Cooling effects of a river and sea breeze on the thermal environment: a case of Kuala Terengganu, Terengganu, Malaysia

Abstract

A series of sea breeze observations have been carried out along the Terengganu river in the state of Terengganu on the east coast of the Peninsular of Malaysia. These observations were carried out during the north-east monsoon months ofNovember and December, 1993. Wind and temperature data were measured at the height of about I.S m above the ground along the three traverses on both sides of the river which is approximately 10 km long that perpendicular to the coast and then the results were presented in a horizontal cross-section. Generally, the formation of sea breeze of the speed of ~ 4.1 ms-1 was observed capable in reducing the ambient air temperature of about 2.0° to 4.0°C. Although the effect of sea breeze can be traced further inland along the river, its cooling effects, however, were well marked at the estuary of the Terengganu river than at the 7th km interior area of Kuala Terengganu. The difference in the temperature decrease was observed in the order of 1.7° and 2.4°C from the inland to the coastal areas, respectively. During the sea breeze episode, most of the coastal field stations indicated a slower temperature increase than the field stations located in the interior area. Furthermore, the effect of sea breeze in reducing ambient air temperature was well marked above the river (stations on bridges) than stations on both sides of the river. Simultaneously, an overall time-lag increase in relative humidity was observed during the fall of ambient air temperature, owing to the effect of sea breeze. In general, the establishment of sea breeze cooling effect was significantly felt about 3 to 6 hours period i.e., between 14.00 and 20.00 (Malaysian Local Time) which was varied between stations; longer period was experienced by stations located at or near the coastal area than stations further inland.