RMetS December 2010

North West Local Centre

www.tinyurl.com/nwrmets

Welcome• Weather news – The cold snap!

• Prof. Tom Choularton (Uni. Manchester)– A history of the Whitworth Observatory

• Dr. Michael Flynn (Uni. Manchester)– Instrumentation at the Whitworth Observatory

• Dr. Hugo Ricketts (Uni. Manchester)– How to interpret weather data

• Questions

• Announcements / Next Meeting

• Close – 7 pm

Weather News

Prof. Tom Choularton

•Ph.D from UMIST in 1977 in Atmospheric Physics

•Appointed to the academic staff in 1979.

•Chair in 1995 and Head of UMIST Physics Dept. during the merger of UMIST and Manchester University and head of SEAES until this year.

•2008 - awarded RMetS Mason Gold Medal for contributions to the understanding of processes that determine variability and predictability of weather and climate.

•Tom continues to lead an active research group studying the microphysics of mixed phase clouds and cloud aerosol interactions.

Reopening of the Whitworth Meteorological Observatory

The Whitworth ObservatoryHistory

1. Meteorological Observatory in Whitworth Park started operation in August 1892.

2. In 1893 the Residuary Legatees of the late Sir Joseph Whitworth, the Manchester Whitworth Institute and the Owens College endowment an agreement for the maintenance of the “Meteorological Observatory in Whitworth Park”

3. This observatory was to serve as a source of scientific and popular interest and of education. Data from the Whitworth Observatory were provided by the University to the Guardian newspaper for daily and weekly weather reports for the benefit of Manchester citizens. They were also forwarded to the Met Office

4. Burned down in 1958 under mysterious circumstances 5. It was agreed in 2003 that the shares in the fund and the unspent balance

should be transferred to the School of Earth, Atmospheric & Environmental Science (SEAES) since we "do work relevant to the purposes listed in the original 1893 Agreement."

Sir Joseph Whitworth 1803 – 1887Mechanical Engineer

Sir Arthur Schuster (1851-1934)

Observations in 1906• Read at 9 a.m. and 9 p.m.

- Barometer. - Dry Bulb Thermometer - Wet Bulb Thermometer- Maximum Thermometer- Minimum Thermometer- Black Bulb Thermometer- Grass Thermometer- Rain Gauge

• Self recording instruments. - Barograph. - Robinson Anemometer. - Dines-Baxendell Pressure Tube - Anemometer and Anemograph- Sunshine Recorder.

An Early Report on Urban Meteorology

• Comparison of Observations of Temperature taken at two stations in Manchester from December 4th, 1892, to January 28th, 1893. By J. Wilson. Communicated by Arthur Schuster, Ph.D., F.R.S., F.R.A.S.

• Published in Memoirs and Proceedings of The Manchester Literary and Philosophical Society, Series 4, Vol 7, pp 160-168, 1893.

Maxima. • Average maxima at Whitworth Park 41.4 F• Average maxima at Oldham Road, 40.2°F.

• January bright sunshine Whitworth Park 17hrs, 20min • January bright sunshine Oldham Road l0hrs, 45mins

• January there does not appear to be any connection between the differences in the maxima and the differences in the amount of bright sunshine on a given day. The greatest divergence 8.8°F between the maxima occurs on Jan. 5th.

. Minima. • The minima show a much greater difference than do the maxima,• Daily average Whitworth Park 29.5°F• Oldham Road daily average 32.5F• The days marked by the greatest divergences are December 5,

December 6, January 4, January 5, and January 6, these being also the days of greatest cold.

Dr. Michael Flynn

•PhD from UMIST in 2000

•Now an Experimental Officer in SEAES

•Instrumental development and measurement techniques

•Broad research interests – Land-atmosphere fluxes, cloud and aerosol measurement etc

The New Whitworth Observatory

Michael Flynn

Introduction

• Location• Measurements Made• Instruments Used• Operating Principles of Selected Instruments• Data Availability• Acknowledgements

Location Map

Location

Location• Details

– Roof of George Kenyon Building N53.467374, W2.232006, Alt 43m

– Rooftop Height 46m AGL– Instrument Heights 1-5m above roof

• Choice of Site– Secure– Measurements unaffected by surrounding

buildings– Wind data representative of flow ventilating the

city

Measurements MadeParameter Range Resolution Accuracy Rate

Wind Speed 0-65m/s 0.01m/s 1.5%@12m/s 20Hz

Wind Direction 0-359deg 0.1deg 2%@12m/s 20Hz

Temperature -40 - +60C 0.1C 0.1C 1Hz

Relative Humidity 0-100%RH 0.1% 1.5% 1Hz

Barometric Pressure 500-1100hPa 0.01hPa 0.3hPa 1Hz

Direct and Diffuse Solar Radiation (310-2800nm)

0-1600 W/m2 2% 5s

Longwave Radiation (4.5-42um) -400 – 100 W/m2 5% 18s

Meteorological Visibility 10m – 75Km 2% 60s

Precipitation Typedrizzle (also freezing), rain (also freezing), hail, snow,snow grains / ice needles, soft hail / ice grains

60s

Precipitation Rate 0.005 – 250mm/hr 0.001mm/hr <10% 60s

Precipitation size distribution 0.16 – 8mm 22 bins 60s

Precipitation velocity distribution 0.2 – 20m/s 20 bins 60s

Cloud Height 10 – 8200m 3m 7.5m 60s

Instruments Used

Sonic Anemometer

Advantages• High accuracy (1.5%)

• Good resolution (1cm/s)

• Able to measure low wind speed without stalling

• Fast response rate (20Hz) – able to capture atmospheric turbulence

• 3d wind speed – can derive direction and wind angle

• No moving parts

Sonic Anemometer

Laser Distrometer

Laser Distrometer

Advantages .• Good temporal resolution at all precipitation rates (1min)

• Identification of onset of precipitation

• Measurement of particle size distribution and particle velocity

• Recognition of different precipitation types (drizzle, rain, hail, snow)

•No moving parts, cannot get blocked

Precipitation Recognition MatrixPa

rticl

e Fa

ll Sp

eed

Particle Diameter

Figures from “INVESTIGATIONS INTO THE IMPROVEMENT OF AUTOMATED PRECIPITATION TYPE OBSERVATIONS AT KNMI” by Marijn de Haij and Wiel Wauben 2010.

Laser Distrometer – Precipitation TypeRain Snow

Parti

cle

Fall

Spee

d

Parti

cle

Fall

Spee

dParticle Diameter Particle Diameter

Present Weather Sensor

Capability• Extinction Coefficient

• Meteorological Optical Range

• Presence of cloud/fog/haze

• Precipitation rate and type

• Temperature

Light Transmission and Extinction

Scattering

Absorption

Extinction = Scattering + Absorption

Meteorological Optical Range = 3.00/Extinction Coefficient

Meteorological Optical Range

The path length in the atmosphere required to reduce the luminous flux in a collimated beam from an incandescent lamp at a colour temperature of 2700K to 0.05 of its original value.

Where β is the extinction coefficient

Daytime Visual Range

The limiting distance at which a black target is visible against the horizon sky.

Koschmieder’s Law (1924)

Where β is the extinction coefficient

Night-time Visual Range

The distance at which an observer can see lights through the atmosphere at night.

Allard’s Law (1876)

Where Et is the observers illuminance threshold and β is the extinction coefficient

Visibility and Meteorological Optical Range

2V

IeE

V

t

00.3

RV

00.3

MOR

Present Weather Sensor - Schematic

Present Weather SensorExtinction Coefficient• Calculated from measured scattering coefficient (45deg forward)

• Assume all extinction is due to suspended particles (no scattering by gases – valid for optical range < 100Km)

• Assume all extinction is due to scattering (no absorption – valid for most environments except under very heavily polluted conditions)

• Between 35 and 55 deg scattering angle, very little variation in scattering phase function for different types of haze and fog

• Haze/Fog calibration still valid in snow for 45deg scattering angle

• Haze/Fog calibration overestimates extinction coefficient in rain

Precipitation• Integrated particle size distribution used for precipitation intensity

• Particle size and velocity matrix and forward/back scatter ratio used for precipitation recognition.

Ceilometer

Capability• Determination of cloud height using LiDAR principle

• Range 30-8300m

• Vertical resolution 3m

• Time resolution 2s max (typically 15s)

• Algorithm for cloud cover

Ceilometer

Ceilometer Data

Data Availability• Website

http://www.cas.manchester.ac.uk/restools/whitworth/– Current Plots– Current Table– Archive Plots

• Future Plans– Display in Manchester Museum– Mobile phone app etc.

Acknowledgements

• Sir Joseph Whitworth (1803-1887)• Carl Dixon and Barry Gale – SEAES Workshop• Estates Team• Dr. Keith Bower, Prof. Martin Gallagher –

SEAES

Dr. Hugo Ricketts

•Ph.D from Uni Manchester 2010 – Ozone Lidars

•NCAS Research Scientist

•Lidar instrument developer

•Boundary layer processes

•Aerosol transport / Iceland Volcano

Yesterday - 6th Dec

© University of Manchester

Relative HumidityTemperature Dew Point Temp.

Solar Radiation Terrestrial Radiation Visibility

© NERC Satellite Receiving Station / University of Dundee© NERC Satellite Receiving Station / University of Dundee

Yesterday 2:53aminfra-red


Yesterday 12:47pminfra-red


Yesterday 12:47pm

visible


Yesterday 6:48pminfra-red


Today 12:27pminfra-red

Announcements

• Feedback forms

• E-mail list

• Weather balloon video!

• RMetS membership info

• Suggestions welcome?

http://thebarometer.podbean.com

Next Meeting(25th Jan 2011 – Renold D9, 6pm)

• Dr. Lindsay Bennett (Uni. Leeds) – A real life storm chaser! – The Verification Of Rotation in Tornadoes

Experiment (VORTEX2), USA 2009/2010. – Largest study ever undertaken to study

tornadoes with a mobile armada of over 100 scientists and 40 research vehicles.

– Lindsay will talk about her role in the team and some of her experiences of getting up close and personal with severe weather

RMetS December 2010

Documents

Transcript of RMetS December 2010