A study on air-sea exchange processes and conserved variable analysis overthe Indian Ocean with INDOEX IFP-99 data

The exchange properties across the Marine Boundary Layer influence atmosphe ric convection and determine to a large extent the atmospheric circulation in the tropics. In view of these phenomena, an analysis of the surface para meters such as sea-surface temperature, air temperature, wind speed, moistu re and cloud cover along the ORV Sagar Kanya and Ronald H. Brown cruise tra ck was carried out. An attempt was made to examine the changes in these par ameters while the ship was passing across the ITCZ region. The humidity was found to be considerably high over the ITCZ than non-ITCZ regions. The air-sea interaction processes were studied by computing the radiation f luxes (short-wave and longwave) and the turbulent heat fluxes (sensible hea t and latent heat) using semi-empirical models. Over ITCZ region a net heat loss was found which can be attributed to large convergence, strong convec tive activity and dense cloud cover, leading to drastic reduction in short- wave radiation. Latitudinal and longitudinal variation of surface meteorolo gical parameters and turbulent fluxes were studied to establish a link with the prevailing convective and clear weather regimes along the cruise track s. A conserved variable analysis of the conserved variable such as potential t emperature, virtual potential temperature, saturation equivalent potential temperature and specific humidity is carried out at every point of upper ai r observation from Ronald H. Brown. The values are estimated up to a maximu m of 3 km to cover the boundary layer. In the ITCZ region due to the convec tive mixing deeper boundary layers are formed, where a double structure is observed. The Marine Boundary Layer Height is also estimated using thermody namic profiles.