Indian weather events impact on ocean/atmosphere/land climate

Weather and climate timescales interactions are studied as follows. We simulate intraseasonal-to-interannual climate changes with an Indian ocean/Tropical atmosphere/land Model of Intermediate Complexity (ICM). We use daily data of wind (QuikSCAT) and rain (TRMM) between 1999 and 2006 to investigate the role of weather events over the Indian Ocean in setting the low fluctuations of the Tropical climate. Spectral data analysis show that about 55% of the QuikSCAT variability and 80% of the TRMM rain occur in the submonthly (2-30 day) range on average over the basin. Data are then used to force the Indian Ocean component of the ICM in experiments that differ only by their forcing, which is either daily- or monthly- averaged. Results show that the sub-monthly atmospheric fluctuations feed the intra-seasonal to inter-annual ocean variability. The impact on sea level is mostly felt at the equator, south of it, and in the Bay of Bengal in the [30-to-90] day range, the impact on salinity is mostly felt once per year in the Bay of Bengal, both signals affecting the SST south and north of the equator. The ICM results are then examined in terms of consquences on the wind and rain climate changes between 1999 and 2006.