gcss pacific cross-section intercomparison (gpci): status and progress
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National Aeronautics and Space Administration
Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California
GCSS Pacific Cross-section Intercomparison (GPCI): status and
progress
Models and observations are analyzed along a transect from stratocumulus, across shallow cumulus, to deep convection
ISCCP Low Cloud Cover (%)
Courtesy C. Hannay
GPCI is a working group of the GEWEX Cloud Systems Study (GCSS)
Participation of 23 climate/weather prediction models
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National Aeronautics and Space Administration
Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California
-1 2 5 8 11 14 17 20 23 26 29 32 35latitude (degrees)
AIRS relative humidity (%)
1000
900
800
700
600
500
400
300
200
100
pre
ssure
(hPa) J
JA
2003
01 02 03 04 05 06 07 08 09 0
Satellite observations of cloud regime transitions along GPCI transect
CloudSat cloud occurrence
Model ensemble mean tracks MISR observations of cloud-top height ... HOWEVER there is large variability among models
Cloud top height
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National Aeronautics and Space Administration
Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California
ECMWF fvMMF GEOS5
LWC
CloudSat liquid water content (LWC) forJJA 2006 along GPCI transect
LWC LWC
CloudSat
LWC from models and CloudSat are similar in magnitude
BUT very different in structure:
PBL growth is not as clear in CloudSat;
Large differences over ITCZ
LWC (mg.m-3)
Li et al., 2009
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National Aeronautics and Space Administration
Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California
Boundary layer height from GPS RO observations
ISCCP Low Cloud Cover (%)
Boundary layer height (2001-2004)
GPS RO ECMWF
GPCI is being used for preliminary studies of future GPS RO missions
Von Engeln et al, GRL, 2005
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National Aeronautics and Space Administration
Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California
GPCI practical developments
• General GPCI paper is now circulating among co-authors
• Model results are assembled and organized at the DIME website at: http://gcss-dime.giss.nasa.gov/gpci/modsim_gpci.html.
• LES experiments forced by ECMWF re-analysis are currently being carried out
• GPCI framework is being used for:(i) model intercomparison and evaluation(ii) Evaluation of satellite observations(iii) Preliminary studies of future missions
Future of GPCI and connections to other initiatives (e.g. CFMIP, EUCLIPSE, YOTC) will be discussed later
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