The GCM-Reality Intercomparison Project for SPARC (GRIPS): Scientific Issues and Initial Results

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To investigate the effects of the middle atmosphere on climate, the World Climate Research Programme is supporting the project “Stratospheric Processes and their Role in Climate” (SPARC). A central theme of SPARC, to examine model simulations of the coupled troposphere–middle atmosphere system, is being performed through the initiative called GRIPS (GCM-Reality Intercomparison Project for SPARC). In this paper, an overview of the objectives of GRIPS is given. Initial activities include an assessment of the performance of middle atmosphere climate models, and preliminary results from this evaluation are presented here. It is shown that although all 13 models evaluated represent most major features of the mean atmospheric state, there are deficiencies in the magnitude and location of the features, which cannot easily be traced to the formulation (resolution or the parameterizations included) of the models. Most models show a cold bias in all locations, apart from the tropical tropopause region where they can be either too warm or too cold. The strengths and locations of the major jets are often misrepresented in the models. Looking at three-dimensional fields reveals, for some models, more severe deficiencies in the magnitude and positioning of the dominant structures (such as the Aleutian high in the stratosphere), although undersampling might explain some of these differences from observations. All the models have shortcomings in their simulations of the present-day climate, which might limit the accuracy of predictions of the climate response to ozone change and other anomalous forcing.

aUniversities Space Research Association, Seabrook, Maryland.

bData Assimilation Office, NASA GSFC, Greenbelt, Maryland.

cFreie Universität Berlin, Berlin, Germany.

dMeteorological Research Institute, Tsukuba, Japan.

eNOAA/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey.

fUniversity of Toronto, Toronto, Ontario, Canada.

gYork University, Toronto, Ontario, Canada.

hNCAR, Boulder, Colorado.

iDepartment of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California.

jScience and Technology Corporation, Hampton, Virginia.

kCentre for Global Atmospheric Modelling, University of Reading, Reading, United Kingdom.

lMax-Planck-Institüt für Meteorologie, Hamburg, Germany.

mNASA Goddard Institute for Space Studies, Palisades, New York.

nUnited Kingdom Meteorological Office, Bracknell, United Kingdom.

oCNRM, Météo-France, Toulouse, France.

pGeneral Sciences Corporation, Beltsville, Maryland.

qNASA Langley Research Center, Hampton, Virginia.

rNIESDP, Tsukuba, Japan.

sPCMDI, LLNI, Livermore, California.

tEuropean Centre for Medium-Range Weather Forecasts, Reading, United Kingdom.

uAES, Victoria, British Columbia, Canada.

Corresponding author address: Dr. Steven Pawson, Universities Space Research Association, Data Assimilation Office, NASA Goddard Space Flight Center, Code 910.3, Building 33, Greenbelt, MD 20771. E-mail: pawson@dao.gsfc.nasa.gov

To investigate the effects of the middle atmosphere on climate, the World Climate Research Programme is supporting the project “Stratospheric Processes and their Role in Climate” (SPARC). A central theme of SPARC, to examine model simulations of the coupled troposphere–middle atmosphere system, is being performed through the initiative called GRIPS (GCM-Reality Intercomparison Project for SPARC). In this paper, an overview of the objectives of GRIPS is given. Initial activities include an assessment of the performance of middle atmosphere climate models, and preliminary results from this evaluation are presented here. It is shown that although all 13 models evaluated represent most major features of the mean atmospheric state, there are deficiencies in the magnitude and location of the features, which cannot easily be traced to the formulation (resolution or the parameterizations included) of the models. Most models show a cold bias in all locations, apart from the tropical tropopause region where they can be either too warm or too cold. The strengths and locations of the major jets are often misrepresented in the models. Looking at three-dimensional fields reveals, for some models, more severe deficiencies in the magnitude and positioning of the dominant structures (such as the Aleutian high in the stratosphere), although undersampling might explain some of these differences from observations. All the models have shortcomings in their simulations of the present-day climate, which might limit the accuracy of predictions of the climate response to ozone change and other anomalous forcing.

aUniversities Space Research Association, Seabrook, Maryland.

bData Assimilation Office, NASA GSFC, Greenbelt, Maryland.

cFreie Universität Berlin, Berlin, Germany.

dMeteorological Research Institute, Tsukuba, Japan.

eNOAA/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey.

fUniversity of Toronto, Toronto, Ontario, Canada.

gYork University, Toronto, Ontario, Canada.

hNCAR, Boulder, Colorado.

iDepartment of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California.

jScience and Technology Corporation, Hampton, Virginia.

kCentre for Global Atmospheric Modelling, University of Reading, Reading, United Kingdom.

lMax-Planck-Institüt für Meteorologie, Hamburg, Germany.

mNASA Goddard Institute for Space Studies, Palisades, New York.

nUnited Kingdom Meteorological Office, Bracknell, United Kingdom.

oCNRM, Météo-France, Toulouse, France.

pGeneral Sciences Corporation, Beltsville, Maryland.

qNASA Langley Research Center, Hampton, Virginia.

rNIESDP, Tsukuba, Japan.

sPCMDI, LLNI, Livermore, California.

tEuropean Centre for Medium-Range Weather Forecasts, Reading, United Kingdom.

uAES, Victoria, British Columbia, Canada.

Corresponding author address: Dr. Steven Pawson, Universities Space Research Association, Data Assimilation Office, NASA Goddard Space Flight Center, Code 910.3, Building 33, Greenbelt, MD 20771. E-mail: pawson@dao.gsfc.nasa.gov
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