Coastal Atmospheric Boundary Layer Characteristics with Rainfall Activity over Goa during ARMEX-2002
N. V. Sam (1)
(1) Indian Institute of Technology, Delhi
Abstract
There is a considerable understanding of homogeneous marine and land boundary layers, but the application of this knowledge is complicated by the inherent heterogeneity of the coastal zone. Most coastal environments are modified by the adjacent ocean, the coastal topography and the land-sea thermal contrasts. Complex feedbacks occur between the atmosphere, ocean and land. Recent research has focused on thermally driven circulations, orographically-forced events and land-falling storms due to mesoscale and large-scale interactions. This paper investigates the characteristic features involved in the variability of the Coastal Atmospheric Boundary Layer (CABL) over Goa (a west coastal Indian station) during South West Monsoon (SWM) 2002. A one-dimensional multi¡Vlevel PBL model with a TKE-ƒÕ closure scheme was used for this purpose.
This study was made possible as a component of the Arabian Sea Monsoon Experiment (ARMEX), wherein detailed observations enabled the study of CABL characteristics influencing the convective processes over Goa during two different heavy rainfall events respectively in June and August 2002 and a suppressed convective episode during July 2002.
One of the important findings of the study was the heterogeneity that was noticed in the convective atmosphere during short and prolonged convection episodes when heavy precipitation was observed and a relatively calm atmospheric condition with little or no precipitation. During July 2002 the inhibition of boundary layer moisture convergence as a result of reduced convective heating in the middle and upper troposphere, and the resulting lack of compensating upward motion is reflected well from the simulated surface fluxes and suppressed turbulent kinetic energy (TKE), boundary layer height (BLH). The model also generates the vertical profiles of potential temperature, specific humidity, zonal and meridional wind that compare reasonably well with the observations available from Goa.
Key words: ARMEX, CABL, SHF, LHF, TKE, SWM
Submittal Information
Name :
Date :
Nelson V. Sam
31-Jul-04-15:30:43
Organization :
Theme :
Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi, India
Theme 1
Address :
Presentation :
Centre for Atmospheric Sciences, IIT Delhi, Hauz Khas, New Delhi - 110016