Prediction of monsoon has been a tricky business, but scientists may have finally cracked the code. By the looks of it, a more accurate way of predicting monsoons could be within grasp.

Knowing when the rains will arrive is important for farmers, for planning their next crop.

The traditional way of forecasting monsoon has been by the application of statistical tools on historical rain data for broad predictions, which is not very accurate. Forecast of weather parameters such as temperature, humidity and the arrival of rains can be measured only days before. This is not very useful since farmers need to plan well in advance.

Lucrezia Terzi, a researcher at the Belgian Nuclear Research Centre (SCKCEN), has come up with a new way of predicting the monsoon, by measuring how much Beryllium-7, an isotope of the element Beryllium, is present in the air.

Presenting a paper on the subject at a science and technology conference organised in Vienna by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) last week, Terzi said that she tested the method on Indian monsoon last year and was able to predict it accurately nearly two months in advance.

The CTBTO held the conference to showcase how its technologies and system for detecting nuclear explosions can be applied elsewhere — such as monsoon prediction.

The CTBTO runs the International Monitoring System (IMS) of 300-odd stations, which can sense vibrations, hear sounds or smell noble gases (such as Xenon, Krypton) ‘radionuclides’ (such as Beryllium-7). If a country sets off a nuclear explosion clandestinely, — whether underground, underwater or in the atmosphere — the IMS will know all about it in minutes.

Terzi used two of the IMS stations, in Dubna, Russia, and Melbourne, Australia, to measure the concentration of Beryllium-7 (Be-7), an isotopic variant of the element Beryllium (isotopes are variants whose atoms have fewer or more neutrons in their nuclei compared with the ‘regular’).

She chose Be-7 because it is created only in the stratosphere, when cosmic rays hit and break the nuclei of nitrogen and oxygen. Due to the sun warming the oceans differently at different latitudes, and the spin of the earth, water-bearing air moves up and down in circular fashions, which is the basic cause of the monsoons. When air flows down from the stratosphere (upwards of 33,000 feet from the earth’s surface), it brings with it some Be-7. Terzi says that there is a strong connection between the amount of Be-7 and the timing of monsoons.

She said that with her method, one could predict the Indian monsoon 52 days in advance, with a margin of error of three days. The current methods predict three weeks in advance, with margin of error of five days.

“The beauty of it is that it is so simple,” Terzi told BusinessLine , on the sidelines of the conference. However, she said she had not presented her method to the Indian authorities yet.

Martin Kalinowski, an expert who works at the CTBTO and has co-authored an article on the subject with Terzi in Nature magazine, cautions that more work needs to be done before the Be-7 method could be declared scientifically valid.

Calling it “exploratory”, Kalinowski said it is an evolving technology.

M Ramesh’s participation in the Science and Technology 2019 conference was sponsored by the CTBTO

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