In what could be bad news for kharif crops rice, sugarcane and maize, a senior scientist at the Indian Meteorological Department (IMD) says that a weather model being tested at the department shows that the monsoon seems headed for another break in September. The scientist did not wish to be identified.
However, the model doesn’t say when the September break could occur and how long it would last. “Sugarcane, maize and rice require a fair amount of moisture in the first half of September,” says I.P.S. Ahlawat, head, agronomy division, Indian Agricultural Research Institute. “The monsoon begins its retreat in the latter half of September. Reduced rainfall at that time won’t do much harm,” he adds.
The summer monsoon is spread over July to end-September, and is crucial to the kharif crop, harvesting of which begins in October. India has two crop seasons, kharif and rabi.
Monsoon Rainfall (Graphic)
The scientist claims that the model being tested was the only one to anticipate, 15 days in advance, the lull in rainfall in the second half of July.
A monsoon break, according to the IMD, is defined as a halt in the passage of the monsoon system and is characterised by low rains over central, north and peninsular India. Though it’s normal for the monsoon to take a one-two week breather every year, the 2002 and 2004 droughts were characterised by three-week long dry spells.
Rainfall and a minimum amount of soil moisture are important for crops. “Monsoon breaks are a reason to worry because they indicate a dip in the soil moisture levels,” says Ahlawat. Being able to anticipate a break, therefore, allows farmers to better plan their kharif sowing.
The 2007 summer monsoon has seen a break during the latter part of July, which has lasted almost two weeks. “The monsoon ran into a weak phase since July, but the situation is improving. We expect enhanced rainfall over central and peninsular India from 4 August,” said IMD spokesperson B.P. Yadav.
However, some atmosphere scientists say that the number of breaks isn’t important. A paper in Current Science, a peer-reviewed research publication, by atmosphere scientists Sulochana Gadgi from the Indian Institute of Science, Bangalore, and P.V. Joseph from the Cochin University of Science and Technology, says that between 1888-1988, they observed zero to three breaks a year. There were years which saw three breaks and yet above average rainfall, they write.
The monsoon model which has predicted the September break has been developed by B.N. Goswami, director of the Indian Institute of Tropical Meteorology in Pune.
The statistical model has been able to correctly predict breaks in previous monsoons, says Goswami.
Goswami’s findings will be published in the forthcoming issue of the American Meteorological Society’s Monthly Weather Review, a peer-reviewed research publication. “The model is being tested at the IMD in Pune, so I’d like to reserve comment on its predictive abilities,” says Goswami.
“The Goswami model is extremely promising, but I can’t confirm anything about a bre-ak in September,” says Madhavan Rajeevan, director, National Climate Centre, Pune.