How well do three GCMs capture the present climate ?

AF 07

GCM data:

single control runs for

i) ECHAM4 1971-2000

ii) CSIRO9 Mk II 1961-1991

iii) HadAM3 1960-1990

Reanalysis data ("observations"):

i) NCEP 1970-2002

ii) ERA 1979-1993

JJA climatology

sea level pressure

Obs 1

HadAM

CSIRO

ECHAM

Obs 2

DJF climatology

sea level pressure

Obs 1

Obs 2HadAM

CSIRO

ECHAM

JJA climatology

integrated moisture

Obs 1

Obs 2HadAM

CSIRO

ECHAM

DJF climatology

integrated moisture

Obs 1

Obs 2HadAM

CSIRO

ECHAM

JJA 500hPa height

deviation from annual mean

Obs 1

Obs 2HadAM

CSIRO

ECHAM

DJF 500hPa height

deviation from annual mean

Obs 1

Obs 2HadAM

CSIRO

ECHAM

JJA climatology 700 hPa wind

OBS

CSIRO

HadAM

ECHAM

DJF climatology 700 hPa wind

OBS

CSIRO

HadAM

ECHAM

Walker circulation 5S - 5N (DJF)

OBS HadAM

ECHAM CSIRO

Summary

i) Any GCM data used for climate change assessment should be validated over the region of interest.

ii) Temporal and spatial biases should be understood and accounted for where necessary.

iii) Single pixel values should be avoided and aggregations at the skill level of the GCM used.