COLA AGCM simulation of the effect of anomalous spring snow over Eurasia on the Indian summer monsoon

The ability of the Center for Ocean-Land-Atmosphere Studies Atmospheric General Circulation Model to capture the inverse snow-monsoon relation observed in satellite-derived data is tested. The effect of initial enhanced and reduced spring Eurasian snow mass on the evolution of the subsequent Indian summer monsoon is examined through 11-member ensemble integrations from 1 March to 1 October The results of the sensitivity experiment indicate that remote responses from the snow-mass anomalies include significant changes in the sensible-heat flux, latent-hear flux and sea level pressure, leading to changes in summer precipitation over the land mass of the Indian subcontinent. Fur the pre-monsoon season, the ensemble average of the temperature of the atmospheric column for enhanced snow mass is anomalously colder over large-scale regions of the Eurasian continent compared with the ensemble average for the reduced snow mass. Low-level south-westerlies associated with monsoonal circulation are increased. The results indicate the importance of land-surface processes in the evolution of the monsoon circulation and lend hope to the use of Eurasian spring snow mass towards improved forecasting of the summer monsoon.