Decadal scale oscillations and trend in the Indian monsoon rainfall
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The emerging need for extended climate prediction requires a consideration of the relative roles of climate change and low-frequency natural variability on decadal scale. Addressing this issue, this study has shown that the variability of the Indian monsoon rainfall (IMR) consists of three decadal scale oscillations and a nonlinear trend during 1901–2004. The space–time structures of the decadal oscillations are described. The IMR decadal oscillations are shown to be associated with Atlantic Multidecadal Oscillation (AMO), Atlantic tripole oscillation and Pacific Decadal Oscillation (PDO). The sea surface temperatures (SSTs) of the North Pacific and North Atlantic Oceans are also resolved as nonlinear decadal oscillations. The SST AMO mode has high positive correlation with IMR while the SST tripole mode and SST PDO have negative correlation. The trend in IMR increases during the first half of the period and decreases during the second half. The IMR trend is modified when combined with the three decadal oscillations.
KeywordsPacific Decadal Oscillation Decadal Variability Atlantic Multidecadal Oscillation Indian Monsoon Rainfall Pacific Decadal Oscillation Index
This work was supported by National Science Foundation (grants ATM-0830062 and ATM-0830068), National Oceanic and Atmospheric Administration (grant NA09OAR4310058) and National Aeronautics and Space Administration (grant NNX09AN50G). This work formed a part of the Ph.D. thesis of Lakshmi Krishnamurthy at George Mason University.
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