A numerical study of the influence of synoptic flow on coastal meso-scale circulations on the East and West Coasts of India

The effect of synoptic flow on the coastal boundary layer and land sea breeze circulation on the west and east coasts has been investigated by a numerical simulation using PSU/NCAR-MM5 mesoscale model. A study on 24th May 2003 during ARMEX observation period shows occurrence of land-sea breeze circulation and formation of thermal internal boundary layer (TIBL) on both the coastal regions in the daytime but of some differences. An early development and accelerated propagation of sea breeze circulation is noticed on the west coast compared to the east coast under the influence of the prevailing southwesterly flow. The strength of the sea breeze is more on the west coast. The mixing heights during daytime in the coastal regions are reduced by the formation of TIBL. The horizontal extent of TIBL is very less (24 km) on the west coast under the complex topographic effect. The sea breeze frontal activity is more intensive on the east coast with vertical velocity of the order of 2-4 m/sec by the retarding influence of southwesterly synoptic flow.