Summary of Abstract Submission

Abstract Submission No. IO50-05-0009PresentationOral

RELATION BETWEEN THE UPPER OCEAN HEAT CONTENT IN THE EQUATORIAL ATLANTIC DURING BOREAL SPRING AND THE INDIAN SUMMER MONSOON RAINFALL DURING JUNE-SEPTEMBER

Vijay Pottapinjara*1, MS Girishkumar1, S Sivareddy1, M Ravichandran1, R Murtugudde2

1 INCOIS-Hyderabad, India
2 University of Maryland, the US

ABSTRACT :

The El Niņo-Southern Oscillation (ENSO) and the Indian Ocean Dipole/Zonal Mode (IODZM) are the dominant modes in the tropics which influence the Indian Summer Monsoon Rainfall (ISMR) on the interannual time scales although the two modes alone cannot account fot the total variability of the monsoon. So, it is important to find out other tropical teleconnections to the monsoon. Recent studies have identified a teleconnection between the Atlantic Zonal Mode (AZM) which is similar to, but weaker than ENSO, and ISMR, both of which are active during the boreal summer (AZM:June-August; ISMR: June-September). It is known that ENSO-like coupled dynamics are operational in the tropical Atlantic during the AZM events. We attempt to extend this process understanding to seek a predictive relation between the tropical Atlantic and the ISMR based on these known teleconnections. Monthly composite analysis of the zonal surface winds, heat content, and SST in the equatorial Atlantic tells us that signatures of a warm or cold AZM event begin to emerge as early as January of that year. We found significant correlations between the ISMR and, the low level zonal winds in the western equatorial Atlantic and heat content in the eastern equatorial Atlantic in the boreal spring season. Tracking coherent changes in these winds and the evolution of the heat content in the deep tropical Atlantic in the boreal spring may offer the potential for skillful predictions of the ensuing summer monsoon anomalies, especially during non-ENSO years when the predictability of ISMR tends to be low.