The prior knowledge at what date the monsoon will set in and withdraw is of vital importance for more than a billion people in India. More lead time for monsoon forecasts is crucial for planning agriculture, water management, economic growth, and political stability. "We deliver our early forecast for the Indian population and stakeholders to help them to take appropriate decisions - from the farmer’s field to the central government," says Elena Surovyatkina.
Meteorological services currently forecast the monsoon onset only two week in advance and only for Kerala state on the southern tip of India. In contrast, the PIK-team delivers a long-term forecast of both, the onset and withdrawal dates for the central part of India. The long-term forecast means 40 days in advance for the onset date, and 70 days in advance for the withdrawal date, and is the earliest forecast of the Indian Summer Monsoon. The team issued a forecast for the onset of the monsoon on May 8th and a forecast for the monsoon withdrawal on July 27th. Both forecasts lie within a prediction interval: between 14th and 22nd of June, 2017 – the monsoon set in over the central part of India on June 16th - and between 7th and 17th of October – the monsoon withdrew from central India 15th-16th of October, 2017. "Hence, in 2017 we proved again that such early forecast is possible," says Elena Surovyatkina.
The region of forecast is the central part of India where the prediction of monsoon timing has never been made. It locates in the area of the Eastern Ghats (EG), namely in the southeastern part of Maharashtra state, and the western part of Chhattisgarh state and the northern part of Telangana state (the geographical point (20°N, 80°E). The novel approach is based on the teleconnection between the Eastern Ghats (EG) and North Pakistan (NP) - Tipping Elements of Indian Summer Monsoon. While meteorological services use precipitation, wind characteristics, and the outgoing long wave radiation values, the new approach relies on near-surface air temperature and relative humidity. "Our predictions and the meteorological service forecast are complementary. This will help to improve the predictability of monsoon timing across the Indian subcontinent."
"We observed that climate change affects Indian Summer Monsoon in two aspects: in the last decade, the intensity of monsoon rainfalls in the central part of India has increased, and the withdrawal of the monsoon has been delayed. This is due to an increase in spring temperatures and a slower cooling in autumn which is linked to global warming", explains Surovyatkina. Heavy rains might trigger floods and a spilling of dams, and lead to a potential damage of the crop at harvest stage. "An early forecast of the withdrawal date can help to manage dams and reduce losses," says Surovyatkina. “Forecasting the withdrawal date becomes even more important since flooding risks affect millions of people.”
More information on the forecasting of the Indian Summer Monsoon: https://www.pik-potsdam.de/services/infodesk/forecasting-indian-monsoon
