Variability of NAO, northern and southern hemisphere temperature in relation to Indian summer monsoon rainfall rainfall. S.B. Kakade and S.S. Dugam Email: [email protected] Abstract In recent decades, Indian summer monsoon rainfall is not showing significant association with northern hemispheric surface air temperature in winter season but shows consistent and satisfactory linkage with NAO related parameters. It suggests the necessity to understand the variability and relationship of NAO with northern and southern hemispheric temperature anomaly in relation to the monsoon circulation over Indian subcontinent. 50-year running Correlation coefficients between northern hemispheric surface air temperature anomaly and Indian summer monsoon rainfall suggests that the significant (direct) association between them for the period 1923-94. Similar analysis for the relationship between northern and southern hemispheric (south of 30°S) temperature anomaly during winter season is performed. It reveals that the relationship between these two temperature fields is statistically significant (direct) except for the period 1925-92. 50-year running correlation coefficients between NAO and southern hemisphere (south of 30°S) in winter season suggest that the relationship is negative from 1901 to 1924 (though it is not significant) and becomes positive from 1925 onwards with statistically significant relationship from 1932 till today. Similar analysis is performed for the relationship between NAO and northern hemispheric surface air temperature anomaly. This analysis suggests that the direct association between NAO and northern hemisphere temperature is statistically significant for the period 1923-94 only. The correlation analysis between winter-NAO and seasonal temperature anomaly over south of 30°S, for 1951-2000, reveals that the relationship is direct and is statistically significant in winter and spring seasons only..Pages: 1535-153
