Airborne Doppler Analysis, Quality Control, and Transmission

in 2009 and 2010

John F. GamacheNOAA/AOML/Hurricane Research Division

WP-3D Aircraft and their Radars

Airborne Doppler Radar Scanning Geometry

Courtesy of Fuqing Zhang

Quality Control of airborne Doppler data

• Remove sea surface reflection by main radar lobe• Remove noisy data• Remove side-lobe reflection from sea-surface--more

difficult in the pre-depression to tropical-storm stage. Still an area for improvement--some progress

• Automatically de-alias Doppler data (RVP-8 may simplify this process in 2010 Hurricane Season)

• Moved QC/analysis software to HRD-supplied MacBook laptops in 2009

• We are getting ready for Sigmet RVP-8 Doppler processor output in 2010 Hurricane Season, both P3s and G-IV. Debugging our software on initial test-flight data from G-IV tail Doppler radar

Data transmission to ground• Real-time analyses in form agreed upon by HRD

and NHC still sent to ftp site for polling by NHC• Analyses in full-3D form and deep vertical profiles

sent via SATCOM to AOML ftp site--will work this year on making it more accessible in real time for others--including NETCDF

• Superobs for WRF-ARW high-resolution observations were sent in real time to AOML ftp site for polling by F. Zhang and numerical collaborators, and assimilated in real time

New plans for 2010 Hurricane Season

• EMC will assimilate airborne Doppler radial velocities into parallel run of HWRF

• Quality controlled Doppler radial velocities from G-IV radar for the first time.

• HFIP modelers will assimilate Doppler superobs with modifications as necessary to present-format superobs

• NETCDF versions of airborne Doppler analyses will be made available quickly after the observations—generally within 1-2 hours

Challenges in 2010• Perfecting collection of airborne Doppler data on

NOAA G-IV• Conversion to Sigmet RVP-8

– Modifying our RVP-5 code to work with RVP-8 data files—debugging on recently-available test data

– Format of platform-specific header data for P3 not final--no real data for testing until shortly before hurricane season

• Transmission of quality-controlled data to ground--looking good at this time

NOAA G-IV Test Flight Dec 18 2009

Doppler radial Velocity

Radar Reflectivity

NOAA G-IV Test Flight Dec 18 2009

Doppler radial Velocity

Radar Reflectivity

NOAA G-IV Test Flight Dec 18 2009

Doppler radial Velocity

Radar Reflectivity

NOAA G-IV Test Flight Dec 18 2009

Doppler radial Velocity

Radar Reflectivity

G-IV TDR Operational Systems Acceptance Test

Determine from in-flight data whether Doppler radar data meet the following criteria:Accuracy of Doppler radial winds: 1m/s•Compare with WSR-88D Doppler radial observations•Compare with P3 Doppler radial observations•Sanity check--probably won’t ever get down to 1 m/s

•Errors in radar--less likely•Errors subtracting aircraft velocity--more likely•Will try to minimize INE errors by flight plan•Will also allow us to test reporting of aircraft

flight data to radar data filesOther criteria--reflectivity accuracy and sensitivity

•Compare with 88D/find lowest refl at cloud top

Wind

2010 Data transmission• Format agreed to in 2009

– Only radial velocities sent to NCO/EMC– Placeholders for reflectivity and spectral width

• Tests in 2010– Quality-controlled radials from 2008/2009 stored on P3 flying

during winter storms– Script to transfer QC-ed radial files to P3 server– Streaming of compressed data to AOC/TOC– Data was received at TOC and then at NCO– Full or nearly full QC-ed Doppler radial data may on use 1/3 or

less of new SATCOM bandwidth

2010 Data transmissioncontinued

• NCO developed translator of file received at NCO into WMO BUFR format

• Comparison of original file to that received at NCO--identical • Comparison of BUFR file to original file data--discrepancies

just found--should be easy to correct in the next week or so• NCO/EMC/AOC/RSS/HRD are ready to transmit, receive

Doppler data and store them in the NCEP BUFR for assimilation

• In the future we may be able to send full radar data stream

SummaryChallenges remain to be ready for 2010

•Perfection and acceptance of G-IV TDR•Conversion of P3 radar to RVP-8•Development of RVP-8 on P3 by 1 June•HRD I/O of RVP-8 data also tested by 1 June

•Communication of data to EMC•Initial tests look very promising•Data should be available for parallel

HWRF runs in 2010•Modification of superobs as needed for HRD to

assimilate Doppler data in its HWRF runs•Making Doppler wind analyses available to

Hurricane community in real time

Analysis software

• No significant changes in 2010--minor changes for operators of software.

• Will require revamping and modification for acceptance of RVP-8 data in 2010--in progress--perfecting code

• Improvement in the removal of side-lobe reflections off the sea surface--absolutely necessary when flying in the clear.

Making superobs• azimuthal grid resolution (around fuselage axis): 3-5

degrees depending upon radius• Radial grid resolution: 2 km• Along track resolution: 1 min = ~7-8 km• All radial velocity observations within a grid cell could

be candidates, but only 25 points closest to the grid point used

• Velocities more than 2 std dev from bin average rejected

• Bins with std dev more than 2 times the std dev of the bin std deviations rejected

• ~5000 superobs per penetration of hurricane

2009 flights with transmitted superobs

• Ana: August 19 (090816I1)—1 flight—2 superobs• Bill: August 18-August 20: 090818I1, 090819I1, 090819I2,

090820I1, 090820I2—5 flights—13 superobs• Danny: August 26-28: 090826I1, 090826I2, 090827I1,

090827I2, and 090828I1—5 flights—13 superobs• In 2009, superobs were only assimilated in real time by a

research WRF-ARW model (Fuqing Zhang, Yonghui Weng)--more HFIP modelers expected to assimilate superobs, including HRD