Sea-Breeze Circulation over Jakarta, Indonesia: A Climatology Based on Boundary Layer Radar Observations

Abstract

Characteristics of sea-breeze circulation over the tropical site of Jakarta, Indonesia, have been documented based on analyses of satellite images and data from long-term L-band boundary layer radar measurements carried out at Serpong (6.4°S, 106.7°E). Inspection of satellite imagery reveals that a sea-breeze front develops well along the northern coastal plain of West Java and propagates inland until its structure is deformed over complex topography. It is found that the sea-breeze signal detected by the boundary layer radar is most well defined during the dry season months of July?October. In all of these months, radar observations indicate a late afternoon intensification of sea-breeze flow in the 0.5?0.8-km height range between 1700 and 1800 LT, which is not elucidated upon by surface measurements. The effect of weather conditions on the sea-breeze pattern is investigated by using a cloudiness index derived from data of incoming solar radiation. The results show that sea-breeze intrusion over the radar site occurs earlier during more cloudy days, whereas the intensity of sea-breeze circulation weakens accordingly. In the rainy season months of January and February, diurnal wind variation is characterized by daytime onshore flow enhancement, which is not likely attributed to sea-breeze circulation.