The highest anomaly or difference in rainfall can be expected in Uttarakhand, followed by Madhya Pradesh & Chhattisgarh
A rainy day in Kolkata. Photo: iStock An analysis of monsoon forecast data has suggested that India will experience a monsoon deficit of 25 millimetres (mm) when compared to the precipitation average for the 1996-2013 period. The southwest monsoon is still a couple of weeks away from the Indian subcontinent at the moment.
The analysis — carried out by Akshay Deoras, climate scientist at the University of Reading, the UK — takes stock of three climate models (United Kingdom Meteorological Office, European Centre for Medium-Range Weather Forecasts and National Centers for Environmental Prediction) and combines them to get mean values.
According to Deoras, the continuing progress of El Nino, the warm phase of a climate pattern across the tropical Pacific called the El Nino-Southern Oscillation (ENSO), will have an impact on the southest monsoon.
“The impact of the El Nino on the monsoon is expected to begin from June. Leading climate models are predicting below average seasonal rainfall over many parts of India during June to September,” Deoras told Down To Earth (DTE).
He also spoke about how different monsoon 2023 (an El Nino year) will be compared to the La Nina years:
India generally receives below average seasonal rainfall (June-September) during El Nino events. The onset over Kerala gets delayed by a few days. Multiple pockets of below average rainfall are observed, which are most prominent over central and northwestern parts of India. This also includes the core monsoon zone, which is directly correlated with seasonal mean rainfall of the monsoon over the country. An increase in the frequency and duration of dry spells are generally observed. The conditions reverse during La Nina events.
Like El Nino, La Nina is the cooler phase of ENSO, “a recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean”, according to the United States National Oceanic and Atmospheric Administration.
DTE accessed the raw data of the models used by Deoras and quantified the spatial data to put some context as to what can be expected in the next four months (June to September 2023) in terms of rainfall.
The highest anomaly or difference in rainfall can be expected in Uttarakhand, followed by Madhya Pradesh and Chhattisgarh. Going by regions, Karnataka and Tamil Nadu can expect a normal monsoon season compared to the 1996-2013 period while above average rainfall can be expected in Kerala, Mizoram and Manipur.
Deoras added a word of caution on climate models even as the map presented a grim outlook for the season.
“It must be remembered that not a single climate model is precise. So we’re looking at a large-scale pattern / tendency / signal in these models. The climate models from these three particular centres outperform others given their superior performance over India,” Deoras said.
While excess or deficient rainfall from a climatological perspective manifests through disaster events like floods or droughts, the impact of monsoon runs deeper.
According to Skymet, a weather forecast service provider, 70 per cent of India’s population directly or indirectly depend on the monsoon season while 260 million farmers in the country depend on the monsoon for cropping products like rice, sugarcane, etc.
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