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 ProcessingA 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]

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 1.21De

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Jul

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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:

george.j.huffman@nasa.gov

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