Precipitation Precipitation Retrievals Over Land Retrievals Over Land Using SSMIS Using SSMIS Nai-Yu Wang Nai-Yu Wang 1 and Ralph R. and Ralph R. Ferraro Ferraro 2 1 1 University of Maryland/ESSIC/CICS University of Maryland/ESSIC/CICS 2 2 NOAA/NESDIS/STAR NOAA/NESDIS/STAR
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Precipitation Retrievals Over Land Using SSMIS Nai-Yu Wang 1 and Ralph R. Ferraro 2 1 University of Maryland/ESSIC/CICS 2 NOAA/NESDIS/STAR.
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Precipitation Retrievals Precipitation Retrievals Over Land Using SSMIS Over Land Using SSMIS
Nai-Yu WangNai-Yu Wang11 and Ralph R. Ferraro and Ralph R. Ferraro22
1 1 University of Maryland/ESSIC/CICSUniversity of Maryland/ESSIC/CICS2 2 NOAA/NESDIS/STARNOAA/NESDIS/STAR
OutlineOutline
MotivationMotivation Current status of GPROF land Current status of GPROF land Profiling approachProfiling approach High frequency and temperature High frequency and temperature
sounding channels from SSMIS sounding channels from SSMIS Land precipitation retrievals in Land precipitation retrievals in
complex terrain complex terrain Conclusions and future work Conclusions and future work
MotivationMotivation
Improve current precipitation retrievals over Improve current precipitation retrievals over land (TMI GPROF 6.5 land) land (TMI GPROF 6.5 land)
Explore mid-latitude precipitation retrieval Explore mid-latitude precipitation retrieval using passive microwave radiometer high using passive microwave radiometer high frequency and sounding channels, in frequency and sounding channels, in preparations for GPM preparations for GPM High frequency bands between 150 and 183 GHzHigh frequency bands between 150 and 183 GHz
Less sensitive to surface emissivity variationsLess sensitive to surface emissivity variations Respond to thick clouds, water vapor, and precipitationRespond to thick clouds, water vapor, and precipitation
Oxygen absorption bands between 50 and 60 GHzOxygen absorption bands between 50 and 60 GHz Primarily probe atmospheric temperature and moisture Primarily probe atmospheric temperature and moisture
profiles, might be critical in classifying different climate profiles, might be critical in classifying different climate regimes (e.g., freezing height) regimes (e.g., freezing height)
Current status of GPROF Current status of GPROF LandLand
TMI GPROF 6.5 landTMI GPROF 6.5 land Ferraro’s scattering index (SI) and Ferraro’s scattering index (SI) and
rainrate algorithm for SSMI and TMI, rainrate algorithm for SSMI and TMI, utilize 22 and 85 GHzutilize 22 and 85 GHz
TRMM TMI SI and PR rainrate matchups, TRMM TMI SI and PR rainrate matchups, convective probability, separate convective probability, separate convective and stratiform in the convective and stratiform in the database; coastline improvements database; coastline improvements (McCollum and Ferraro)(McCollum and Ferraro)
coupling CRM outputs with radiative coupling CRM outputs with radiative transfer calculations to construct an a transfer calculations to construct an a priori database of brightness temperatures priori database of brightness temperatures and the hydrometeor profiles over land and the hydrometeor profiles over land
Profiling ApproachProfiling Approach
Use a probabilistic approach to calculate the most likely a Use a probabilistic approach to calculate the most likely a posteriori distribution constrained by actual satellite posteriori distribution constrained by actual satellite measured brightness temperatures measured brightness temperatures
Precipitation estimates are weighted averages of the mean Precipitation estimates are weighted averages of the mean precipitation values corresponding to the classes in the precipitation values corresponding to the classes in the databasedatabase
GPROF land profiles are selected exclusively fromGPROF land profiles are selected exclusively from GPROF CRM simulations that are predominantly GPROF CRM simulations that are predominantly
from tropical oceanic systems from tropical oceanic systems Profiles tested:Profiles tested:
GCE TRMM LBA: simulations of mesoscale convective GCE TRMM LBA: simulations of mesoscale convective system during Jan-Feb in Brazilsystem during Jan-Feb in Brazil
MM5 MIDACF: mid-Atlantic ocean cold front systemMM5 MIDACF: mid-Atlantic ocean cold front system 5 classes of hydrometeor: cloud water, cloud ice, rain, 5 classes of hydrometeor: cloud water, cloud ice, rain,
ice and graupelice and graupel 1-1.5 km horizontal resolution, averaged to individual 1-1.5 km horizontal resolution, averaged to individual
SSMIS resolutions (15 km for 150, 183 GHz)SSMIS resolutions (15 km for 150, 183 GHz) Radiative transfer model: Eddington two-stream Radiative transfer model: Eddington two-stream
approximation (Kummerow)approximation (Kummerow)
Land database issuesLand database issues Bayesian approachBayesian approach
Strength : direct use Strength : direct use of explicit microphysical of explicit microphysical mechanisms in CRMmechanisms in CRM Disadvantage: Disadvantage: susceptible to errors susceptible to errors in the a priori databasein the a priori databasein terms of the accuracyin terms of the accuracyof microphysical details, of microphysical details, and the fidelity with whichand the fidelity with whichthe model outputs capturethe model outputs capturedifferences in climate differences in climate regimes. An example. regimes. An example.
Observations: SSMISObservations: SSMIS
Conical scanned passive Conical scanned passive microwave radiometer, microwave radiometer, launched in Oct 2003launched in Oct 2003
Grid all channels to 0.15 deg Grid all channels to 0.15 deg
in latitude/longitude gridsin latitude/longitude grids
Courtesy of Dr. Joe Turk
NOAA HMT 2006 siteNOAA HMT 2006 site
Complex terrainComplex terrain Off coast of CaliforniaOff coast of California American river basinAmerican river basin Sierra mountainSierra mountain Winter time floodingWinter time flooding
IOP4 : DEC 30-31, 2005IOP4 : DEC 30-31, 2005Cold frontal system, moist oceanic Cold frontal system, moist oceanic air mass crossed the area, air mass crossed the area, small scale rain band structure, small scale rain band structure, high snow level on the groundhigh snow level on the ground
High Frequency Precipitation signalsHigh Frequency Precipitation signals
SSMIS Dec 31, 2005 1637ZSSMIS Dec 31, 2005 1637Z
Surface ScreeningSurface Screening Surface ice and snow, Surface ice and snow, and sand yield similarand sand yield similarscattering signatures as scattering signatures as precipitationprecipitation Screening surface scatters Screening surface scatters
““scattering index” SI to locatescattering index” SI to locatehigh scattershigh scatters combinations of low/highcombinations of low/high
frequency channels to differentiatefrequency channels to differentiate
Preliminary Rain RetrievalPreliminary Rain RetrievalDecember 31, 2005 December 31, 2005
SSMIS retrieved rainratesfrom 50, 150, 183+-1/+-7 GHz at 1637Z
Composite radar reflectivity at 1700Z
Conclusions and Future Conclusions and Future WorkWork
A framework of land precipitation profiling retrieval A framework of land precipitation profiling retrieval algorithm using passive microwave high frequency is algorithm using passive microwave high frequency is establishedestablished
Currently, retrieval does not have the ability to locate the Currently, retrieval does not have the ability to locate the freezing level and differentiate convective and stratiform freezing level and differentiate convective and stratiform systems from brightness temperaturessystems from brightness temperatures plan to gather large number of matchups between plan to gather large number of matchups between
SSMIS, TRMM PR and CloudSat for different climate SSMIS, TRMM PR and CloudSat for different climate regimes to enhance the retrieval skillregimes to enhance the retrieval skill
Radar reflectivity/hydrometeor profiles will also used to Radar reflectivity/hydrometeor profiles will also used to build up hydrometeor database for landbuild up hydrometeor database for land
Validate radiative transfer model with HMT ground radars Validate radiative transfer model with HMT ground radars and satellite radar matchups and satellite radar matchups