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 circulation is addressed by using several simulations with the model used by the European Centre for Medium-Range Weather Forecasts (ECMWF). The simulations have been specially designed to investigate whether the Eurasian snow-anomaly is a passive response to the tropical forcing, implying that the ultimate relationship exists only between the El Nino/Southern Oscillation (ENSO) and the monsoon as suggested by previous studies, or plays an active independent 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. Therefore, proper observations and simulations of the Eurasian snow field can provide an additional and independent contribution to monsoon prediction.