Can global warming make Indian monsoon weather less predictable?

Abstract

Reliable medium range prediction of monsoon weather is crucial for disaster preparedness. Weather in tropics, controlled by fast growing convective instabilities is, however, intrinsically less predictable than that in extra-tropics. Increased frequency and intensity of extreme rain events in the tropics in the backdrop of global warming has a potential for further decreasing the potential predictability of the tropical weather. Using nonlinear dynamical techniques on gridded daily rainfall data over India for 104 years (1901-2004), here we show that the deterministic predictability of monsoon weather over central India in the latest quarter of the period has indeed decreased significantly compared to that in the earlier three quarters. The decrease of initial error doubling time from approximately 3.0 days to 1.5 days is consistent with higher frequency of extreme events and increased potential instability of the atmosphere in the recent quarter. To overcome the increased difficulty in predicting monsoon weather, significant increase in efforts to improve models, observations and enhancement of computing power would be required.