A team of Swiss scientists has developed a novel prediction approach that can forecast Indian monsoon’s yearly onset and withdrawal significantly earlier than using previously available methods. Based on a network analysis of regional weather data, the team from the Potsdam Institute for Climate Impact Research and the University of Zurich will soon propose this approach to the Indian Meteorological Department (IMD).
The summer rains are of vital importance for millions of farmers feeding the subcontinent’s population.
“We can predict the beginning of the Indian monsoon two weeks earlier and the end of it even six weeks earlier than before — which is quite a breakthrough given that for the farmers, every day counts,” said lead researcher Veronika Stolbova from PIK and University of Zurich.
“We found that in north Pakistan and the Eastern Ghats, a mountain range close to the Indian Ocean, changes of temperatures and humidity mark a critical transition to monsoon,” Stolbova explained. Conventionally, the focus was always on Kerala.
The scientists tested their method with historical monsoon data. It gives correct predictions for onset in more than 70 per cent and for withdrawal in more than 80 per cent of the considered years.
In addition, the new scheme notably improves the forecasting of monsoon timing during years affected by the global weather phenomenon El Nino-Southern Oscillation (ENSO), particularly in its La Nina phase. This phenomenon significantly alters monsoon timing and decreases the prediction accuracy of existing methods. The major innovation, the authors say, is to combine the network analysis with the subtle statistical analyses of the early warning signals for the monsoon onset and withdrawal.
Global warming due to greenhouse-gas emissions already affects the Indian monsoon and — if unabated — is expected to do even more so in the future.IANS