Springer Online Journal Archives 1860-2000
Summary An intercomparison of the characteristic features of the Indian summer monsoon has been carried out for the monsoon months (June to September) of 1995 using the mean monthly analyses/forecasts from the operational centres of ECMWF, JMA, UKMO and NCMRWF. This exercise was undertaken to determine how well the large scale monsoon features over India were reproduced in the operational output in 1995 and also to assess the performance of the NCMRWF assimilation/forecast system. For this purpose, precipitation, mean sea level pressure, circulation features in the lower (850 hPa) and upper (200 hPa) troposphere, mid-tropospheric (500 hPa) temperature, and latent heat flux were examined. It is found that all the dominant features of the Indian summer monsoon are fairly well represented in the analysis and medium range forecasts of the ECMWF, JMA and UKMO. The NCMRWF output agrees well with those from other centres except for a sharp gradient in precipitation across the west coast which was not captured well in the forecasts due to the relatively coarse horizontal resolution of the model compared to that used at other operational centres. Other important features of the southwest monsoon, like the heat low over the northwestern part of the country, the lower level westerly jet and upper level easterly jet etc. are found to be reasonably well represented in the output of all operational centres. The JMA analyses and forecasts possessed greater levels of moisture compared to the NCMRWF output possibly due to the synthetic moisture information used at JMA. The evolution characteristics of the summer monsoon onset over the southern tip of India are found to be comparable in the output of JMA and NCMRWF.
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