rainfall measurements using the australian wind profiler ... · rainfall measurements using the...

Rainfall Measurements using the Australian Wind Profiler Network

Bronwyn Dolman1,2, Iain Reid1,2, Tom Kane3 and Chris Tingwell3

1ATRAD Pty Ltd20 Phillips St Thebarton

South Australiawww.atrad.com.au

2University of Adelaide, Australia3Australian Government Bureau of Meteorology

http://www.atrad.com.au/

atrad.com.au

Australian Profiler Network

Ceduna

Tennant Creek

Buckland Park

Carnarvon

Davis Station

atrad.com.au

Australian Profiler Network

Weather Radar

Meteorological InstrumentationRemote Balloon Launcher

Wind Profiling Radar

Tennant Creek

• Complement existing meteorological technology providing continuous profiles of the atmosphere in the vertical columnabove the instrument

atrad.com.au

Wind Measurements

Doppler

FCA

QualityControl

QualityControl

X 15

Averaging interval: 30 mins

atrad.com.au

Wind Measurements

Doppler

FCA

QualityControl

QualityControl

X 15

Wind Estimate

Wind Estimate

Averaging interval: 30 mins

atrad.com.au

Wind Measurements

Wind Estimate

Wind Estimate

BUFR

BUFR

Output to user

Doppler

FCA

atrad.com.au

Wind Measurements

• Verified on install at each site against sondes

• Excellent data set for additional research

Zonal and meridional comparison Sonde magnitude against profiler

atrad.com.au

Wind Measurements

Location InstalledNumber

of sondesZonal line of

best fitMeridional line

of best fit

Ceduna 2011 94 1.02 1.01

Mildura 2012 41 1.00 1.05

Cairns 2013 41 0.96 1.01

Coffs Harbour 2013 25 0.99 1.00

Mackay 2016 41 0.99 1.03

Tennant Creek 2012 62 Low 1.00 0.97

High 0.96 0.93

Carnarvon 2012 58 Low 1.00 1.00

High 0.97 0.93

Halls Creek 2015 100 Low 0.97 0.93

High 0.97 0.93

Longreach 2017 45 Low 0.97 0.95

High 0.97 0.93

Boundary Layer Profilers

Stratospheric Tropospheric Profilers

atrad.com.au

Wind Measurements

Output to user

Research

Numerical Weather

Prediction

Forecasting

atrad.com.au

Forecasting

Output to user

Research

Numerical Weather

Prediction

Output to user

Research

Numerical Weather

Prediction

8 kmTennant Creek 80 kW STP low mode

06 UT 18 UT

Forecasting

atrad.com.au

Numerical Weather Prediction

• ACCESS based on Met Office Unified Model and 4D-Var data assimilation

• Provides the BoM with operational forecasts

Global and Regional ACCESS systems assimilate a wide range of meteorological observations in six-hour cycles

atrad.com.au


NWP impacts, with error measures restricted to the Australian region

Courtesy of Chris Tingwell, BoM

atrad.com.au



• Observation density

• Prevailing west to eastweather pattern

• Height coverage

atrad.com.au


Location Type Install Year

Carnarvon ST 2012

Halls Creek ST 2015

Tennant Creek ST 2012

Ceduna BL 2011

Mildura BL 2012

Sydney BL 1999

Canberra BL 2005

East Sale BL 2009

Cairns BL 2013

Coffs Harbour BL 2013

Launceston BL 2004


• Superior ST heightcoverage contributingmore observations

• Legacy systems 2 km

atrad.com.au



atrad.com.au


SatelliteUpper AirSurface


atrad.com.au


Instrument Measurement Impact Impact per cost

Radiosondes T, q, u, v 0.094 0.9

Wind Profilers u, v 0.003 2.8

AMDAR + AIREP T, u, v 0.084 16.6

Reproduced from UK Met Office “Cost-benefit studies for observing systems”

Forecasting Research Tehcnical Report No: 593August 2014

John Eyre and Rebecca Reidhttp://www.metoffice.gov.uk/media/pdf/k/n/FRTR593.pdf

atrad.com.au


• Most BoM profilers now available on EUMETNET

http://eumetnet.eu/radar-wind-profilers

atrad.com.au


* Wind speed bias* U bias* V bias

Information courtesy of Maxime Hervo, EUMETNET monthly report

atrad.com.au

Numerical Weather Prediction – 1 May 17

Information courtesy of Maxime Hervo, private communication

EUCOS Meteo-France UKMO ECMWF

Ceduna a r a r

Mildura a a a a

Cairns a r a a

Coffs Harbour a r a a

Mackay a a r r

East Sale a r r a

Canberra a r r a

Launceston a r r a

Sydney a r a a

Tennant Creek r a a a

Halls Creek r a a a

Carnarvon a r a a

Longreach a r a a

atrad.com.au

Research

• Precipitation Information

• Tropopause Detection

• Turbulence Monitoring

Alexander, S. P., Murphy, D. J. and Klekociuk, A. J., “High resolution VHF radar measurements of tropopausestructure and variability at Davis , Antarctica (69o S, 78o E)”, Atmos. Chem. Phys., 13, 3121,-3132, 2013

Holdsworth, D. A., Vincent, R. A. and Reid, I. M., “Mesospheric turbulent velocity estimation using the Buckland Park MF radar”

atrad.com.au

Precipitation Retrievals

Clear-air peak centred near 0 m/s (Bragg scatter)

Deviations from zero are the result of the mean vertical motion of the atmosphere

Width of the peak affected by beam broadening and turbulent motions within the sampled volume

atrad.com.au


Precipitation peak centred near -10 m/s (Rayleigh scatter)

Echo needs to be corrected for clear-air effects, as it is both broadened by turbulence and shifted due to the mean vertical air motion

atrad.com.au


Separate peaks, as close to minimum of merger as possible

Fit Gaussian to clear-air peak

Add tail to precipitation peak

Deconvolve using a Fourier transform

Convert to a DSD using a known fall speed to drop diameter relationship

atrad.com.au


Drop Size Distribution is the number of drops of a given size in a sampled volume of the atmosphere

Often generalised to the median drop diameter, D0

Large concentration of small drops, with a smaller number of large drops

atrad.com.au


atrad.com.au

Real Time Retrievals

• Problems can occur with

– Unclear merger point between peaks

– Fit to clear-air (spike in data or not Gaussian shaped)

– Merger between peaks incorrectly identified

atrad.com.au


• Radar and rain event dependent, but as an approximation each time stamp takes around 15 minutes to process

• ~ 10 hours work toproduce a qualitycontrolled product

atrad.com.au


• Problems can also arise due to interference, incorrectly identified peaks in extreme up/down-draughts, etc…..

• Not typically a problem in post processing, but presents a challenge for real-time operation

– How do you identify the cause of bad retrievals?

atrad.com.au


• Developing pre-retrieval quality control algorithms to identify relevant portions of the spectrum

Identify all peaks in spectrum

• Clear – air• Precipitation• Interference

atrad.com.au





If CA & precipidentified

Find merger between peaks

atrad.com.au





If CA & precipidentified

Find merger between peaks

Perform deconvolution

atrad.com.au

Interference Removal

atrad.com.au

Threshold Procedure

atrad.com.au

Fitting Routine

• Neural network approach– Peak locations are easily picked by human eye, thus an

analogue of a biological system i.e. a neural network makes sense.

– Each “node” is an analogue to a neuron in the brain – it takes in various inputs, weights them and passes an activation on

– The internal weights are set by “training” the NN – let it take a guess, tell it what the answer should be, and it will adjust it’s weights accordingly (feed-forward back-propagate NN)

– Training can take a long time, but it is very quick to evaluate once trained

Baden Gilbert, Honours Student, University of Adelaide

atrad.com.au

Fitting Routine

• Even on simulated data, performance was limited

– Would ideally train on data that has been manually classified

Purple line is the actual answer, yellow line is the guess of the NN


atrad.com.au

Fitting Routine

• Radial Basis Function Network

– Represents the spectrum as a sum of regularly spaced Gaussian functions

– Essentially acts as an advanced smoothing filter

– Allows peaks to be non Gaussian

Individual functions have no physical significance, while their sum (pink line) represents the spectrum.


atrad.com.au

Fitting Routine

• While the spectra are accurately described, one size fits all guesses to locations and widths proved difficult


atrad.com.au

Fitting Routine

• Smoothed second derivative

– Signal processing tool IGOR Pro

– Estimates noise and required boxcar width for smoothing, then uses smoothed second derivative to estimate both number of, and properties of, peaks in spectra


atrad.com.au

Fitting Routine

ST radar BL radar


atrad.com.au

Results – TC 2 February 2016

atrad.com.au

Results – TC 2 March 2012

Spectra from consecutive time stamps

atrad.com.au

Results - 4 July 2016

Adelaide

atrad.com.au


atrad.com.au


Missing retrievals?

atrad.com.au


atrad.com.au

Darwin

BoM office

ARM instrumentation

BL Profiler

BL Profiler 54.1 MHz7.5 kW27 3-element Yagi antennas, arranged in 3 groups of 9SA FCA technique to measure winds300 – 4000 m in two modes2 min resolution

atrad.com.au


• Opportunity to routinely retrieve rainfall information from wind profilers across Australia

– Analyse microphysics dictating rainfall

– Develop climatologies

– Contribute to multi-sensor approaches

atrad.com.au


• Retrieve vertical profiles of the rain rate as storm systems pass over profiler sites

atrad.com.au

Conclusion

• Australian Profiler network is now in full operation

• Data is routinely available to Australian Forecasters

• Assimilated across the globe in all major models to varied extent

• Research on profiler data continues

• Numerical Weather Prediction, and measuring the impacts of profilers (or any instrument) is highly complicated

– Future research will focus on better understanding the impacts, and thus potentially optimising profiler locations and operational settings for maximum impact

• Research is now focussed on optimising the network and its contribution to forecasting, research, global NWP, data products and multi sensor analysis

rainfall measurements using the australian wind profiler ... · rainfall measurements using the...

Documents