high quality wind retrievals for hurricanes using the seawinds scatterometer
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W. Linwood Jones and Ian Adams Central Florida Remote Sensing Lab Univ. of Central FL. High Quality Wind Retrievals for Hurricanes Using the SeaWinds Scatterometer. Presentation Outline. Hurricane Wind Vector Retrieval Issues CFRSL Hurricane Retrieval Algorithm QRad Rain Rate Algorithm - PowerPoint PPT PresentationTRANSCRIPT
High Quality Wind Retrievals for Hurricanes Using the SeaWinds Scatterometer
W. Linwood Jones and Ian AdamsCentral Florida Remote Sensing Lab
Univ. of Central FL
Presentation Outline
Hurricane Wind Vector Retrieval Issues CFRSL Hurricane Retrieval Algorithm QRad Rain Rate Algorithm Isabel and Fabian Results Conclusion
Issues with L2B Wind Vector Retrievalfor Extreme Wind Events
Wind retrievals not tuned for high wind speeds Geophysical Model Function developed for wind
speeds < 20 m/s
CFRSL Approach Tropical Cyclone GMF tuned for retrieving high wind
speeds Blended UMASS aircraft scat measurements and
NSCAT GMF
Issues with L2B Wind Vector Retrievalfor Extreme Wind Events
Egg spatial resolution @ 25 km sampling is too coarse
CFRSL ApproachUses gridded “slice sigma-o” @ 12.5 Km
sampling
25 km resolution using “eggs”
50 k
m
25 k
m
Longitude
Lat
itude
Range gated “slices” from “egg”
6 km
30 km
12.5 km
25 km
Issues with L2B Wind Vector Retrievalfor Extreme Wind Events
Rain has negative effects on wind measurementsRain attenuation lowers retrieved wind speedsVolume scattering increases retrieved wind
speeds and alters directional signaturesRain “splash” increases retrieved wind speeds
and changes anisotropic ocean surface features
MUDDH performance in hurricanes is poor
Issues with L2B Wind Vector Retrievalfor Extreme Wind Events
Rain has negative effects on wind measurements
CFRSL ApproachSimultaneous rain measurement using QRadRain attenuation and volume backscatter
correction providedRain splash effect included in GMFRain Quality Flags Provided
CFRSL Hurricane Retrieval Algorithm
“Slice” sigma-0’s for improved spatial resolution - 12.5 km
Sigma-0 minimum eye location Wind speed retrieved from individual sigma-0
(assumed spiral wind directions) Rain inferred using QRad rain rate algorithm Sigma-0 corrections from atmospheric
transmissivity and rain volume backscatter Flag pixels that correspond to high rain
attenuation
QRad Algorithm Block Diagram
Bin Slice Sig-0
SpiralWind Direction
Atmos. Attenand
BackscatterCorrection
L2A Tb’s
Hurricane Wind Speed
QScatL1B sig-0
Locate Center
QRadRain Rate
RetrieveWind Speed
Hurricane Wind Retrieval
Hurricane Eye Location
Based uponAverage of “4-flavor”Sigma-0’s12.5 kmsampling
Longitude
Lat
itude
QRad/SRad Rain Algorithm
Look at noise channel of scatterometerSubtract echo channelCalibrate radiometric temperature vs. TMI
Train brightness temperature/rain rate relationship via TMI
Coincident with scatterometer measurement
QRad Integ. Rain Rate Product
Improved CFRSL rain retrieval algorithm provides earth-gridded 50 km data product
Instantaneous integrated rain rates > 2.4 km*mm/hr
Resampled to 12.5 km wind vector grid
QRad – TRMM 2A12 Instantaneous Rain Rate
QRad TMI
Longitude
Lat
itu
de
Land
QRad – TRMM 3B42RT HQ Instantaneous Collocated Low Rain event
QRadTMI
QRad – TRMM 3B42RT HQ Instantaneous Collocated Moderate Rain event
QRadTMI
QRad – TRMM 3B42RT HQ Instantaneous Collocated High Rain Event
QRadTMI
QRad (CFRSL) & TMI Integrated Rain Rates for Simultaneous Events
TMI Integ. Rain Rate, km*mm/hr
CF
RS
L I
nteg
. Rai
n R
ate,
km
*mm
/hr
AMSR vs. SRad Path Attenuation, Horizontal Polarization
102
AMSR Attenuation SRad Attenuation
2003 Hurricane Results
HRD Wind Field, Time Interpolated CFRSL Wind Retrieval
QRad Rain Rate(mm/hr)
QuikSCAT Rev. 22055, Sept 13, 2003 22:04 Z
(m/sec)
SSMI Rain Rate
HRD Wind Field, Time Interpolated(m/sec)
SeaWinds Rev. 03927, Sept 15, 2003 15:40 Z
SRad Rain Rate(mm/hr)
CFRSL Wind Retrieval
SSMI Rain Rate
CFRSL Wind Retrieval
SRad Rain Rate(mm/hr)
HRD Wind Field, Time Interpolated(m/sec)
QuikSCAT Rev. 22084, Sept 15, 2003 22:52 Z
SSMI Rain Rate
HRD Wind Field 01:30 Z
SeaWinds Rev. 03934, Sept 16, 2003 02:52 Z
CFRSL Wind Retrieval
SRad Rain Rate(mm/hr)
(m/sec)
SSMI Rain Rate
HRD Modeled Wind Speed (m/s)
CF
RS
L W
ind
Spe
ed (
m/s
)
HRD Modeled Wind Speed (m/s)
JPL
Win
d S
peed
(m
/s)
SeaWinds Rev. 03934, Sept 16, 2003 02:52 Z
JPL Wind Field CFRSL Wind Retrieval
QuikSCAT vs. H* Wind Analysis
SeaWinds vs. HRD Model
CFRSL AlgorithmComposite Wind Speeds
Conclusion Ready to test current algorithm in operational
environment Acceptable estimates of high rain rates inside
storm conditions Reasonable wind speed retrievals up to 40 - 45 m/s
Work must be done to improve model function and rain backscatter and attenuation estimates Will utilize UMass IWRAP and SFMR data set Have simultaneous AMSR and SRad for the 2003
hurricane season