Observational aspects of atmospheric boundary layer features over west coast of India with emphasis to southwest monsoon

Abstract

The Atmospheric Boundary Layer is the lowest portion of the atmosphere newlinewhere significant exchange of momentum, moisture, heat and mass takes place newlinebetween the Earth s surface and the atmosphere. It is the layer which is well mixed newlineand strongly influenced by the thermal and dynamical features of the underlying newlinesurface, determines the weather and climate of the region. Turbulence is newlineresponsible for exchange of properties within the ABL which is associated with the newlinelapse rate (thermal turbulence) as well as wind shear (mechanical turbulence) newlinewithin the layer. Properties of ABL depend on many factors including soil newlineproperties, vegetation, geographical location, topography, surface roughness, newlineprevailing wind conditions, agricultural practices, etc. The influence of sea breezeland newlinebreeze systems combined with the coastal topography causes complexities in newlinethe ABL features. The ABL over the mid latitudes was studied very vastly, whereas newlinein Indian scenario the studies are limited. In the Indian context, they are mainly newlineconfined to a few experiments such as MONEX (Monsoon experiment), IIOE newline(International Indian Ocean Experiment), ISMEX (Indo-Soviet Monsoon newlineExperiment), MONTBLEX (Monsoon Trough Boundary Layer Experiment), etc. and newlinesome observational sites over the main land regions and a few coastal stations newlinewhere sophisticated instruments are available. The properties of ABL over west newlinecoast where the atmosphere is more vulnerable to extreme events and climate newlinechange, need to be explored to know about the influence of weather systems on newlinethe ABL parameters. ABL height is considered as one of the climate forcings. A newlinebetter understanding of the ABL is needed for accurate parameterization of the newlineABL over the regions in weather and climate models as well. newlineWest coast experiences four seasons namely pre-monsoon, monsoon, post newlinemonsoon and winter. During the monsoon shallow clouds are seen over the region newlinewhereas during the post monsoon mainly convective clouds are seen.