Surface Meteorological parameters and the upper ocean temperature profiles up to 100 m were analysed at a stationary location (17.5°N, 89°E) during Phases I and II of BOBMEX-1999.
The variations of heat fluxes and upper ocean thermal structure reflected the synoptic situation over the Bay of Bengal during Phase I, when ocean surface encountered a net heat loss. However, a net heat gain was noticed during Phase II.
Analysis of heat content in the upper oceanic layer (100 m) showed heat loss (gain) during Phase I (Phase II). However, the heat content variations in the near surface layer (40 m) were opposite in nature. This might have resulted in reduction of cyclogenesis during Phase II.
The isothermal layer of Phase I was warmer and showed lesser short- period fluctuations. There was a remarkable decrease in the temperature of the isothermal layer in Phase II subsequent to a prolonged epoch of rainfall during 14-16 August. The abrupt changes (in the isothermal layer) during 16-18 August were noticed accompanied with the quick movement of trough across the ship. Detailed study was required to understand and find the interrelation of these changes.
16 Air-Sea fluxes and diurnal variability of the Marine boundary layer height during BOBMEX-Pilot Experiment
K. Sengupta and M. Venkata Ramana, Space Physics Laboratory, VSSC, Trivandrum.
This paper described the variation of sensible and latent heat fluxes along the BOBMEX cruise track over the Bay of Bengal using the data collected from sensors installed on a retractable boom on ORV Sagar Kanya during BOBMEX-Pilot experiment.
The sensible and latent heat fluxes were computed using Bulk aerodynamic method, which uses the standard Monin-Obukhov similarity theory. Sensible heat flux was found to vary between -6 to +25 W/m2 and latent heat flux varied between +30 to +230 W/m2. These fluxes were found to vary with surface wind speed.
Friction velocity was also computed and varied between 0.04 to 0.4 m/s for a 1-10 m/s wind speed range. The computed drag coefficient was found to vary from 1.09 x 10-3 to 1.53 x 10-3 and also found a strong dependence on stability (z/L). An empirical relation was derived to describe the variation of neutral drag coefficient (CDN) with surface wind speed (U10) over the Bay of Bengal.
17 Marine boundary layer characteristics over the Bay of Bengal during BOBMEX- 99.
A.N. V. Satyanarayana, U.C. Mohanty, N.V. Sam and A.K. Das, Indian Institute of Technology, New Delhi