind speed profile suggests that between 600m and 1700mamsl there is a band with wind speed greater than 20ms Asa result strong southwesterly winds prevailed in the southernChina regionThe temperature and humidity profiles are alsogiven in Figure 2 together with the potential temperature

Advances in Meteorology 3

Hong Kong

Figure 1 The surface isobaric chart at 00 UTC 21 January 2015

profile with the calculated Brunt-Vaisala frequency (119873) andcross-mountain wind speed (119880) The atmosphere is basicallysaturated within the boundary layer No temperature inver-sion could be identified

3 Terrain-Induced Microburst Case

The TDWR sounds out microburst alert (MBA) in the earlymorning of 21 July 2015 A sample radial velocity plot from theTDWR at that time could be found in Figure 3(a) It couldbe seen that the background flow is strong southwesterlywith the winds blowing towards the radar Downstream ofthe Lantau terrain there are a number of streaks (narrowelongated areas) of higher wind speeds and lower windspeeds which are highlighted in Figure 3(a) At a streak ofhigher wind speed downstream of Siu Ho Wan (location inFigure 3(a)) it is connected with an area of lower wind speedjust emerging from the terrain The existence of an area ofhigher southwesterly wind and another area withmuch lowerwind speed in proximity results in amicroburst alert becausethe radial velocity change reaches 30 knots or more in rain

To study the wind streaks in greater detail vertical crosssections aremade in Figure 3(a) Firstly it could be seen fromFigure 3(a) that the higher wind streaks are associated withlower land over Lantau Island (ie 11015840 31015840 51015840 and 71015840 associatedwith 1 3 5 and 7) and lower wind streams are associatedwith higher land over Lantau Island (ie 21015840 41015840 and 61015840 areassociated with 2 4 and 6) The vertical cross section ABis shown in Figure 3(b) At the higher surface wind speedthe jet core is lower as shown in 1 3 and 5 On the otherhand for lower surface wind speed the jet core is higher

as shown in 2 and 4 due to obstruction of the terrain Thispoint is confirmed by the vertical cross sections in Figures3(c) and 3(d) In Figure 3(c) the jet core is about 700 to 800mabove sea surface In Figure 3(d) the jet core is about 300 to400m above sea surface The southwesterly wind streaks inthis case are mainly due to effect of the terrain on the strongbackground southwest monsoon

The Graphical Situation Display (GSD) of the Observa-toryrsquos Windshear and Turbulence Warning System whichsummarizes the windshear and turbulence alerts in force inreal time is shown in Figure 4 The MBA area is orientednorth-northeast to south-southwest just downstream of SiuHo Wan and alerts (headwind loss of 40 knots) are in forcefor the runway corridors to the east of the southern runwayof HKIAThisMBA is similar to the one documented in Shunand Lau [2]

The forecast surface wind from AVM is examined at thattime to see if there is any signature of terrain-induced MBAin the model simulation The 7-hour forecast of surface windbased on the model run at 14 UTC 20 July 2015 is shownin Figure 5 It could be seen that the winds are rather lightover the valley just upstream of Siu HoWan The winds thenturn to southwesterly after leaving this valley and there isstrong southwesterly generally prevailing over the runwaycorridors (within the square boxes which are alert areas forwindshearturbulence) This distribution of wind speed isgenerally consistent with that given by the TDWR and itresults in the occurrence of an area of ldquoterrain-inducedMBArdquoin the model simulation Similar change of the wind speedand wind direction could be found in other valleys and theadjacent runway areas such as the region aroundTungChung


Hei

ght (

m am

sl)200019001800170016001500140013001200110010009008007006005004003002001000

Direction (deg)0 30 60 90 120 150 180 210 240 270 300 330 360

(a)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000

Speed (ms)0 5 10 15 20 25 30

(b)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000

Temperature (∘C)minus5 0 5 10 15 20 25 30 35

TemperatureDew point

(c)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000569 57 571 572 573 574 575

N = 0016 U = 270

N = 0009U = 377

N = 0012U = 532

N = 0008U = 328

ln 120579

(d)

Figure 2 The radiosonde ascent data at Kingrsquos Park at 00 UTC 21 July 2015 (a) wind direction (b) wind speed (c) temperature (blue) anddew point (pink) and (d) potential temperature

(location in Figure 5) though the radial velocity change issmaller and thus MBA has not been triggered by the TDWR

The simulation of the existence of the terrain-inducedMBA by AVM allows the possibility of studying the windstructure of theMBA in greater detail A vertical cross sectionis made as in Figure 5 and it is shown in Figure 6 It isnot in the orientation of the measurement radials of theTDWR but is taken to be along themaximum change of windspeed from the valley at Siu Ho Wan to the sea and highersurface wind speed area to the north Figure 6(a) showsthe north-south component of the wind and Figure 6(b)shows the wind speed distribution It could be seen that thetwo distributions are very similar and thus the north-southcomponent of the wind makes a significant contribution tothe wind speed distribution In general the wind speeds arehigher over the mountain top as expected with the jet coreat a height of about 400 to 500m above the local terrainHowever downstreamof themountains over the airport areathere is a similar high speed region over the sea surface

This appears to be related to the downward transport ofthe horizontal momentum in the downslope wind In factsignificant downward motion is simulated down the hill inthe vertical velocity plot at Figure 6(c) This core of higherwind speed together with the generally lighter winds insidethe valley contributes to the occurrence of terrain-inducedMBA It is interesting to note from Figure 6(c) that thereappears to be a wave also between 1200 and 2000m above thearea of higher wind speed over the airport area The physicalsignificance of this wave is yet to be studied

4 Fluctuating Headwind andLow-Level Turbulence

Apart from terrain-induced MBA there are also fluctuationsin the headwind profile along the runway and its extendedcenterline so that the aircraft may experience low-levelwindshear Such a case occurs at about 0320 UTC 21 July2015 There was an aircraft landing at the north runway from


Siu Ho Wan1

23

45

6 7

A

B

1998400

3998400

2998400

4998400

5998400

6998400 7

998400

(Kno

t)

50454035302520175151251000800600400200000minus000minus200minus400minus600minus800minus1000minus125minus15minus175minus20minus25minus30minus35minus40minus45ltminus45UnderNo data

(a)

A B1 2 3 4 5

(b)

4 4998400

(c)

1 1998400

(d)

Figure 3The TDWR radial velocity plot at 06-degree conical scan at the time of terrain-induced microburst that is 053624 am of 21 July2015 Higher wind speed streaks are indicated by solid red arrows and lower wind speed streaks are indicated by dashed red arrowsThe timedisplayed is in Hong Kong time (UTC + 8 hours) The vertical cross sections AB 4-41015840 and 1-11015840 are shown in (b) (c) and (d) respectively

Figure 4 The GSD display at the time of terrain-induced microburst which is given as a red ellipse The arrows are the windshear alertsprovided by LIDAR and the brown dotted area is the turbulence alerting area The background yellowgreen is the TDWR radar reflectivityas expressed as the intensity level of precipitationThe time displayed is in UTCThe minus40 knots microburst area (solid red ellipse) just touchesupon the 3-nautical-mile ARENA box (white) to the east of the south runway


Tung Chung

Siu Ho Wan

HKO AVM-HKASurface zoom Mon2015-07-20 2100 UTC

Initialized at UTC2015-07-20 1400

22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

10 15 20 25 30 35 40 45 50 55 60 65 70

Forecast 3km reectivity (dBZ)

Figure 5The forecast surface wind byAVMat 21 UTC 20 July 2015for the model run initialized at 14 UTC 20 July 2015 The boxes onthe two sides of each runway are the locations at 1 2 and 3 nauticalmiles away from the runway end The location of the vertical crosssection of Figure 6 is shown as a dotted line Height contours are in100m

the east (ie 25RA runway corridor) experienced headwindloss of 15 knots at a height of about 300 to 400 feet Thisheadwind loss is successfully captured by GLYGA based onthe wind data from the north-runway LIDAR as shown inFigure 7 In general the headwind profile takes on a shape ofa rotated ldquoSrdquo

In order to see the performance of AVM in this windshearcase the AVM-simulated GLYGA at 04 UTC 21 July 2015based on the forecast initialized at 00 UTC 21 July 2015 isgiven in Figure 8 It could be seen that AVM-GLYGA forecastthe occurrence of terrain-induced windshear over a numberof runway corridors In particular over 25RA the headwindprofile also takes on the shape of a rotated ldquoSrdquo though theheadwind change is less abrupt and occurs over a longerdistance as compared with the actual LIDAR observationsin Figure 7 Nonetheless AVM appears to have the skill offorecasting terrain-induced windshear several hours aheadeven in a case without temperature inversions inside theboundary layer of the atmosphere

The simulated surface wind by AVM is shown in Figure 9It could be seen that the surface winds are rather uniformwhich is consistent with the actual observations (not shown)As a result just based on the surface winds only the low-levelwindshear is not noticeable This points to the importance ofmeasuring upper air winds within the boundary layer usingremote-sensing technique such as a Doppler LIDAR

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158

Hei

ght (

m)

2000180016001400120010008006004002000

6789101112131415161718

Longitude along transect (deg)

(a)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


6810121416182021222324

(b)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


minus3minus25minus2minus15minus1minus050051152253

(c)

Figure 6 The vertical cross section (along the line given inFigure 5) (a) the north-south component of the wind (b) the windspeed and (c) the vertical velocity

The vertical cross section across the eastern approachto the north runway is shown in Figure 10 The wind speeddistribution is shown in this figure It could be seen that forthe higher headwind at about 1 nautical mile away from therunway end (eastern end of the north runway) there is a low-level jet in the southwesterly wind Such information is notobtained from the LIDAR in the present scanning strategy(because there is no Range Height Indicator scan alongthat direction) It can be depicted with the high resolutionnumerical weather prediction model

Apart from low-level windshear moderate turbulencewas also experienced by an aircraft at 25RA at 0307 UTC21 July 2015 EDRmap is also generated in real time based onLIDAR data [11] and it is given in Figure 11 The formulationof LIDAR-based EDR calculation could be found in thepioneering work of Frehlich et al [12] Though the range of


20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Distance from runway end (NM)minus2 minus1 0 1 2 3 4


25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD

Figure 7 The GLYGA display at the time of low-level windshear The left hand side is the 3-degree conical scan of radial velocity of theLIDAR and the curves in the middle are the headwind profiles (headwind refers to the landing direction of the aircraft in the respectiverunway) The significant windshear is highlighted in a blue block

Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k

Distance from runway end (NM)4 3 2 1 0 minus1 minus2

Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k

Distance from runway end (NM)

Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k


Distance from runway end (NM)43210minus1minus2

43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA

Figure 8 The AVM-GLYGA display The simulated LIDAR radial velocities are given in the middle This simulated LIDAR velocity imagemay be compared with the Plan Position Indicator (PPI) image from the real LIDAR in the left hand side of Figure 7 The forecast headwindprofiles (blue) and detected windshear locations (red blocks) are given on the two sides


HKO AVM-HKASurface zoom Tue 2015-07-21 0400 UTC


22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

Figure 9 The simulated surface wind at the time 04 UTC 21 July2015 for the model run initialized at 00 UTC 21 July 2015 Theboxes on the two sides of each runway are the locations at 1 2 and 3nautical miles away from the runway end The vertical cross sectionof Figure 10 is shown as a dotted line

Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492

Figure 10The vertical cross section of wind speed along the dottedline as shown in Figure 9 The descending of a jet is indicated by awhite arrow

the LIDAR is rather limited on that day due to high humiditynear the surface it could be roughly seen that moderateturbulence could be expected over 25RA runway corridorThe corresponding TDWR velocity image (not shown) issimilar to that shown in Figure 3(a) but the wind speedis generally lower The AVM-forecast EDR map at 3-degreeconical scan is shown in Figure 12The generation of this kindof map based on NWP output has been described in Chan[13] It is able to capture the occurrence of low-level moderateturbulence and the spatial distributions of EDR in Figures 11and 12 appear to be rather similar

5 Conclusions

Two cases of terrain-induced windshear at HKIA have beenstudied in depth in this paper In particular this is the first

20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8

minus10North-runway LIDAR

(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)

Figure 11 The LIDAR-determined EDR map at 0307 UTC 21 July2015 The scale of EDR13 is shown on the right hand side

HKO AVM-HKATue 2015-07-21 0400 UTC


22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05

Forecast EDR13 (m23sminus1)

EDR on 3 deg PPI

Figure 12 The simulated EDR map for 3-degree conical scan of theLIDAR

time that simulation of terrain-inducedmicroburst is studiedfor Hong Kong Also the windshear cases occur at a timewithout temperature inversion in the thermodynamic profileand the performance of a high resolution numerical modelin such conditions is examinedThemodel is found to repro-duce thewindshear features quitewell It also offers other data(such as vertical velocity and vertical cross section across thewindshear features) that provide further information aboutthe airflow


The performance of AVM in other kinds of windshearat HKIA would be studied in the future In particular theapplication value of AVM-GLYGA would be studied morecomprehensively using a larger database of pilot windshearreports

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] T L Keller S B Trier W D Hall R D Sharman M Xu and YLiu ldquoLee waves associated with a commercial jetliner accidentatDenver International Airportrdquo Journal of AppliedMeteorologyand Climatology vol 54 no 7 pp 1373ndash1392 2015

[2] C M Shun and S S Y Lau ldquoTerminal Doppler Weather Radar(TDWR) observation of atmospheric flow over complex terrainduring tropical cyclone passagesrdquo inMicrowave Remote Sensingof the Atmosphere and Environment II vol 4152 of Proceedingsof SPIE Sendai Japan December 2000

[3] C M Shun and D B Johnson ldquoImplementation of a terminalDoppler weather radar for the new Hong Kong internationalairport at Chek Lap Kokrdquo in Proceedings of the 6th Conferenceon Aviation Weather Systems Dallas Tex USA January 1995

[4] CM Shun andPWChan ldquoApplications of an infraredDopplerlidar in detection of wind shearrdquo Journal of Atmospheric andOceanic Technology vol 25 no 5 pp 637ndash655 2008

[5] S D Mobbs S B Vosper P F Sheridan et al ldquoObservations ofdownslope winds and rotors in the Falkland IslandsrdquoQuarterlyJournal of the Royal Meteorological Society vol 131 no 605 pp329ndash351 2005

[6] W C Skamarock J B Klemp J Dudhia et al ldquoA descriptionof the advanced research WRF version 2rdquo NCAR Tech Notes468+STR 2005

[7] P W Chan and K K Hon ldquoPerformance of super high resolu-tion numerical weather predictionmodel in forecasting terrain-disrupted airflow at the Hong Kong International Airport casestudiesrdquo Meteorological Applications vol 23 no 1 pp 101ndash1142016

[8] W-K Wong C-S Lau and P-W Chan ldquoAviation model afine-scale numerical weather prediction system for aviationapplications at the Hong Kong international airportrdquo Advancesin Meteorology vol 2013 Article ID 532475 11 pages 2013

[9] S B Vosper H Wells J A Sinclair and P F Sheridan ldquoAclimatology of lee waves over the UK derived from modelforecastsrdquo Meteorological Applications vol 20 no 4 pp 466ndash481 2013

[10] A Boilley and J-F Mahfouf ldquoWind shear over the Nice CotedrsquoAzur airport case studiesrdquo Natural Hazards and Earth SystemSciences vol 13 no 9 pp 2223ndash2238 2013

[11] P W Chan ldquoGeneration of an eddy dissipation rate map at theHong Kong International Airport based on Doppler lidar datardquoJournal of Atmospheric and Oceanic Technology vol 28 no 1pp 37ndash49 2011

[12] R Frehlich S M Hannon and S W Henderson ldquoCoherentDoppler lidar measurements of wind field statisticsrdquo Boundary-Layer Meteorology vol 86 no 2 pp 233ndash256 1998

[13] P W Chan ldquoAtmospheric turbulence in complex terrainverifying numerical model results with observations by remote-sensing instrumentsrdquoMeteorology andAtmospheric Physics vol103 no 1 pp 145ndash157 2009

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However besides thunderstorms terrain-disrupted airflowcan also bring about microburst called the terrain-inducedmicroburst if the headwind loss is found to reach 30 knotsor more and in rain for example in tropical cyclone orsouthwest monsoon situation One case of terrain-inducedmicroburst has been documented in Shun and Lau [2] whichdiscusses terrain-induced microburst in neutral atmosphericcondition as associated with the strong winds of a tropicalcyclone In the present paper this kind of microburst insouthwest monsoon is considered but in terms of prevailingwind flow atmospheric boundary layer structure and theorientationlocation of terrain-induced microburst the twocases are rather similar

In order to monitor low-level windshear and turbulenceat HKIA the Hong Kong Observatory (HKO) operates asuite of meteorological equipment at the airport area ATerminal DopplerWeather Radar (TDWR) has been runningto the northeast of the airport to monitor the change ofradial velocity in rain Since the radar beam is orientedalong the runway the radial velocity change may be takenas a headwindtailwind change It is a C band area withsignificant sidelobe depression so that it could be used tomeasure rain drop return signals close to the sea and landsurfaces In nonrainy weather conditions the Doppler LightDetection and Ranging (LIDAR) systems could be used forwindshear and turbulence detection There are two LIDARsystems running at HKIA each serving a particular runwayof the airport A laser beam with a wavelength of about 2microns is used and dust and aerosols in the air are tracked inorder to measure the wind The TDWR and LIDAR systemsare used for real-time detection of low-level windshear andturbulence Their technical details and applications couldbe found in Shun and Johnson [3] and Shun and Chan[4] respectively Observations of terrain-disrupted airflow inother areas of complex terrain could be found in the literaturefor example Mobbs et al [5]

Apart from detection-based service the Observatoryalso attempts to forecast the changes in low-level wind Inparticular an aviation model (AVM) based on WeatherForecast and Research (WRF) model [6] has been runningfor the airport area with a spatial resolution down to 200mThe output wind data are ingested into the LIDAR windshearalerting algorithm also called the glide-path scan windshearalerting algorithm (GLYGA) to forecast the occurrence oflow-level windshearThe low-level turbulence is predicted bydirectly outputting the forecast EDR based on the large eddysimulation (LES) boundary layer parameterization schemeThe model has been found to be successful in predictingterrain-disrupted airflow in stable boundary layer includingFoehn wind and mountain wave The configuration of AVMand its application for stable boundary layer flow could befound in Chan andHon [7] An account of the earlier versionof the model is given in Wong et al [8] Lee waves in otherareas of complex terrain and the forecast of such waves couldbe found in Vosper et al [9] Terrain-induced windshearhas been studied for other airports using high resolutionnumerical model for example in Boilley and Mahfouf [10]Orographic effects (ie valley breezes and hill effects) aresimulated very well in the high resolution model and could

lead to a better prediction of vertical windshear or localturbulence

In this paper a number of new applications of AVMare described It is used for a case without temperatureinversions in the boundary layer basically in the summer timeof southern China to see its performance in predicting theterrain-disrupted airflow and thus low-level windshear andturbulence that would be crucial to the operating aircraftat HKIA Also this is the first time that terrain-inducedmicroburst is forecast and the structure of this kind ofmicroburst is studied in slightly greater depth by looking atthe vertical cross section of the model simulated wind fieldIt is hoped that the paper would be a useful reference forother airports in which terrain-disrupted airflow would beone crucial factor in their operations particularly about thedetection and forecasting of the windshear and turbulenceunder similar atmospheric conditions It is noted that thispaper only discusses one kind of low-level windshear associ-ated with terrain-disrupted airflow namely boundary layerwithout temperature inversion in the summer time whichis rather typical Windshear can also occur in Hong KongInternationalAirport (and in fact farmore frequent) in springtime in the presence of temperature inversions inside theatmospheric boundary layer

The boundary layer in Hong Kong mostly has a height ofabout 1 to 2 km above ground It may be determined from theoccurrence of temperature inversion in the radiosonde datafor example trade wind inversion In the spring time therecan be temperature inversion associated with the cooler con-tinental airmass near the surface undercutting the warmermaritime airmass aloftThe heights of such inversions can bein the order of 1 km above sealand surface In the previouspapers (eg Chan and Hon [7]) terrain-disrupted airflowoccurs with the appearance of temperature inversion withinthe boundary layer This paper will discuss terrain-disruptedairflow without the presence of temperature inversion insidethe atmospheric boundary layer This kind of situation mayoccur in summer time and can be rather typical under theinfluence of strong southwest monsoon

2 Background Meteorological Condition

The surface isobaric chart at 00 UTC of the day namely21 July 2015 is shown in Figure 1 There is surface troughof low pressure over inland areas of southern China Alongthe coast the strong southwest monsoon is prevailing whichcould favour the occurrence of terrain-disrupted airflow atHKIA

The upper air meteorological condition may be revealedby the upper air ascent (radiosonde) launched at Kingrsquos Parkwhich is located at about 20 km to the east of the airportat 00UTC of the day The vertical profiles of the weatherelements can be found in Figure 2 It could be seen that thewinds below 2000m amsl are basically southwesterly Thewind speed profile suggests that between 600m and 1700mamsl there is a band with wind speed greater than 20ms Asa result strong southwesterly winds prevailed in the southernChina regionThe temperature and humidity profiles are alsogiven in Figure 2 together with the potential temperature


Hong Kong










Hei

ght (

m am

sl)200019001800170016001500140013001200110010009008007006005004003002001000

Direction (deg)0 30 60 90 120 150 180 210 240 270 300 330 360

(a)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000

Speed (ms)0 5 10 15 20 25 30

(b)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000



(c)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000569 57 571 572 573 574 575

N = 0016 U = 270

N = 0009U = 377

N = 0012U = 532

N = 0008U = 328

ln 120579

(d)








Siu Ho Wan1

23

45

6 7

A

B

1998400

3998400

2998400

4998400

5998400

6998400 7

998400

(Kno

t)


(a)

A B1 2 3 4 5

(b)

4 4998400

(c)

1 1998400

(d)




Tung Chung

Siu Ho Wan



22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

10 15 20 25 30 35 40 45 50 55 60 65 70






11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158

Hei

ght (

m)

2000180016001400120010008006004002000

6789101112131415161718


(a)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


6810121416182021222324

(b)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158



(c)





20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0



25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k



43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA





22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Hong Kong










Hei

ght (

m am

sl)200019001800170016001500140013001200110010009008007006005004003002001000

Direction (deg)0 30 60 90 120 150 180 210 240 270 300 330 360

(a)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000

Speed (ms)0 5 10 15 20 25 30

(b)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000



(c)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000569 57 571 572 573 574 575

N = 0016 U = 270

N = 0009U = 377

N = 0012U = 532

N = 0008U = 328

ln 120579

(d)








Siu Ho Wan1

23

45

6 7

A

B

1998400

3998400

2998400

4998400

5998400

6998400 7

998400

(Kno

t)


(a)

A B1 2 3 4 5

(b)

4 4998400

(c)

1 1998400

(d)




Tung Chung

Siu Ho Wan



22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

10 15 20 25 30 35 40 45 50 55 60 65 70






11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158

Hei

ght (

m)

2000180016001400120010008006004002000

6789101112131415161718


(a)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


6810121416182021222324

(b)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158



(c)





20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0



25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k



43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA





22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Hei

ght (

m am

sl)200019001800170016001500140013001200110010009008007006005004003002001000

Direction (deg)0 30 60 90 120 150 180 210 240 270 300 330 360

(a)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000

Speed (ms)0 5 10 15 20 25 30

(b)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000



(c)

Hei

ght (

m am

sl)

200019001800170016001500140013001200110010009008007006005004003002001000569 57 571 572 573 574 575

N = 0016 U = 270

N = 0009U = 377

N = 0012U = 532

N = 0008U = 328

ln 120579

(d)








Siu Ho Wan1

23

45

6 7

A

B

1998400

3998400

2998400

4998400

5998400

6998400 7

998400

(Kno

t)


(a)

A B1 2 3 4 5

(b)

4 4998400

(c)

1 1998400

(d)




Tung Chung

Siu Ho Wan



22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

10 15 20 25 30 35 40 45 50 55 60 65 70






11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158

Hei

ght (

m)

2000180016001400120010008006004002000

6789101112131415161718


(a)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


6810121416182021222324

(b)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158



(c)





20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0



25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k



43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA





22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Siu Ho Wan1

23

45

6 7

A

B

1998400

3998400

2998400

4998400

5998400

6998400 7

998400

(Kno

t)


(a)

A B1 2 3 4 5

(b)

4 4998400

(c)

1 1998400

(d)




Tung Chung

Siu Ho Wan



22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

10 15 20 25 30 35 40 45 50 55 60 65 70






11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158

Hei

ght (

m)

2000180016001400120010008006004002000

6789101112131415161718


(a)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


6810121416182021222324

(b)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158



(c)





20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0



25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k



43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA





22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Tung Chung

Siu Ho Wan



22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E

10 15 20 25 30 35 40 45 50 55 60 65 70






11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158

Hei

ght (

m)

2000180016001400120010008006004002000

6789101112131415161718


(a)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158


6810121416182021222324

(b)

Hei

ght (

m)

2000180016001400120010008006004002000

11394306

11394656

11395007

11395357

11395706

11396056

11396407

11396757

11397457

11397107

11397807

11398158



(c)





20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0



25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k



43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA





22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


20150721 031756 UTC

Velo

city

(ms

)

23

20

17

14

11

8

5

2

minus2

minus5

minus8

minus11

minus14

minus17

minus20

minus23

30 deg PPI

Hea

dwin

d (k

t)

40

30

20

10

0

minus10

Hea

dwin

d (k

t)

30

20

10

0

minus10

minus20

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0

Alti

tude

(ft)

6000

5000

4000

3000

2000

1000

0



25RA

25LA

Last run

20150721 032000

25RA-14K 2MF

25RD

25LA

25LD


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40 Hea

dwin

d (k

t) 0

minus10

minus20

minus30

minus40

Hea

dwin

d (k

t)

0

10

minus20

minus10

minus30

minus40

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 5040

30

20

10

Alti

tude

(ft)4k

3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Hea

dwin

d (k

t) 50

40

30

20

10

Alti

tude

(ft)

4k3k2k1k0k


Alti

tude

(ft)

4k3k2k1k0k

Alti

tude

(ft)4k

5k

3k2k1k0k



43210minus1minus2

43210minus1minus2

43210minus1minus2

07LA

07RA

25RD

25LD

07LD

07RD

25RA

25LA





22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in




22∘22

998400N

22∘20

998400N

22∘18

998400N

22∘16

998400N

113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E


Hei

ght (

m)

1000

800

600

400

200

0

891011121314151617181920


11390273

11390954

11391635

11392316

11393679

1139436

11392998

11395722

11395041

11396404

11397086

11397767

11398448

11399129

11399811

11400492



5 Conclusions


20150721 030700 UTC

Rang

e (km

)

10

8

6

4

2

0

minus2

minus4

minus6

minus8


(30 deg PPI scan)

HKO LIDAR EDR04750450042504000375035003250300027502500225020001750150012501000075005000250000

EDR13

(m23

sminus1)




22∘24

998400N

22∘20

998400N

22∘22

998400N

22∘18

998400N

22∘16

998400N

22∘14

998400N

113∘50

998400E 113∘52

998400E 113∘54

998400E 113∘56

998400E 113∘58

998400E 114∘E

0 005 01 015 02 025 03 035 04 045 05


EDR on 3 deg PPI







References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in





References























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in










Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

Research Article Observation and Numerical Simulation of ...

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