The summer monsoon of 2019 began with a massive deficit in the all-India June rainfall of about 33% of the mean. This led to considerable anxiety since a large deficit in June had occurred last in the summer monsoon of 2014, which had turned out to be a drought.

We have addressed the question of whether the massive deficit of 42% in rainfall over the Indian region in June 2014 can be attributed primarily to the El Niño. We have shown that the variation of convection over the Northern part of the Tropical West Pacific (NWTP: 120–150E, 20–30N) plays a major role in determining the all-India rainfall in June with deficit (excess) in rainfall associated with enhancement (suppression) of convection over NWTP.

Interannual variation of Indian summer monsoon rainfall (ISMR) is linked to El Niño-Southern oscillation (ENSO) as well as the Equatorial Indian Ocean oscillation (EQUINOO) with the link with the seasonal value of the ENSO index being stronger than that with the EQUINOO index. We show that the variation of a composite index determined through bivariate analysis, explains 54% of ISMR variance, suggesting a strong dependence of the skill of monsoon prediction on the skill of prediction of ENSO and EQUINOO.

The monsoon rainfall in 2014 is likely to be less than the long term average, with a chance of almost one in four of it being a drought, according to the forecast of the India Meteorological Department. The expected occurrence of an undesirable phenomenon – the El Niño over the Pacific Ocean, is considered to be a major factor in determining the fate of the monsoon this year. (Editorial)

Original Source

The Indian summer monsoon rainfall (ISMR) has remained remarkably stable during the last 140 years. The ISMR has varied between 70% and 120% of the long-term average of about 85 cm. Monsoon seasons with ISMR of less than 90% of the average are considered to be droughts, whereas those with more than 110% rainfall are considered as excess rainfall seasons. Although the variation is not large (Figure 1), it has a substantive impact on our agriculture and gross domestic product (GDP).

Under the project 'Seasonal Prediction of the Indian Monsoon' (SPIM), the prediction of Indian summer monsoon rainfall by five atmospheric general circulation models (AGCMs) during 1985-2004 was assessed. The project was a collaborative effort of the coordinators and scientists from the different modelling groups across the country.

This is a brief response to Sunita Narain's thought-provoking piece on the role of monsoon in our lives. As scientists actively involved in understanding the Indian monsoon and its prediction, we have attempted to elucidate what we know about this intriguing phenomenon, which is a tantalizing mixture of order and chaos, the problems of predicting it and our expectation of the progress that could be achieved in the near future.

In this paper, we suggest criteria for the identification of active and break events of the Indian summer monsoon on the basis of recently derived high resolution daily gridded rainfall dataset over India (1951

After an early onset over Kerala on 23 May 2009, further advance of the monsoon over the Indian region was delayed by about two weeks with the monsoon restricted to the west coast and southern
peninsula until 24 June. This resulted in a massive deficit in the all-India rainfall of 54% of the long term average for this period.

Sub-seasonal rainfall fluctuations, characterized as active and weak spells during the Indian monsoon season (June to September) is an important component of the variability of the Indian monsoon rainfall.