Summary of Abstract Submission

Abstract Submission No. IO50-07-0002PresentationOral


Raghu Murtugudde*1, Lei Zhou, Dake Chen2, Dake Chen2, Vinu Valsala3, M. K. Roxy3, Harry Hendon4, Subimal Ghosh5, M. Ravichandran6, M. Lengaigne, J. Vialard7, Arnold Gordon, Kyla Drushka8

1 University of Maryland, USA
2 SIO, Hangzhou, China
3 IITM, Pune, India
4 BMRC, Melbourne, Australia
5 IITB, India
6 INCOIS, India
7 IRD, France
8 Columbia University, Univ of Washington, USA


The Indian Ocean is unique in terms of its dominant seasonal monsoon variability with variability at all other time-scales being comparatively smaller. The annual cycle is essentially split into MJO and MISO seasons with the MJOs operating during October-April and MISOs dominating May-September. The transition from MJO to MISO requires a multi-scale approach that includes the global tropical conveyor, viz., the ITCZ and the atmospheric bridge from both the Atlantic and the Pacific Oceans and the oceanic tunnel from the Pacific via the Indonesian throughflow (ITF). The multi-scale interactions at intraseasonal timescales are critical for the seasonal-to-interannual variability of the monsoons and its interactions with the Indian Ocean Dipole/Zonal Mode and ENSO. A specific example will be used to make the case for an international effort on a multi-scale observational-modeling project focused on the MJO-MISO transition in the Indian Ocean. The ITF interacts with the MJO-driven equatorial Kelvin waves that transition to coastal Kelvin waves in the eastern Indian Ocean. The resulting baroclinic instabilities between Java and Australia propagate westward as intraseasonal Rossby waves. These waves are crucial for the mixed layer-thermocline interactions in the southwestern Indian Ocean which is important for MJO genesis. These ITF-MJO interactions also affect the transition to MISO and thus the African-Asian-Australian monsoons and in turn the IODZM and ENSO. The spatio-temporal scale selection of the responses can only be understood in a multi-scale observational-modeling and forecast framework.