The four-month-long rainy season of the Indian Summer Monsoon, or Southwest Monsoon, is the most anticipated and economically important weather phenomenon to affect the Indian subcontinent. With 70% of the 1.3 billion population relying on agriculture for their livelihoods, India is heavily dependent on the annual monsoon rainfall.
In pre-monsoon season temperature increases across parts of India. In May 2016, India recorded its highest-ever temperature of 51 degrees Celsius. This year, the thermometer has regularly reached more than 40 degrees across many parts across India, with the highest temperature recorded so far of 45 degrees in central parts of the country. In such severe conditions the whole country is waiting for the monsoon.” When does monsoon start?” - is the most vital question now.
Timing is crucial for agriculture and resource management
The team lead by Elena Surovyatkina forecasts the timing of the upcoming monsoon onset 40 days in advance. The timing can be crucial for planning agriculture as well as for water and energy resources management, and for taking appropriate decisions at various levels from farmers' fields to the government of India. "We started our test forecasting in May 2016. Since then we made four forecasts for the onset and withdrawal dates for last two years. I am happy to report that the results of our forecasts turned out to be successful," says Surovyatkina.
The forecast relies on observations of near-surface air temperature and relative humidity from both the ERA-40, the European Center for Medium-range Weather Forecasts (ECMWF) and NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA. The methodology is based on the theory of critical transitions. "We consider the onset of monsoon as a critical point of the transition from pre-monsoon to monsoon: once temperature and relative humidity overcome the critical values, the monsoon season starts," explains Elena Surovyatkina. Currently, the team is working as part of the project "EPICC - East Africa, Peru, India Climate Capacities", funded by the German Federal Ministry for the Environment (BMU).
Weblink to the PIK monsoon page with more information: https://www.pik-potsdam.de/services/infodesk/forecasting-indian-monsoon
