Tropical circulation indices and performances of Indian summer monsoon rainfall

Abstract

The interannual relationships between the summer monsoon rainfall over all India (AIR), northwest India (NWR), and peninsular India (PIR), and seven different tropical circulation indices (TCIs) (based on mean sea level pressure) over five selected tropical stations, three over the Indian Ocean namely Agalega (A), Cocos Island (C), Il-Nouvelle (I), and two over the land stations namely New Delhi (N) and Malacol (M) have been examined for 30 years’ period (1953-1982). The names of the indices are (i) TCI (A-M), (ii) TCI (A-N), (iii) TCI (A-C), (iv) TCI (C-M), (v) TCI (C-N), (vi) TCI (I-N), and (vii) TCI (I-M). The results indicate that significant strong and inverse relationships exist between (a) TCI (C-M) of concurrent August and AIR, NWR, and PIR, (b) TCI (C-N) of antecedent February and AIR, NWR, and PIR and (c) TCI (I-N) of antecedent May shows significant and direct association with AIR and PIR. Stability analysis of different TCIs shows that TCI (C-M) of concurrent August and TCI (C-N) of antecedent February show consistently significant relationship over the successive 25 years’ period. © 2009 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.