摘要
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A relationship between mean sea level pressure gradient between Azores High (AH) and Icelandic Low (IL) hereafter called North Atlantic Oscillation Index (NAOI) and the frequency of cyclonic disturbances over North indianOcean is investigated using 98 years of date (1891-1988). The analysis is carried out on monthly, seasonel, annual anddecadal scales. Similar studies are also done for North West Pacific ocean cyclonic disturbances. It is nohced that thenumber of cyclonic disturbances over North indian Ocean during monsoon season (June-September) as well as onannual scale is significantly correlated with NAOI. However for pre (April-May) and post (October-November-December) monsoon seasons frequency of cyclonic disturbances do not bear similar relationship with NAOI. Thestudy also shows that decadal scale variability of cyclonic disturbances during the summer monsoon over North Indian Ocean has a remarkable correspondence with the decadal variability of NAOI.
