Extended Arctic winter hits rains
An extended winter in the Arctic and the Greenland region will affect India’s south-west monsoon rainfall, according to a new study done by the researchers at National Institute of Oceanography.
They have gathered the rainfall data for the last 2,000 years over Indian subcontinent using geological records. When they compared the data with the Arctic and Greenland region’s cold years they found a surprise correlation between the two phenomenon.
“There is a teleconnection between the two. When you have low temperature there, it spreads the lot of ice and snow cover in the Himalayas. Then low-level tropical atmosphere temperature will change and it is affecting the Indian summer monsoon rainfall,” P. Divakar Naidu, chief scientist, National Institute of Oceanography, Goa told this paper on the sidelines of the Indian Science Congress here.
The researchers have analysed a particular group of micro organisms which thrived during the good monsoon season (June to September) from the ocean sediments. “If these organisms are in abundance (during this period), then we can assume that it was a good monsoon year,” he said.
“We have the instrumental rainfall records only for 100 years. This period will not be enough to see the cyclic pattern of the monsoon — such as if there is any periodicity existing in monsoon and what controls the long time records,” he added.
In the last 100 years, atmospheric CO2 levels have increased, it is called artificial increase. “Whether the monsoon is driven by the natural changes or during the artificial effects is the objective of our study,” he explained.
The earth’s orbital variation also can affect the monsoon as it can receive a lot of sunlight. The study has been conducted at three places in the Arabian Sea and the Bay of Bengal. They collected sediment cores from the ocean bottom.
If these organisms are in abundance (during this period) in the ocean, then we can assume that it was a good monsoon year." — P. DIVAKAR NAIDU, Chief scientist, NIO, Goa