SOLAR DIMMING AND URBAN HEATING AT HONG-KONG

Over the last 35 years solar radiation in Hong Kong has decreased by more than one-third. During the same period the population doubled and the total use of fossil fuels increased more than sevenfold. A surface energy balance model was used to demonstrate the opposing effects of the decline in irradiance and the increase in anthropogenic heat production on air temperature. Differences between air temperatures measured in the city and at an upwind, unpopulated island were used to verify the simulated decrease in the urban heat-island by day and increase at night, leading to an unchanged mean air temperature difference. The implications of these results for climate change in the rapidly urbanizing Pacific Rim region are discussed briefly.