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Tellus (2004), 56A, 308327 Copyright C Blackwell Munksgaard, 2004 Printed in UK. All rights reserved TELLUS

Summary: Tellus (2004), 56A, 308327 Copyright C Blackwell Munksgaard, 2004
Printed in UK. All rights reserved TELLUS
Evaluating climate model simulations of tropical cloud
, Met Office, Hadley Centre for Climate Prediction
and Research, FitzRoy Road, Exeter, EX1 3PB, United Kingdom
(Manuscript received 10 June 2003; in final form 28 December 2003)
The representation of tropical cloud and its radiative effects in the Hadley Centre climate model are evaluated using
a combination of Earth observation data and meteorological reanalyses. It is shown that useful information regarding
the model's physical parametrizations can be obtained by considering cloud radiative effects and cloud types in terms
of `dynamical regimes', defined in terms of sea surface temperature and large-scale vertical motion. In addition to
comparisons with observed top-of-atmosphere radiation budget parameters and total cloud amount, information is
obtained through direct comparisons of International Satellite Cloud Climatology Project (ISCCP) cloud types, defined
according to cloud top pressure and optical depth, with corresponding model diagnostics. An analysis of the atmosphere-
only model, HadAM3, demonstrates how errors in the albedo and outgoing long-wave radiation can be related to the
simulation of particular cloud types in the different dynamical regimes. Inconsistencies between the simulations of the
various cloud types and the top-of-atmosphere radiation budget are also highlighted. A version of the model including
several new cloud-related parametrizations is then examined. A more consistent comparison with the observed radiation
budget and cloud amounts is obtained, although deficiencies in the simulation still remain. A parametrization for the


Source: Allan, Richard P. - Department of Meteorology, University of Reading


Collections: Geosciences