南京市区不同下垫面对近地层温度影响

Impacts of different underlying surfaces over urban district in Nanjing on surface layer temperature

利用南京市内设立在4种不同典型下垫面的自动气象观测站逐时温度资料,采用对比分析方法,分析不同下垫面对城市近地层温度的影响。结果表明,城市绿地在日出日落后温度变化最明显,春秋两季温度变化速率超过2℃/h,夏冬两季也可达1.2℃/h,这使得绿地夜晚温度较低;城市水体日出日落后的温度变化速率最小,因而城市水体夜晚温度较高,尤其在春秋两季最为明显;城市中的生活区和校区在日出日落后温度变化速率稍高于城市水体,夜间温度一般高于绿地,低于水体。另外,不同下垫面对城市气温的季节变化也有影响,城市水体秋冬季节温度高,绿地在夏季温度低,使得温度的平均年变化减小;城市生活区和校区温度的季节变化特征与前两者相反。温度年变化在四季转换过程中的不均匀性在不同下垫面上也有不同的特点,在冬半年,城市水体温度的月际变化较大,而绿地月际变化小,夏半年则出现完全相反的情况。

The data of automatic weather station has been used to analyze the temperature properties at different underlying surfaces in Nanjing. The results showed that temperature change rate after sunrise and sunset in greenbelt was much higher than that on other surfaces, which was over 2 ℃/h in spring and autumn, 1.2 ℃/h in summer and winter. Temperature in greenbelt was lower than that in other sites at night. Waterarea had the lowest temperature change rate after sunrise and sunset, so its temperature was higher, that was especially obvious in spring and autumn. Temperature change rate in living area and school was a little higher than that in water area, but temperature in living area was higher than greenbelt both during daytime and nighttime, lower than water area. Features of seasonal variation of temperature were also different at differentunderlying surfaces. In autumn and winter, temperature in water area was high, and in summer temperature in greenbelt was very low, so that these two types of underlying surfaces could reduce the mean annual variation of city temperature. Living area and school had opposite effects. Furthermore, annual variation of temperature was asymmetric. In winter half-year, monthly variation of temperature was more obvious in water area than that in greenbelt, but in summer half-year, the situation was the reverse.