1

Status and Future of GPCP and TRMMStatus and Future of GPCP and TRMMRobert Adler

Laboratory for Atmospheres/NASA Goddard

2

Tropical Rainfall Measuring Mission (TRMM)Tropical Rainfall Measuring Mission (TRMM)• NASA/JAXAJoint missionNASA/JAXAJoint mission launched in launched in

Nov. 1997 into inclined (35º) orbit; Nov. 1997 into inclined (35º) orbit; spacecraft and instruments in excellent spacecraft and instruments in excellent conditioncondition

• Program: Program: NASA’s Precipitation NASA’s Precipitation Measurement Missions (PMM); PMM Measurement Missions (PMM); PMM science team covers TRMM and GPMscience team covers TRMM and GPM

• Instrument Payload: Instrument Payload: – TRMM Microwave Imager (TMI)

• 10, 19, 37, 86 GHz, conical scanning

– Precipitation Radar (PR) [Japan]

• 14 GHz, cross-track scanning

– Lightning Imaging Sensor (LIS) [MSFC]

• Staring optical array

– Visible IR Scanner (VIRS)

• 5-channel, cross-track scanning

– Cloud & Radiant Energy System (CERES) [LRC]

• Radiation budget (failed after 6 mos.)

• Science Objective: Advance knowledge of global water and energy cycles through observed time and space distributions of tropical rainfall, hydrometeor structure and latent heating.

• Approach: Accurate estimation of precipitation characteristics through first-time use of passive and active microwave instruments.

3

First TRMM Science Workshop--1986

First Report--19881986-2006: Twenty years of TRMM!

4

Major Science Results

• Space standard for measuring precipitation• Improved climatology of tropical rainfall and

variations• Convection intensity observations and variations• Climatology of lightning over land and ocean• Vertical heating structure and diurnal variations• Improved climate and weather modeling • Impact of humans on precipitation • Hurricane/typhoon structure/evolution • Multi-satellite (~3-hr) rainfall analyses using

TRMM+other satellites • Flood and agricultural applications • Operational use of data by weather agencies.

Senior Review Proposal

Tropical Rainfall Measuring Mission (TRMM)Tropical Rainfall Measuring Mission (TRMM)

5

Tropical Rainfall Measuring Mission Tropical Rainfall Measuring Mission (TRMM)(TRMM)

Eight-Year TRMM Eight-Year TRMM ClimatologyClimatologyJanuary 1998 - December 2005January 1998 - December 2005

TRMM Multi-satellite product (TMPA--3B43)

6

TRMM reduces uncertainties in tropical ocean rainfall to ~5%

7

Diurnal Cycle of TRMM Precipitation FeaturesDiurnal Cycle of TRMM Precipitation FeaturesComprehensive Global Census of Rain Events RevealsComprehensive Global Census of Rain Events Reveals

Different Timing, Character of Rain Maxima Over Land vs. WaterDifferent Timing, Character of Rain Maxima Over Land vs. Water

1.1. Rain max from features over the ocean is due only to an increase in their Rain max from features over the ocean is due only to an increase in their number in the early morning.number in the early morning.

2. The broad overnight continental MCS rainfall max results from decreasing 2. The broad overnight continental MCS rainfall max results from decreasing numbers and increasing areas.numbers and increasing areas.

3. Continental features peak in number and conditional rain rate during the 3. Continental features peak in number and conditional rain rate during the afternoon: this dominates the higher amplitude diurnal cycle over afternoon: this dominates the higher amplitude diurnal cycle over land.land.

Oceans Continents

Tropical Rainfall Measuring Mission (TRMM)Tropical Rainfall Measuring Mission (TRMM)

Zipser

8

TRMM - Derived 3D Latent Heating DistributionTRMM - Derived 3D Latent Heating Distribution

Latent heating in convectiveand stratiform clouds drivesthe tropical Hadley Cell - playscrucial role in poleward heattransport by Earth’s atmosphericand oceanic fluid system.

A primary mission objective ofTRMM is to quantify the 4D distribution of tropical latentheat release.

Accurate estimates of heatingare crucial for climate modelsand their cumulusparameterization schemes.

Areas of largest rain rates mapto the greatest in-cloud heating.

Annual average latent heatingis maximized across the Pacific,over the Maritime Continent,and is largest at high altitudes(~ 8 km).

TaoTao

9

Impact of Humans on PrecipitationImpact of Humans on PrecipitationImpact of Cities on Impact of Cities on

RainfallRainfall

Houston downwind rainfall maximum (Shepherd)

1

23

Effect of Pollution on Effect of Pollution on Rainfall Over OceanRainfall Over Ocean

Lack of PR-detected rain in polluted clouds (Rosenfeld)

0

0.1

0.2

0.3

Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri

Summer (JJA) Rain Rate vs. Day of Week

Mean Rain Rate (mm/h)

Coastal Atlantic(Area C)

Southwest U.S.(Area A)

Southeast U.S.(Area B)

(a)

Pollution Impact on Pollution Impact on Land RainfallLand Rainfall Increase in Summer Rain over SE U.S. during week (red curve)--Increase offshore on weekend (blue curve)--(Bell)

10

TRMM Data Used for Hurricane/Typhoon MonitoringTRMM TMI data used by NOAA and DoD

(and int’l agencies) for tropical cyclone detection, location and intensity estimation--600 TRMM-

based tropical cyclone “fixes” in 2004

TRMM orbit advantageous for tropical cyclone monitoring--

despite narrow swath it is always in tropics, sampling about same as

one SSM/I over all tropics, but TRMM sampling best in 10-35º

latitude storm band. TMI resolution twice as good as SSM/I,

about same as AMSR. Precessing orbit provides off-time

observations relative to sun-synchronous microwave observations.

TRMM image from NRL Tropical Cyclone web site

Hurricane Katrina

TRMM radar (PR) cross-sections of hurricanes available in real-time for operational analysis from TRMM web site--potential for PR use not realized at this point--data readily available

from TRMM web site

11

Combined “high quality” (conical scanning) microwave data coverage: Averages 55% with TRMM, AMSR-E and 3 SSM/I’s

Addition of 3 AMSU-B’s (lower quality over ocean): Total coverage averages ~ 85%

TRMM Calibrating Other Satellites in TRMM Multi-TRMM Calibrating Other Satellites in TRMM Multi-satellite Precipitation Analysis (TMPA) (3 hr)satellite Precipitation Analysis (TMPA) (3 hr)

TRMM Calibrating Other Satellites in TRMM Multi-TRMM Calibrating Other Satellites in TRMM Multi-satellite Precipitation Analysis (TMPA) (3 hr)satellite Precipitation Analysis (TMPA) (3 hr)

Remaining gaps filled by Geo-IR precipitation estimates Version 6 3B42: Eight year,

3-hr data set

12

Largest Daily Rainfall Over 8-Largest Daily Rainfall Over 8-year Periodyear Period

Use TMPA for Analysis of Extreme Precipitation Events

13

Science with an Extended TRMM Mission (2006-2012?) Science with an Extended TRMM Mission (2006-2012?) (from Senior Review proposal)(from Senior Review proposal)

• An improved climatology of precipitation characteristics, especially extremes

• Improved diagnosis and closure of global (and regional) water cycles

• Diagnosis and testing of inter-decadal and trend-related processes in the water cycle

• Assessment of impact of humans (e.g., cities and aerosols) on rainfall characteristics and processes

• Robust determination of convective system, tropical cyclone and lightning characteristics

• Advances in hydrological applications over land on basin and continental scales

• Improved modeling of global water/energy cycles for weather/climate predictions

• Improved monitoring and forecasting of tropical cyclones, floods and other hazardous weather

Unique opportunity to obtain combined active and passive observations of clouds, aerosols, and

precipitation with “A-Train”--Cloudsat, CALIPSO, Aqua--and TRMM

14

TRMM--Past, Present, FutureTRMM--Past, Present, Future• TRMM Experimental Phase (Jan. 1998-August 2001[~3.5 years]).

350 km altitude. (better PR sensitivity)• TRMM Extended Phase (August 2001-present). 402 km altitude.

(reduced PR sensitivity[5+ years]). Fuel sufficient to ~2012• Version 6 TRMM products improved, but impact of boost evident;

Version 7 (~2008) will address boost issue and transition toward GPM era

• TRMM (with radar and passive microwave in inclined orbit) is now key to calibrating polar orbiting passive microwave satellites (currently Aqua/AMSR, 3 DMSP/SSM/I’s, 3 NOAA/AMSU’s) and GeoIR satellites, allowing for development of high time resolution precipitation information.

• TRMM extension decision allows for continuation of TRMM-based science and applications, up to and (hopefully) overlapping GPM core (also at ~400 km altitude).

• GPM will add critical microphysical information, expand latitude range to middle and high latitudes, provide improved microwave sampling, and lengthen important radar/radiometer record started by TRMM.

15

Global Precipitation Climatology Project Global Precipitation Climatology Project (GPCP)(GPCP)

A GEWEX Global Data Project under World Climate Research A GEWEX Global Data Project under World Climate Research Program (WCRP)Program (WCRP)

http://lwf.ncdc.noaa.gov/oa/wmo/wdcamet-ncdc.htmlhttp://precip.gsfc.nasa.gov

16

GPCP Objectives• Development and production of long-term, global precipitation analyses at monthly and finer time scales for use in studies of weather and climate variations

• Evaluation and characterization of quality of estimates for various applications

• Improving the analyses through incorporation of new data, improved analysis techniques, etc.

• Analysis of the data sets--precipitation alone or in combination with other components of the hydrological cycle

17

produced ~ 3 months after observation time

[although produced using different data sets and algorithms, products are

integrated,i.e. they add up]

GPCP Global Precipitation Products

NASA, NOAA, DWD, Universities, JMA, EUMETSAT• Monthly, 2.5° Merged Analysis (1979-present) Adler et al. (2003), J. Hydromet.

• Pentad, 2.5° Merged Analysis (1979-present) Xie et al. (2003) J. Climate

• Daily, 1° Merged Analysis (1997-present) Huffman et al. (2001) J. Hydromet.

“GPCP” in title or abstract of 58 journal papers; product reference papers cited over 500

times

18

GPCP Components/People• Merge Center--Adler/Huffman, NASA Goddard• Gauge Center--Fuchs/Schneider, German Weather Service, Global Precipitation Climatology Center (GPCC)

• Microwave-Land Center--Ferraro, NOAA NESDIS• Microwave-Ocean Center--Chiu, George Mason U./NASA Goddard• Geosynchronous Center--Janowiak/Xie, NOAA/NWS/CPC (also do pentad merge and supplemental gauge input)

• Additional satellite data and data processing provided by JMA and EUMETSAT GPCP Assessment--Gruber/Levizzani

19

Variations in Global Precipitation (1979-2005)

Little or no linear change during period--ocean and land precipitation tend to compensate

Pattern of Linear change (1979-2005)

20

Tropical Rainfall Variations (ENSO, volcanoes, long-term change)

Original Monthly Series

Derived ENSO ocean and land signals

Derived volcano impact-up to 5%

Derived data set with ENSO and volcanic signals “removed”-note reduced amplitude of variations

Figure from Gu et al. (2006)

21

Time Series of Annual Totals (Tropics)

2005-largest annual tropical rainfall in series

Linear positive change 5% over ocean and 3% over ocean/land combined--statistically significant at ≥ 99%. May indicate long-term precipitation change signal. Additional analysis is ongoing.

Figure from Gu et al. (2006)

22

Issues with Current Products• Current merge approach and bias

errors in gauge analysis in mountains leads to underestimation in these areas--noted by hydrologists

• Currently TRMM, AMSR and AMSU data not included

• Data boundaries at1986 (gauge analysis shift, geosynchronous data start) and July 1987 (OLR/OPI-geo to SSM/I shift)

23

These changes would be incorporated in a Version 2.1 and will be one focus at working group meeting in Nov.

Product Plans (Short-term [2006-2007])

• Possible use of new GPCC (German Weather Service) 50-year gauge analysis as base gauge analysis (would eliminate gauge data boundary at 1986)

• Possible “quick-look” monthly product shortly after end of month for use in climate monitoring

• Possible ororaphy adjustment as a function of altitude/climate regime

24

GPCP Product Plans (Version 3/Reprocessing)

Possible Improvements in new analyses:• Coordinated analysis methods and input data sets across

time resolutions and record length (1979--present)• Minimization of data set time boundaries, (or other)

boundaries• Higher time and space resolutions (~ 3 hr, 25 km) for

part of the period (e.g., 1998-present)--possible community approach

• New passive microwave algorithm (s), new passive microwave data (AMSR, TRMM, AMSU); use of TRMM radar for calibration; use of daily gauges

• Integration of high time/space resolution period with longer period with coarser time/space resolution

• Rain/snow discrimination (probably by temperature)• Goal is to have Version 3/Re-processing plan early in

2007 that results in community processing effort

25

Back-up Slides

26

TRMM BAMS articleSimpson, Adler and North (1988)

March 1988--9 years before launch!