Tropical Sea-breeze Circulation and Related Atmospheric Phenomena Observed with L-band Boundary Layer Radar in Indonesia

Abstract

High time-resolution data observed with L-band boundary layer radar in the equatorial region of Indonesia during dry season periods have been analyzed. The existence of tropical sea-breeze circulation, whose delectability has been reported in earlier works, is corroborated by performing intercomparisons with rawinsonde and surface meteorological measurements. In addition to well defined circulation, anomalously weak echo patterns corresponding to the induced shear flow is also found to appear in several cases. Its origin can be identified as Kelvin-Helmholtz type of instability which is believed to generate long lived turbulence activity that caused the gradient of potential refractive index to be locally minimum. After seabreeze intrusion, the planetary boundary layer is divided into layers with different characteristics and cannot be considered as a homogeneous atmosphere throughout the daytime. Although quantitative comparison has not been done, it is found that the observed sea-breeze scales do not seem to critically depend on Coriolis factor f as a primary scaling parameter.