AN OVERVIEW OF MERRA: VALIDATION AND ......AN OVERVIEW OF MERRA: VALIDATION AND CHALLENGES FOR...

AN OVERVIEW OF MERRA: VALIDATION AND CHALLENGES FOR FUTURE REANALYSESCHALLENGES FOR FUTURE REANALYSES

Presented by Michael Bosilovich

with contributions from many in the GMAOy

NASA’S MODERN ERA RETROSPECTIVE-ANALYSIS FOR RESEARCH AND APPLICATIONS (MERRA)

2002 Proposed Objective: Improving the water and energy cycle representation in a reanalysis

GEOS5 system development including NASA global climate model with NCEP GSI data assimilation

Nov 2007 – External User Review Group endorses the Validation Review of GEOS5 for MERRA

Production began in May 2008 Production began in May 2008

Provisional release of 9 yrs data in Dec 20089 yrs. data in Dec 2008

Began realtime pro-duction in Apr 2010

Currently 1979 through May ‘10 are available

NASA’S MODERN ERA RETROSPECTIVE-ANALYSIS FOR RESEARCH AND APPLICATIONS (MERRA)

1979-present (continuing as it is feasible)

½° horizontal resolution (72 model levels, sfc-strat)

1 hourly surface and 2D diagnostic datay g Including complete budgets and extensive meteorology,

lowest model level states

6 hourly 3-Dimensional atmospheric analysis

3 hourly 3-D model background including diagnostics, 3 hourly 3 D model background including diagnostics, coarse resolution

>70 Tbs online storage, many portals (incl. subsetter) g , y p ( )up to realtime processing > 31 years of data

CHALLENGE AND ADVANTAGE OF REANALYSIS

1973 – 77K Obs every 6hrs 1987 – 550K Obs every 6hrs

1979 – 325K Obs every 6hrs 2006 – 4.2M Obs every 6hrs

ASSESSING PRECIPITATION SKILL

Taylor Diagram of Global Annual precipitation skill ofprecipitation skill of existing reanalyses e.g. Bosilovich et al (2008)

PRECIPITATION ANOMALIESPRECIPITATION ANOMALIES

http://gmao.gsfc.nasa.gov/ref/merra/atlas/

Calculating Budgets

ANAtqvqvPE

tqv

g

Complete budgets are available including all t d i dtendencies and analysis increments

Water (all phases), O KEOzone, KE, Enthalpy, Included

Also, land-onlybudgetsbudgets

Tremendous effort by Max Suarez, Larry Takacs andLarry Takacs and Randy Koster

Ocean Precipitation ( mm day-1)Gl b l i i i

WATER AND ENERGY CYCLES TIME SERIESGlobal Ocean

3.6

3.8

4.0

4.2

4.4Ocean Precipitation ( mm day )

3.1

3.3

3.5

1

Global Precipitation

2.6

2.8

3.0

3.2

3.4

2.5

2.7

2.9

mm

day

-1

Land Precipitation ( mm day-1)

2.4

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

GPCP CMAP MERRA JRA Interim NCEPR2

2.3

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

GPCP CMAP MERRA JRA Interim NCEPR2

Land

2.62.83.03.23.4

p ( y )

Global P trend mostly over Ocean

Land

1.61.82.02.22.4

over Ocean Land, taken together,

are comparable with 1.4

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

GPCP CMAP MERRA JRA Interim NCEPR2

little apparent trend

GLOBAL WATER BALANCEGLOBAL WATER BALANCE

FwPEwvw

Nov98 NOAA15 Jul99 QSCAT

tt

ANA

0 42 9Global P, E, Qvinc (mm day-1)

Jul99 QSCAT Jan01 NOAA16 Aug02 NOAA170.1

0.20.30.4

2.62.72.82.9

g Oct02 AIRS Nov05 NOAA18

0 3-0.2-0.10.0

2 22.32.42.5

-0.4-0.3

2.12.2

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

P E Qvinc

NET SURFACE AND TOA IMBALANCENET SURFACE AND TOA IMBALANCE

6.0Ocean Surface Flux Anomalies (W m-2)

0.02.04.0

-6 0-4.0-2.0

-8.0-6.0

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

Global surface net imbalance is improving in time, mostly changing over Ocean

LE (87.7) Hs (11.7) SWdn (195.8) LWdn (342.7)

changing over Ocean The Ocean net imbalance is decreasing in incoming SW

radiation and increasing LE

SPATIAL EFFECT OF AMSU (ESTIMATED) ON MERRASPATIAL EFFECT OF AMSU (ESTIMATED) ON MERRA

Increment Change (mm day‐1)Precipitation Change (mm day‐1) Increment Change (mm day 1) 2000‐08 minus 1990‐97

Precipitation Change (mm day 1) 2000‐08 minus 1990‐97

Increases in SH midlatitude and Indian OceanSPCZ i i l l d i SPCZ increase is also related to moist convergence

African decrease needed more attention

Many analyses can help understanding/validation/development Many analyses can help understanding/validation/development 2003-2004 LH Flux Difference from a Remotely Sensed estimate

(Vinukollu et al 2010)

CORRECTING THE TIME SERIESCORRECTING THE TIME SERIES

Increment Change (mm day‐1)2000‐08 minus 1990‐97

Analysis increments contain the information Analysis increments contain the information to remove trend artifacts induced by step function changes in observing system input.Robertson et al (2010) From Robertson et al (2010)

BASIN-SCALE PRECIPITATIONBASIN SCALE PRECIPITATION

GEOS5

CPC US ¼ gridded gauge dataDail Jan 1 2003 Dec 31 2004

mm day-1

MERRA Daily, Jan 1 2003 – Dec 31 2004 Area average over the Mississippi River Basin domain

TROPOPAUSE FOLD

TROPOPAUSE FOLD

KATRINA AT LANDFALLKATRINA AT LANDFALL

mm hr-1

ANDREW AUG 24, 1992

ANDREW AUG 24, 1992

ERS observations overlayy MERRA Obs (including O-F and O-A) to be

available for user access soon

BEGINNING RESEARCH

MERRA Precipitation shows skill compared to GPCP, relative to other reanalysesreanalyses

Trends are on the order of other reanalyses, but the bias is much improved

Energy balance smallest in the recent Energy balance smallest in the recent period, ~8Wm-2 imbalance

Global P, E (mm day-1)

Remaining issues in reanalyses: model bias appears as trends in conjunction with the changing observing system can affect many

0.20

0.30

0.40

0.50

2.70

2.80

2.90

3.00c observing system, can affect many

aspects of the reanalysis Researchers must evaluate the

processes important to their-0.20

-0.10

0.00

0.10

2.30

2.40

2.50

2.60

Qv i

nc

P,E

processes important to their project; Analyzed observations should help

-0.302.20

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

P E Qv Incr

THANK YOUTHANK YOU Home - http://gmao.gsfc.nasa.gov/merra/

D t htt //di i f /MDISC/ Data - http://disc.sci.gsfc.nasa.gov/MDISC/ Atlas -

http://gmao.gsfc.nasa.gov/ref/merra/atlas/ Discussion – Discussion

http://merra-reanalysis.blogspot.com/

merra-questions@listserv gsfc nasa gov merra questions@listserv.gsfc.nasa.gov Michael.Bosilovich@nasa.gov

850mb specific humidity from Bangui (64650), compared to MERRA grid point, monthly mean anomalies

AMAZON TIME SERIESAMAZON TIME SERIES

10.0Amazon Precipitation (mm day-1)

4 0

6.0

8.0

0.0

2.0

4.0

an eb

Mar

Apr ay un Ju

l

ug ep Oct ov ecJ F M A Ma Ju J Au S O No D

MERRA (99-06) MERRA (79-98)GPCP (99-06) GPCP (79-98)

Amazon precipitation generally increases, but th i l h hift i th l lthere is also a phase shift in the annual cycle

More water in the soil, after AMSU assimilation

ATMOSPHERIC HEATINGATMOSPHERIC HEATING

Global Heating Rates (W m-2)

20.0

25.0

85.0

90.0

15.080.0

NA

ST

5 0

10.0

70 0

75.0 AN

MS

0.0

5.0

65.0

70.0

9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8

Moist Processes

Analysis

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008