This paper evaluates the performance of eight
state-of-art IPCC-AR4 coupled atmosphere-ocean general
circulation models in their representation of regional
characteristics of atmospheric water balance over South
Asia. The results presented here are the regional climate
change scenarios of atmospheric water balance compo-
nents, precipitation, moisture convergence and evaporation
(P, C and E) up to the end of the twenty-second century
based on IPCC AR4 modelling experiments conducted for
(A1B) future greenhouse gas emission scenario. The
AOGCMs, despite their relatively coarse resolution, have
shown a reasonable skill in depicting the hydrological cycle
over the South Asian region. However, considerable biases
do exist with reference to the observed atmospheric water
balance and also inter-model differences. The monsoon
rainfall and atmospheric water balance changes under A1B
scenario are discussed in detail. Spatial patterns of rainfall
change projections indicate maximum increase over north-
west India in most of the models, but changes in the
atmospheric water balance are generally widespread over
South Asia. While the scenarios presented in this study are
indicative of the expected range of rainfall and water
balance changes, it must be noted that the quantitative
estimates still have large uncertainties associated with them.

Last Updated: 2011-07-13