A comparison of the significant features of the marine boundary layers over the east central Arabian Sea and the north central Bay of Bengal during MONEX-79

Abstract

Low-level mean and turbulence data from the National Centre for Atmospheric Research (NCAR) Electra aircraft in conjunction with dropwindsondes and ship observations during MONEX.79 were used to compare the typical structures of the Arabian Sea and the Bay of Bengal monsoon boundary layers. Analysis indicates significant differences in-both mean and turbulence structures, The presence of a strong low level Somali jet over the east central Arabian Sea significantly increases turbulent fluxes and variances. Monsoon boundary layer over the north central Bay of Bengal in which wind speeds were significantly reduced showed a decrease in heat and momentum fluxes by approximately 10 to 30 % throughout the boundary layer as compared to the Arabian Sea region. Boundary layer heights over the Arabian Sea were two to three times greater than those observed over the Bay of Bengal. Shear and buoyancy production in the turbulent kinetic energy budget are found to be significant to roughly twice the height in the boundary layer over the Arabian Sea as against the Bay of Bengal.