The South Asian summer monsoon, the Indian Ocean and related teleconnections* Annalisa Cherchi
https://global.gotomeeting.com/join/932307501
Abstract The South Asian summer monsoon (SASM) is a seasonal phenomenon characterized by wind reversal and intense precipitation during austral summer. It provides about 80% of annual rainfall for the whole south Asian region, influencing the life of more than a billion of people leaving there. Despite its seasonality, it has large variabilities at many timescales (from sub-seasonal to decadal). A weaker (or even a stronger) than normal monsoon may have dramatic socio-economic consequences for the region, thus it would be useful to have reliable predictions of its timing and intensity. However, because of the large internal climate variability at play, the inherent complexity of the phenomenon and the role of external forcing, the prediction of the monsoon is far from satisfactory to be useful. Among external forcing, the SASM is largely influenced by the El Nino Southern Oscillation (ENSO) and by the near Indian Ocean, that has been experiencing a warming larger than any other tropical basins since the 1950s. The relationship with ENSO is known since the beginning of the last century, but it has been found to weaken in recent times. New research provided insights on the influence from the Indian Ocean Dipole (IOD) and its potential trigger of the ENSO-monsoon teleconnection. The IOD is the dominant mode of variability of the tropical Indian Ocean and it is also highly variable in time, depending on how it evolves within the seasons (i.e., from boreal summer to autumn) it can have large impacts on the South Asian summer monsoon characteristics, specifically over India. The SASM also have important remote influences, like over the Mediterranean, thus creating a complex network of teleconnections among the different players. In this seminar I will show some aspects of these important and complex teleconnections linking the South Asian summer monsoon climate to ENSO, the Indian Ocean and the Mediterranean as steps of the research activity I have been involved in during the last years.