Cloud populations, vertical structure and their periodicity at the south of the equatorial Indian Ocean during CINDY2011

The field campaign CINDY2011/DYNAMO/AMIE/LASP (hereafter CINDY) aimed to reveal the mechanism to initiate the convection of the Madden-Julian Oscillation (MJO). During CINDY, we JAMSTEC deploly the research vessel (R/V) Mirai with the C-band Doppler radar at the southeastern corner (8S, 80E) of the CINDY sounding / radar array. This study reports the cloud population and their spatiotemporal variation, to investigate the spatial, especially longitudinal, structure of the disturbances.

The deep and widespread convective systems were observed only in the former half of the Ocrober when MJO convections were inactive. The convective activity were with the period of several days. The temporal variations are similar to the results on Addu Atoll at (Eq, 73E) (Zuluaga and Houze 2013). The two-day periods in the latter half of the October, reported in Johnson and Ciesielski (2013), were also observed but by the shallow cumulus and congestus without deep convections. For the November MJO event, the shallow cumulus / congestus were basicaly dominant, while the tall convective clouds appeared with the periods of several days. Diurnal cycle were also apparent.