global precipitation— gpcp, trmm and gpmipwg/meetings/bologna-2016/bologna2016_orals/8-1... ·...
TRANSCRIPT
GlobalPrecipitation—GPCP,TRMMandGPM
MeansandVariations
RobertAdler,Jian-Jian Wang,Guojun Gu,MattSapianoUniversityofMaryland
GeorgeHuffman,DaveBolvin,EricNelkinNASA/Goddard
Udo SchneiderGPCC/DWDRalphFerraro,Ping-PingXie NOAA
andothers
1
Global Precipitation Climatology Project (GPCP)Climatology(1979-2015)
GPCPisanoften-usedanalysis basedonsatelliteandgaugedata(1979-nearpresent).NoTRMM,GPMorCloudsat dataareinthecurrentGPCP.
mm/d
Adleretal.,2003J.HydrometHuffmanetal.,2009GRL
2
WebAddressforCurrentGPCPproducts:GPCP.umd.edu
� New GPCPMonthly(V2.3)beingproducedatUMDforNOAA’sClimateDataRecord(CDR) program
� Final analysisavailableafewmonthsaftertime;Interim CDR(ICDR)available~10daysafterendofmonthforreal-timeclimateanalysis
� V2.3Daily andPentad productsunderdevelopment
3
GPCPNewV2.3vs.V2.2
�Differencesduetocross-calibrationerrors(SSMItoSSMISandTOVStoAIRS)overoceananduseofnewGPCC“Full”gaugeanalysis
� Biggestdifferenceafter2009(~1.8%overocean)� Regionallybiggestdifference40-60Noverocean
Land+Ocean
Land
Ocean
4
CurrentGPCPgloballong-termnumberis2.69mm/d +/- ~7%Withtheerrorbasedonvariationsamongdifferentestimates(includingTRMM)
(Adleretal.2012JAMC)
Theseglobalnumbersandcontinental-scalevaluesfitwellwithlarge-scalewaterandenergybudgetstudies(e.g.,Rodell etal.2015J.Clim.)
But,howwelldotheseverylarge-scaleprecipitationnumberscomparewithTRMM,GPMandCloudSat?
AbsoluteMagnitudeofGlobal PrecipitationOcean Land Ocean+Land
Precipitation 2.90 mm/d 2.24 mm/d 2.69 mm/d *
*NewvaluesbasedonGPCPV2.3
5
**Behrangi etal.,2014JClim
Tropical Mean(Ocean) RainfallEstimates
TRMM-based mean tropical oceanvalues agree well with GPCP and withTRMM PR/CloudSat value.
*Adleretal.2009JMSJ
HowdoTRMM-basedestimatesfitwithGPCP?
6
GPCPPR+ CloudSat;AMSR+ CloudSat
60N-60S(ocean)
3.04mm/d
3.13[GPCP+~3%]
Behrangi etal.2014JClim
Global Mean(Ocean) RainfallEstimates
GPCPglobaloceannumberstillseemsreasonable.IftherearefaultsintheGPCPglobalprecipitationmagnitude(e.g.,underestimation)it
probablydoesn’thavetodowithlightrainorsnow,butperhapswithintenseconvectiverainfallinthetropics.
7
� GPM somewhat higher than GPCPin tropics
� GPM lower in extra-tropics
Ocean
Version4ofGPMProducts
GPMTwo-YearPrecipitationfromPassiveMicrowave(GMI)andRadar(DPR)GPM
GPMCompositeMarch2014– Feb.2016
OceanZonalMean(March2014-Feb.2016)
GPCP
Equator
45° N
45° SGPCPArtifact
GPM
mm/d PMW Radar Comb GPCP25N-25S 3.50 3.63 3.37 3.3365N-65S 2.70 2.83 2.63 3.07
GPCPMarch2014– Feb.2016
8
OceanZonalMean(March2014-Feb.2016)
GPCP
Equator
45° N
45° S
GPM
80N
80S
XXMeanValues(55-80NOcean)CloudSat GPCP
CloudSat GPCP
MeanValues(55-80NOcean)
XX
CloudSat HighLatitudeStudy
Behrangi etal,(2016)JGRMeanvaluesofprecipitation(rainplussnow)overfiveyears,55-80° latitude:
CloudSat-basedestimatesagreecloselywithGPCPmeans(overoceanandland);bothhigherthanGPM
GPMandCloudSat shouldbetheStandardstowhichGPCPistuned!
9
VariationsinGlobal SurfaceTemperatureandPrecipitationTrends,Inter-decadalShiftsandENSOandVolcanoEffects
SurfaceTemperature:Trend:.15C/decadeENSO:0.2CamplitudeVolcano:0.4Camplitude
Precipitation:Trend:~zeroENSO:.05mm/d(2%)amplitude
9%/KVolcano:.09mm/d(3%)amplitude
8%/K
ClimateShift
GlobalSurfaceTemperature
GlobalPrecipitation(GPCP)
10
WaterVapor Precipitation(GPCP)
Trends 10%/C(ocean) ~ 1 %/C(global)
Inter-annualENSO
15%/C(ocean) 9%/C(global)
Inter-annualVolcano
9%/C(ocean) 8%/C(global)
ComparisonofWaterVaporandPrecipitationChangesinRelationtoTemperatureChangesforInter-annualandTrendTimeScales
Precipitationvariationsvarydifferentlyfromwatervaporontrendscale,butaremuchmoresimilarforinter-annualscale—
forbothENSOandvolcanoes11
TRMM-based Sfc.Temp.-RainfallRelations(Activevs.PassiveMicrowave)1998-1999ElNinotoLaNinaTransition
RainfallAnomaly
(%)
SurfaceTemperatureAnomaly(°)
TRMMPassiveMicrowaveGPCPPassiveMicrowave
TRMMRadarNS,2km,4km
TRMMRadar6km
TRMMCombined
TRMMRadardoesnotconfirmPMWT-Rrelations—Attenuationissues?
Ocean
TRMM
12
SurfaceTemperatureAnomaly(C)
RainfallAnomaly
(%)
GPM-based Sfc.Temp.-RainfallRelations(Activevs.PassiveMicrowave)2014-2016NeutraltoElNinoTransition
GPMPassiveMicrowave
GPCPPassiveMicrowaveGPMRadarNS,2km,4km
GPMCombined
GPMRadarbetterconfirmsPMWT-Rrelations—notclearwhydifferentfromTRMM?
GPMRadar6km
GPMRadar~13%/CTRMMRadar~0%/C
Ocean
GPM
13
1. Satelliteerahasresultedinamatureviewofthemagnitudeanddistributionofprecipitationacrossourplanet,althoughthereisstillmuchtobedoneintermsofaccuracy,lengthofrecordandspaceandtimeresolutions.
2. Recentmissions(TRMM,Cloudsat,GPM)confirmearlierGPCPplanetaryclimatologicalmeanof~2.7mm/d withinerrorboundsof+/-7%.GPMmeanvaluesslightlyhigher(5-8%)inthetropics thanGPCPandTRMMnumbers,butlowerinhigherlatitudes (overocean).CloudSat confirmsGPCPmeanestimatesinhighlatitudes.
3. BasedonPMWretrievals,planetary-scalevariationsofprecipitationrelatedtoENSOandvolcanoes areevidentintherecord,althoughnosignificanttrendinglobalmeanprecipitation hasbeenfoundforthesatelliteera(1979-present).
1. GPMradarresultsfor2014-2016(includingElNino)betteragreewithsurfacetemperature– rainfallrelationsforPMWresults (includingGPCP)thandidTRMMradarresults.Reasonsforthisareunderinvestigation.
Summary
14
ExtraSlides
15
16
17
TrendsinGlobalPrecipitationDuringSatelliteEra(1979-2013)
EstimatedTrendsrelatedtoGlobalWarming
mm/d/decade
Although the trend in global total precipitation is nearzero (in GPCP analysis), the pattern of observedregional trends (left panel) is related to GlobalWarming (GW) plus inter-decadal signals such as PDOand AMO (ENSO impact is small). Bottom left panelshows trend pattern after PDO effect is removed, abetter estimate of of GW impact on precipitationregional trends and also a pattern closer to thatpredicted by CMIP climate models (bottom right), butwith smaller magnitudes—by factor of 2-3.
Gu,AdlerandHuffman(2016)ClimateDynamics
ObservedTrends(GPCP)
TrendsfromCMIPensemble
EstimatedTrendDistributionforSatelliteEraduetoGlobalWarming
Climatology
Wetgettingwetteranddrygettingdrierinmostareaswithafewexceptions
Trend
18
TrendsinPrecipitation(1900-2010)duetoGlobalWarming[withaerosoleffecttakenout]
Gaugesoverland;“reconst-ruction”overwater
ClimatemodelforcedbyobservedSST,etc.
ClimatemodelforcedbyCO2
Composite,i.e.,meanofthethreeotherfields
Gu andAdler(2015)J.Clim.
“RECONS”isareconstructionofglobalprecipitationbySmithetal.(2012)J.Atmos.Oceanic Tech. 19