Abstract
A statistical analysis has been applied to obtain a better understanding of the variations of the surface climate in Southeast Asia. In particular, we have depicted the detailed features of the changes in the surface air temperature of Hong Kong (HK) during the past 115 years. Analysis of the timeโfrequency spectra of the wavelet transform indicates that although seasonal variations account for most of the temperature variations, strong signals also exist on subseasonal, interannual, and interdecadal time scales. Though the strong seasonal cycle is marked by a minimum temperature in February (and then in January) and a maximum temperature in July (and then in August), strong variations on the subseasonal and interannual time scales occur mostly in February and then in March. It is also found that a rising tendency exists in the longโrecorded temperature data, with a rate of 0.09โ0.15 ยฐC per decade.
Temperature variations in HK are strongly related to changes in the regional and remote atmospheric circulation on various time scales. The East Asian monsoon circulation is the main factor controlling the seasonal cycle and the subseasonal and interannual variations of the HK temperature during winter. The subseasonal and seasonal variations of the temperature are also associated with changes in the atmospheric circulation over the North Pacific, which is closely linked to the East Asian jet stream. Strong signals are also found in both this midโlatitude circulation and the El Niรฑoโsouthern oscillation phenomenon when the interannual variability of the HK temperature is apparent. Copyright ยฉ 2002 Royal Meteorological Society.