The Australian Wind Profiler Network - · The Australian Wind Profiler Network Bronwyn 1,2Dolman ,...

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The Australian Wind Profiler Network

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

1ATRAD Pty Ltd20 Phillips St Thebarton

South Australiawww.atrad.com.au

2University of Adelaide, Australia

3Australian Government Bureau of Meteorology

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Australian Profiler Network

Ceduna

Tennant Creek

Buckland Park

Carnarvon

Davis Station

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Weather Radar

Meteorological InstrumentationRemote Balloon Launcher

Wind Profiling Radar

Tennant Creek

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

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• Currently all VHF systems (55 MHz)– Boundary Layer Profiler (BLP) 8 km coverage– Stratospheric Tropospheric Profiler (STP) 20 km coverage– System design is modularwith most components shared

Power Amplifiers 80 kW STP

Transceiver / signal

processing

Beam Steering

Combiner

Antennas

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Boundary Layer Profilers

• Spaced Antenna– Full Correlation Analysis– 27 Yagi antennas arranged in 3 groups of 9– 0.7 spacing

Frequency 55 MHz (range 30 ‐ 64 MHz)

Power 12 kW (3 4 kW modules)

Receiver 3 coherent (complex) channels

Acquisition Virtex‐4 FPGA

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Boundary Layer Profilers

• Spaced Antenna– Full Correlation Analysis– 27 Yagi antennas arranged in 3 groups of 9– 0.7 spacing

Low High

Pulse Width 100 m 500 m

PRF 20 000 Hz 10 000 Hz

Range 0 – 7 km 0 – 14 km

Sampling Interval 100 m 250 m

Dwell Time 55 s 55 s

Coherent Integrations 1000 500

Spectral Points 1100 1100

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Stratospheric Tropospheric Profilers

• Doppler Beam Steering Analysis– 144 Yagi antennas arranged on a 12 x 12 square grid– 0.7 spacing– Phase delays to steer beam

Frequency 55 MHz (range 30 – 64 MHz)

Power 80 kW (24 4 kWmodules)

Receiver 3 coherent (complex) channels (1 used)

Acquisition Virtex‐4 FPGA

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Stratospheric Tropospheric Profilers

• Doppler Beam Steering Analysis– 144 Yagi antennas arranged on a 12 x 12 square grid– 0.7 spacing– Phase delays to steer beam

Low High

Pulse Width 250 m 1000 m

PRF 14 000 Hz 6000 Hz

Range 0 – 8 km 1 – 20 km

Sampling Interval 100 m 200 m

Dwell Time 55 s (per beam) 55 s (per beam)

Coherent Integrations 700 150

Spectral Points 1100 2200

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Wind Measurements

Doppler

FCA X 15

Averaging interval: 30 mins

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Wind Measurements

Doppler

QualityControl

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Wind Measurements

Doppler

QualityControl

Wind Estimate

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Wind Measurements

Doppler

QualityControl

Wind Estimate

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Wind Measurements

Doppler

QualityControl

Wind Estimate

Output to user

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Wind Measurements

• Verified at each site against sondes

Sonde magnitude against profilerZonal and meridional comparison

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Forecasters

• 30 minute average data available to Australian forecasters– Gradient and steering winds, jet onset time and duration– Aviation forecasts– Fire weather

20 km Tennant Creek 80 kW STP high mode

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Global data use

• Most BoM profilers now available on EUMETNET

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

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ACCESS NWP

• Based on Met Office Unified Model and 4D‐Var data assimilation

• Provides the BoM with operational forecasts

Global and RegionalACCESS systems assimilate a wide range of meteorological observations in six‐hour cycles

Courtesy of Chris TingwellBoM

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ACCESS Forecast Sensitivity to ObservationsSignificant new technique in which the forecast error reduction in a 24 hour forecast due to data assimilation can be split up and attributed to each individual assimilated observation.

Forecast error is measured by a global energy norm (in J/kg).

Over several weeks, the reduction of forecast error due to observing systems, instruments, groups of observations etc. can be aggregated and compared.

Data Assimilation4D‐Var

Observations

ForecastT + 24h

ForecastT + 30h

ForecasterrorT + 24h

ForecasterrorT + 30h

Analysis

Change in forecast error

Change in forecast error due to analysis

Change in forecast error due to each observation

Adjoint PF model

Adjoint VAR

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Australian Upper Air Observing Network

Halls CreekWINPRO & PILOT

WilliamtownSydney

TEMP: radiosonde observations of temperature, moisture, wind (once/twice per day)PILOT: tracked balloon flights – wind only (once/twice per day)WINPRO: wind profilers (hourly)

Labelled stations used for comparisons here

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Australian Upper Air Observing Network24 hour forecast error reduction in the global ACCESS system due to observations in the Australian Upper Air network aggregated over 10 weeks (more negative means more forecast error reduction).

Wind profilers contribute less than the impact of the radiosonde "TEMP" observations, but rather more than the "PILOT" wind observations.

WINPRO observation impacts are less on a per observation basis (2ndpanel) but this is counter‐balanced by their being much more frequent.

Forecast Impact/day (J/kg)

Forecast Impact/observation (J/kg)

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Australian Upper Air Observing NetworkTemp impacts greatest as include measurements of temperature, humidtyand wind reported at many observation levels. Also assigned a smaller observation error in the assimilation and is thus assigned more weighting.

Per observation refers to, say, a single zonal wind measurement at a particular height at a particular time.

Density and timing of observation must be considered here. The profilers are typically located at Bureau sites and thus amidst other observations. The sondes are at a lower temporal resolution and thus add information to a region of the model which hasn’t seen an observation for up to 24 hours.

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Australian Upper Air Observing NetworkWilliamtown v. Sydney

Comparison of impacts from nearby radiosonde "TEMP" (Williamtown) and Wind profiler (Sydney) observations.

The greatest impact/observation is from the Williamtown temperature & moisture measurements, but the aggregated forecast impact from the Sydney wind profiler is almost as much as from the Williamtown radiosonde flights.

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Australian Upper Air Observing NetworkHalls Creek

Co‐located wind profiler and PILOT observations

PROFILER: hourly observations throughout day.PILOT balloon flights: twice a day at 00 UTC & 06 UTC.

WINPRO observations have greater integrated forecast impact because of much greater numbers, although the impact per observation is less.

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Current Developments

• Examining dwell time with an aim to reduce it• Turbulence estimates• Tropopause detection• Developing real‐time automatic peak detection routines– Automatically identify

and where possible or problematic, remove interference

– Trigger additional analysis such as precipitation retrievals

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

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Interference Removal

Aircraft interferenceCourtesy of Baden GilbertUoA

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Interference Removal

Aircraft interferenceCourtesy of Baden GilbertUoA

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Real Time Retrievals

Precipitation

Rainfall Clear air

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Drop Size Distribution

Precipitation

Rainfall Clear air

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Drop Size Distribution

Rain Rate Retrieval

Rainfall Clear air

Precipitation

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Conclusion

• Australian wind profiler network consists of 18 instruments across Australia and Antarctica– 11 assimilated profilers make a significant contribution to improving the forecast skill of ACCESS

• Current effort geared towards providing the best possible product for the user, and utilising data for more than wind estimates

The Australian Wind Profiler Network - · The Australian Wind Profiler Network Bronwyn 1,2Dolman ,...

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