Marine Boundary layer characteristics during active, suppressed and transition phases of convection noticed during BOBMEX-99 field phase were studied by employing a multi-level, one-dimensional PBL model with one and half order TKE-e closure.
It was noticed that more transportation of fluxes of sensitive and latent heat from the surface layer into the boundary layer was taking place during active convection whereas it was found to be negligible during suppressed convection.
Significant contribution of buoyancy generation along with shear generation of turbulent kinetic energy was seen during active convection.
Boundary layer simulation over the Bay of Bengal during BOBMEX-99 by NCMRWF global circulation model.
Swati Basu and R.K. Paliwal, NCMRWF, New Delhi.
For the BOBMEX-99 period the global T80 model of NCMRWF was re-run with a more realistic diffusivity coefficients derived from “Non-local closure (NLC)” scheme.
This new NLC scheme mixed the surface fluxes with the upper atmosphere more efficiently in heavy convective condition.
This had shown an improvement in rainfall forecast for the whole BOBMEX period. The circulation in forecast was improved.
Surface Radiative Fluxes over the Bay of Bengal and their variations during BOBMEX-99.
K. Gopala Reddy and G. Nageswara Rao, Andhra University, Visakhapatnam.
The variations of the radiative fluxes over the central Bay of Bengal (13°N, 87°E) during BOBMEX-99 were examined on hourly and daily basis.
The net short wave (SW) flux during day-time varied between 249 and 461 W/m2. The net long wave (LW) flux varied between -51 and -0.7 W/m2. The net radiative flux varied from 207 to 455 W/m2 during day- time.
The albedo varied from a minimum of 0.05 to 0.13. There was a clear inverse relation between albedo and Sin h.
Ocean-atmosphere interaction and synoptic weather conditions in association with the two contrasting phases of monsoon during BOBMEX-1999.
S.P. Ghanekar, V.R. Mujumdar, P. Seetaramayya and U.V. Bhide, Indian Institute of Tropical Meteorology, Pune.