Precipitation Characteristics in Eighteen Coupled Climate Models

Monthly and 3-hourly precipitation data from twentieth-century climate simulations by the newest generation of 18 coupled climate system models are analyzed and compared with available observations. The characteristics examined include the mean spatial patterns, intraseasonal-to-interannual and ENSO...

Full description

Saved in:

Bibliographic Details
Published in:	Journal of climate 2006-09, Vol.19 (18), p.4605-4630
Main Author:	Dai, Aiguo
Format:	Article
Language:	eng
Subjects:	20th century Atmospheric models Climate Climate change Climate models Climate system Convection Corrections Diurnal Diurnal cycle Diurnal variations Earth, ocean, space El Nino El Nino phenomena El Nino-Southern Oscillation event Exact sciences and technology External geophysics General circulation models Global climate Global climate models Hydrologic data Intraseasonal variations Latitude Meteorological research Meteorology Modeling Modelling Oceans Planetary boundary layer Precipitation Precipitation data Rain Rainfall Rainfall intensity Rainfall patterns Satellite observation Sea surface Sea surface temperature Simulations Snow Southern Oscillation Storm tracks Storms Studies Surface temperature TRMM satellite Tropical convection Tropical rainfall Tropical Rainfall Measuring Mission (TRMM) Tropical regions Variability Warm seasons Water in the atmosphere (humidity, clouds, evaporation, precipitation)
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Monthly and 3-hourly precipitation data from twentieth-century climate simulations by the newest generation of 18 coupled climate system models are analyzed and compared with available observations. The characteristics examined include the mean spatial patterns, intraseasonal-to-interannual and ENSO-related variability, convective versus stratiform precipitation ratio, precipitation frequency and intensity for different precipitation categories, and diurnal cycle. Although most models reproduce the observed broad patterns of precipitation amount and year-to-year variability, models without flux corrections still show an unrealistic double-ITCZ pattern over the tropical Pacific, whereas the flux-corrected models, especially the Meteorological Research Institute (MRI) Coupled Global Climate Model (CGCM; version 2.3.2a), produce realistic rainfall patterns at low latitudes. As in previous generations of coupled models, the rainfall double ITCZs are related to westward expansion of the cold tongue of sea surface temperature (SST) that is observed only over the equatorial eastern Pacific but extends to the central Pacific in the models. The partitioning of the total variance of precipitation among intraseasonal, seasonal, and longer time scales is generally reproduced by the models, except over the western Pacific where the models fail to capture the large intraseasonal variations. Most models produce too much convective (over 95% of total precipitation) and too little stratiform precipitation over most of the low latitudes, in contrast to 45%–65% in convective form in the Tropical Rainfall Measuring Mission (TRMM) satellite observations. The biases in the convective versus stratiform precipitation ratio are linked to the unrealistically strong coupling of tropical convection to local SST, which results in a positive correlation between the standard deviation of Niño-3.4 SST and the local convective-to-total precipitation ratio among the models. The models reproduce the percentage of the contribution (to total precipitation) and frequency for moderate precipitation (10–20 mm day-1), but underestimate the contribution and frequency for heavy (>20 mm day-1) and overestimate them for light (
ISSN:	0894-8755 1520-0442