- According to a recent study which was published in JGR-Atmospheres by researchers from the Indian Institute of Tropical Meteorology and Assam University, the decreasing monsoon rainfall in Northeast India is associated with natural changes in the subtropical Pacific Ocean.
- The study has said that northeast India which is one of the wettest places on the Earth has been experiencing rapid drying especially in the last 30 years.Some places which used to get as high as 3,000 mm of rain during the monsoon season have seen a drop of about 25-30%.
- This study has concluded that this natural changes is associated with the Pacific decadal oscillation(PDO).Its impact on the sea surface temperatures and its interaction with the atmosphere affects the northeast Indian summer monsoon.
- The team used observed rainfall and sea surface temperature(SST) data for the period 1901-2014 for the study.The results show out that the reduction in rainfall during a major part of the last 114 years may be associated with global man-made factors while the trend during the last 36 years is associated with natural phenomena.
- The Pacific Decadal Oscillation(PDO) is a robust,recurring pattern of ocean-atmosphere climate variability centered over the mid-latitude Pacific basin.The PDO is detected as warm or cool surface waters in the North Pacific(poleward of 20°N).
- The Pacific Decadal Oscillation index is the leading empirical orthogonal function(EOF) of monthly sea surface temperature anomalies (SST-A) over the North Pacific(poleward of 20°N) after the global average sea surface temperature has been removed.
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