Ensemble simulations of Eurasian snow-depth anomalies and their influence on the summer Asian monsoon

The effect of springtime surface conditions over Eurasia on the monsoon cir culation is addressed by using several simulations with the model used by t he European Centre for Medium-Range Weather Forecasts (ECMWF). The simulati ons have been specially designed to investigate whether the Eurasian snow-a nomaly is a passive response to the tropical forcing, implying that the ult imate relationship exists only between the El Nino/Southern Oscillation (EN SO) and the monsoon as suggested by previous studies, or plays an active in dependent role in the monsoon modulation. Preliminary results suggest that the Eurasian snow depth is probabilistically predictable, and that it does influence the seasonal-mean monsoon independently of the ENSO phase. Theref ore, proper observations and simulations of the Eurasian snow field can pro vide an additional and independent contribution to monsoon prediction.