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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
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
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
Numerical Weather Prediction
NWP impacts, with error measures restricted to the Australian region
Courtesy of Chris Tingwell, BoM
atrad.com.au
Numerical Weather Prediction
Courtesy of Chris Tingwell, BoM
• Observation density
• Prevailing west to eastweather pattern
• Height coverage
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Numerical Weather Prediction
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
Courtesy of Chris Tingwell, BoM
• Superior ST heightcoverage contributingmore observations
• Legacy systems 2 km
atrad.com.au
Numerical Weather Prediction
Courtesy of Chris Tingwell, BoM
atrad.com.au
Numerical Weather Prediction
SatelliteUpper AirSurface
Courtesy of Chris Tingwell, BoM
atrad.com.au
Numerical Weather Prediction
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
Numerical Weather Prediction
• Most BoM profilers now available on EUMETNET
http://eumetnet.eu/radar-wind-profilers
atrad.com.au
Numerical Weather Prediction
* Wind speed bias* U bias* V bias
Information courtesy of Maxime Hervo, EUMETNET monthly report
atrad.com.au
Numerical Weather Prediction
* 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 Retrievals
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
Precipitation Retrievals
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
Precipitation Retrievals
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
Precipitation Retrievals
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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
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Real Time Retrievals
• 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
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Real Time Retrievals
• 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
Real Time Retrievals
• 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
Real Time Retrievals
• Developing pre-retrieval quality control algorithms to identify relevant portions of the spectrum
Identify all peaks in spectrum
• Clear – air• Precipitation• Interference
If CA & precipidentified
Find merger between peaks
atrad.com.au
Real Time Retrievals
• Developing pre-retrieval quality control algorithms to identify relevant portions of the spectrum
Identify all peaks in spectrum
• Clear – air• Precipitation• Interference
If CA & precipidentified
Find merger between peaks
Perform deconvolution
atrad.com.au
Interference Removal
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Interference Removal
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Threshold Procedure
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Threshold Procedure
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Threshold Procedure
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Threshold Procedure
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Threshold Procedure
atrad.com.au
Threshold Procedure
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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
Baden Gilbert, Honours Student, University of Adelaide
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.
Baden Gilbert, Honours Student, University of Adelaide
atrad.com.au
Fitting Routine
• While the spectra are accurately described, one size fits all guesses to locations and widths proved difficult
Baden Gilbert, Honours Student, University of Adelaide
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
Baden Gilbert, Honours Student, University of Adelaide
atrad.com.au
Fitting Routine
ST radar BL radar
Baden Gilbert, Honours Student, University of Adelaide
atrad.com.au
Results – TC 2 February 2016
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Results – TC 2 February 2016
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Results – TC 2 February 2016
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Results – TC 2 March 2012
Spectra from consecutive time stamps
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Results - 4 July 2016
Adelaide
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Results - 4 July 2016
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Results - 4 July 2016
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Results - 4 July 2016
Missing retrievals?
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Results - 4 July 2016
atrad.com.au
Results - 4 July 2016
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
Real Time Retrievals
• 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
Real Time Retrievals
• 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
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