upgrades to the real-time tmpa g.j. huffman 1,2, d.t. bolvin 1,2, ej. nelkin 1,2, r.f. adler 3, e.f....
TRANSCRIPT
Upgrades to the Real-Time TMPAG.J. Huffman1,2, D.T. Bolvin1,2, EJ. Nelkin1,2, R.F. Adler3, E.F. Stocker1
1: NASA/GSFC Earth Sciences Division2: Science Systems and Applications, Inc.3: Univ. of Maryland College Park/ESSIC
http://precip.gsfc.nasa.gov
1. TMPA SYSTEM - Data Sources and Processing
A diverse, changing, uncoordinated set of input precip estimates, with various• periods of record• regions of coverage• sensor-specific strengths, limitations
Seek the longest, most detailed record of “global“ precip
Combine the input estimates into a “best” data set
Run twice:• (near-)real time (~8 hr after observation time)• research quality (~2 months later, after “all” data are received)• the focus here is the real-time
3. RT FEATURES THAT REMAIN THE SAME
Computed on coincident 3-hr, 0.25° data in the band 50°N-S for uncalibrated (RT(U)) and calibrated 3B42RT (RT(C)) against the production Version 6 3B42 (P)
Lacking Version 7, we show the performance for Version 6, which should be similar
Better values are colored in green
Bias• mixed results• global values are just a small residue of larger regional differences• worse global-average bias could result from improvement mainly in regions of one sign
RMS• calibrated version almost always better• implies improvement in most regions
Boreal cold season (Jan 2007, Dec 2008)• calibrated land is marginally worse for both Bias and RMS• most land is in the Northern Hemisphere – believed to reflect relatively large cold-season errors
The new Version 7 Real-Time TMPA is being readied for release• approx. calibrated to the Version 7 production post-real-time TMPA• includes upgrades to most input data sets• includes SSMIS input data for the first time• provides retrospectively processed data starting in Feb. 2000
The expected release date for RT is late Spring 2012• the pacing item is completing computation of climatological calibrations to the Version 7 calibrators• thereafter, both retrospective processing and processing for new data can begin• Version 6 RT processing will continue during the switch-over
4. FINAL REMARKS
Native binary • trmmopen.gsfc.nasa.gov• 3B40RT: microwave precipitation, error, pixel counts, source• 3B41RT: IR precipitation, error, pixel counts• 3B42RT: combined microwave/IR precipitation (both original and calibrated to 3B42), error, source
KMZ (for Google Earth)• trmmopen.gsfc.nasa.gov• 3B42RT: combined microwave/IR precipitation(calibrated to 3B42)
Flat binary• through TOVAS• 3B42RT: combined microwave/IR precipitation (calibrated to 3B42)
Text• through TOVAS• 3B42RT: combined microwave/IR precipitation (calibrated to 3B42)
TOVAS on-line visualization• 3B40RT: microwave precipitation• 3B41RT: IR precipitation• 3B42RT: combined microwave/IR precipitation (calibrated to 3B42)
A Note on TerminologyGeneral approach: TRMM Multi-satellite Precipitation Analysis [TMPA]Real-time product: 3B42RT [RT], providing two precipitation fields• original multi-satellite, without climatological calibration [RT(U)]• multi-satellite with climatological calibration, [RT(C)]Version 7 post-real-time production product: 3B42 [P]
A Note on TerminologyGeneral approach: TRMM Multi-satellite Precipitation Analysis [TMPA]Real-time product: 3B42RT [RT], providing two precipitation fields• original multi-satellite, without climatological calibration [RT(U)]• multi-satellite with climatological calibration, [RT(C)]Version 7 post-real-time production product: 3B42 [P]
Instant-aneous
SSM/ITRMMAMSRAMSU
HQ coefficients
3-hourly merged HQ
3-hourly IR Tb
Hourly HQ-calib IR precip
3-hourly multi-satellite (MS)
Monthly
gauges Monthly SG
Rescale 3-hourly MS to monthly SG
Rescaled 3-hourly MS
Calibrate High-Quality (HQ) Estimates to
“Best”
Merge HQ Estimates
Match IR and HQ, generate coeffs
Apply IR coefficients
Merge IR and HQ estimates
Compute monthly satellite-gauge combination (SG)
30-day IR coefficients
Monthly
Climo.
Adj. Coeff.
Processing Sequence
Both RT and P computed on a 3-hr 0.25° grid
Microwave precip:• intercalibrate, combine
IR precip:• calibrate with microwave
Combined microwave/IR:• IR fills gaps in microwave
Both RT and P calibrate the initial 3-hr MS• RT does monthly climatological calibration on 1° grid• TMI-TCI calibration first, then gauge• uses 10 years of match-ups, broken into monthly fields
Both RT and P will archive both uncal. and cal. 3-hr MS
Upgrades and Reprocessing
Episodically, the TMPA is upgraded to take advantage of• new/revised input data• improved processing concepts
Ideally, upgrades are accompanied by reprocessing to ensure consistency of the entire data set• built in to P system• new concept for RT – this is the first time
Bias (mm/d) RMS (mm/d)RT(U)-P RT(C)-P RT(U)-P RT(C)-P
Land 0.203 0.511 2.09 2.41Ocean 0.020 0.016 1.04 0.88All 0.069 0.147 1.40 1.45Land 0.603 0.467 2.16 1.86Ocean 0.046 0.073 1.00 0.90All 0.194 0.178 1.41 1.23Land 0.399 0.535 2.31 1.90Ocean -0.079 0.053 1.04 0.98All 0.048 0.181 1.49 1.29Land 0.650 0.439 2.17 1.79Ocean 0.057 0.100 0.93 0.92All 0.214 0.190 1.37 1.21Land 0.162 -0.012 1.60 1.56Ocean -0.012 -0.042 0.90 0.80All 0.034 -0.034 1.13 1.05Land -0.364 -0.315 1.78 1.66Ocean -0.007 0.0 0.99 0.87All -0.101 -0.083 1.25 1.13Land -0.194 -0.605 1.66 1.86Ocean 0.042 0.035 0.94 0.86All -0.020 -0.134 1.17 1.21D
ec’08 Nov’08 Oct’08 Oct’07 Jul’07
Apr’07 Jan’07
V7 vs. V6 P – July 2008
2. RT ENHANCEMENTS FOR VERSION 7
2000 2004
TMI
2002
SSM/I F14
SSM/I F13
SSM/I F15
AMSU N16
AMSU N15
AMSU N17
AMSR-E
CPC Merged IR
2006
SSMIS F16
MHS N18
MHS N19
SSMIS F17
2008 2010
MHS MetOp
SSMIS F18
2012
2000 2004
Original RT
2002
Retrospective Version 7 RT
2006 2008 2010 2012
Users requested this to provide• an extended data record• with consistent processing• for quantitative work (hydrology, crop forecasting)
Most existing input data sets are upgraded
Additional periods of record are included (boxes)• some parts of the data records are not suitable – shown with lighter-color lines
SSMIS is used for the first time
Dotted vertical line indicates start of CPC Merged IR dataset• the P before this time depends on a different IR data set not considered in the RTThe previous RT record was inhomogeneous in time• black hash marks denote substantial
changes in input data types, input data algorithms, or RT processing• the only fully consistent record was October 2008 – present• without reprocessing, the changes listed above would have implied starting over with a new, different data series when Version 7 RT starts (in 2012)
Retrospective processing provides a uniformly processed 12-year record• P is still the dataset of choice for research – the goal here is to facilitate calibration of real-time
applications
There are still caveats:• changes in the satellite constellation still create potential inhomogeneities• the retrospective processing for RT will be run on the P input data, introducing the possibility of
small differences compared to running in real time on the RT input data
Lacking Version 7 RT, we compare an example month of Versions 6 and 7 P, which should be similar to comparing Versions 6 and 7 RT
Comparing Version 6 to Version 7 P for July 2008 (general product name is 3B43)• this is the first sample month• Version 7 tends to be somewhat higher over ocean• the Southern Ocean is lower, perhaps due to seasonal effects?• changes over land should be driven by differences in the gauge analysis• Version 6 gauge for this month is CAMS; Version 7 gauge is GPCC throughout• dramatic changes in the Indian Monsoon area are likely due to data gaps in CAMS• Version 7 values are considered better
V7 3B43 Jul 2008 (mm/d)
V6 3B43 Jul 2008 (mm/d)
(V7) – (V6) Jul 2008 (mm/d)
Comparing Version 6 and Version 7 P to atoll gauge data for July 2008• atoll data from the PACRAIN archive at Univ. of Oklahoma• the western tropical Pacific yielded 8 atolls, each corresponding to a 0.25°x0.25° grid box of P data• the average biases are:
• Version 6: -1.60 mm/d (-20%)• Version 7: -0.56 mm/d (-7%)• consistent with maps above
RT Format Remains the Same RT Is Again Climatologically Calibrated to P
Version 7 RT Will Include Retrospective Processing Upgraded Input Data Should Yield a Better Product in Version 7
Questions or to to be put on the notification e-mail list:
Web pages: http://precip.gsfc.nasa.govhttp://trmm.gsfc.nasa.gov
3B42/43 document: ftp://meso.gsfc.nasa.gov/pub/trmmdocs/3B42_3B43_doc.pdf
3B4xRT documents:ftp://meso.gsfc.nasa.gov/pub/trmmdocs/rt/
Poster PT-2