NEW DELHI: Rainfall deficit of 43% as on Saturday will be reduced once the monsoon covers the entire country next month but the season, already affected by El Niño, may not get the climatic cushion of Indian Ocean Dipole (IOD) to offset the impact this year. In effect, there is now a very high probability of the overall monsoon ending up in more than 10% deficit as predicted by IMD. Though a positive IOD does not guarantee a good monsoon rainfall, it often reduces the damage caused by El Niño. As a result, some El Niño years have still seen near-normal rainfall because a strong positive IOD supported the monsoon. In the recent past, 2023 is an example where positive IOD largely offset the strong El Nino, helping India get near-normal seasonal rainfall. IOD is a climate phenomenon that describes the difference in sea surface temperatures between the western and eastern parts of the Indian Ocean. It is one of the key factors that influences the summer monsoon, along with El Niño–Southern Oscillation (ENSO).
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At present, neutral IOD conditions prevail over the Indian Ocean. “Forecasts from the Monsoon Mission Coupled Forecast System (MMCFS) indicate that neutral IOD conditions are likely to persist through the southwest (summer) monsoon season,” said the IMD. A neutral IOD means it does not actively strengthen or weaken the southwest monsoon. So other climate drivers such as El Niño become important in impacting the seasonal rainfall. Keeping in view the prevailing El Nino,IMD has already predicted ‘below normal’ rainfall this rainy season (June-Sept) with 60% probability of its being deficient (more than 10% of overall deficit during June-Sept), triggering a fear of drought. The nationwide deficit of 43% in cumulative rainfall (June 1-27) is already reflecting in states with many of them recording shortfall of 50% or more. Meghalaya recorded the highest deficit of 82% followed by Gujarat (79%), Manipur (71%), Chhattisgarh (68%), Jharkhand (66%), Maharashtra (59%), Uttar Pradesh (56%), Odisha (52%) and Bihar (50%). The situation in Madhya Pradesh with 41% shortfall also looks quite critical as the state falls in the ‘monsoon core zone’ – rain-fed area, which largely depends on monsoon rainfall for farming operations. Peninsular India, except Andhra Pradesh, also presents a scary picture as Karnataka, Kerala, Tamil Nadu and Telangana reported more than 30% deficit despite being covered by the monsoon 2-3 weeks ago. The rainfall data over four homogenous regions shows the highest deficit of 57% in central India followed by 44% in east & northeast India, 30% in south peninsular India and 27% in northwest India.