Regional climate change and local urbanization effects on weather variables in Southeast China

摘要

This paper presents the analyses of regional climate change features and the local urbanization effects on different weather variables over Southeast China. The weather variables considered are: daily mean (T_m), minimum (T_(min)), and maximum (T_(max)) near surface air temperature, diurnal temperature range (DTR), relative humidity (RH), and precipitation (P). With analysis of two datasets (a station dataset for the period from 1960 to 2005 that is mainly used and a grid dataset for the period 1960-2000), this study reveals that the trends in the variations of these weather variables can be separated into two periods, before and after 1984. Before 1984, there were no significant urbanization effects, and T_(min), RH, and P steadily increased but T_(max) decreased, resulting in a considerable decrease in DTR and a slight decrease in T_m. After 1984, T_(min) and T_(max) increased considerably, and the urbanization influence on T_(m;n), but not T_(max), is observable. The urbanization effect causes an extra increasing trend in T_(min) with a rate of about 0.6°C/decade and, accordingly, extra decreasing trends in DTR and RH. The analysis of the seasonal trends reveals that the urbanization influence results in a near-uniform increase of T_(min) for all four seasons and a strong decrease of RH in summer and autumn. Moreover, there is no significant change in P at the annual scale and an increasing rate of 11.8%/decade in summer. With the urbanization influence, a considerable increase in P is noticeable at the annual scale; specifically, the increasing rates of 18.6%/decade in summer and 13.5%/decade in autumn are observed.