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Ann. Geophys., 21, 1197-1207, 2003
www.ann-geophys.net/21/1197/2003/
© European Geosciences Union 2003
Diagnostic study of errors in the simulation of tropical continental precipitation in general circulation models
J. Srinivasan
Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, 560012, India
Abstract. A simple diagnostic model
has been used to identify the parameters that induce large errors in the
simulation of tropical precipitation in atmospheric General Circulation models
(GCM). The GCM that have been considered are those developed by the National
Center for Environmental Prediction (NCEP), the National Center for Atmospheric
Research (NCAR) and the Japanese Meteorological Agency (JMA). These models
participated in the phase II of the Atmospheric Model Inter-comparison Project
(AMIP II) and simulated the climate for the period 1979 to 1995. The root
mean-square error in the simulation of precipitation in tropical continents was
larger in NCEP and NCAR simulations than in the JMA simulation. The large error
in the simulation of precipitation in NCEP was due to errors in the vertical
profile of water vapour. The large error in precipitation in NCAR in North
Africa was due to an error in net radiation (at the top of the atmosphere). The
simple diagnostic model predicts that the moisture converge is a nonlinear
function of integrated water vapour. The large error in the interannual
variance of rainfall in NCEP over India has been shown to be due to this
nonlinearity.
Key words. Meteorology and
atmospheric dynamics (precipitation; tropical meteorology; convective
processes)
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