北京不同区域表面气温的变化特征以及北京市观象台气温的代表性

利用北京地区14个观测站1990～2007年逐日和2004～2007年逐时的2 m气温观测资料,分析了北京城区、郊区、南部山区以及北部山区4个区域表面气温的年变化、季节变化以及春、夏、秋、冬4个季节的日变化特征,指出4个区域的气温变化特征具有明显的差异.在所有时间尺度上城区气温受城市热岛效应影响最大,表现为温度最高,郊区次之,南部山区较低,北部山区最低.1990～2007年4个区域的气温都表现出增温趋势,其中城区增温最明显,增温率明显大于其他区域.城区与其他区域气温的差异有明显的季节变化,城区与郊区、城区与北部山区气温的差异在冬季最大,夏季最小;城区与南部山区气温的差异在夏季最大,春季最小.在气温的日变化方面,城区气温在各个季节的日较差都是最小的,南部山区最大.通过比较作为北京代表站的北京市观象台的气温与4个区域的差异,发现观象台与城区气温在各个时间尺度上的差异都最小,与其他区域存在显著差异,北京市观象台气温主要代表了城区,对其他区域的代表性较差.

Features of the Surface Air Temperature in Different Areas of Beijing and the Representativeness of Beijing Observatory

Using observed daily 2-m air temperature data during 1990-2007 and hourly measurements during 2004-2007 recorded at 14 meteorological stations in Beijing, we investigated the annual, seasonal, and diurnal variations of the surface air temperature among four different areas of Beijing: The urban area (UA), suburban area (SA), north mountainous area (NMA), and south mountainous area (SMA). Distinct features were observed in the four areas. For all time scales, due to the urban heat island effect, the maximum surface air temperature was observed in UA, followed by SA, SMA, while the minimum was in NMA. During 1990-2007, surface air temperatures in all the four areas showed a significant warming trend, with the largest warming rate being in UA. The difference in surface air temperature between UA and the other areas was season-dependent. The difference in surface air temperatures between UA and SA and between UA and NMA were largest in winter and smallest in summer, while the largest difference in air temperatures between UA and SMA occurred in the summer, and the smallest was in spring. The minimum daily range of the surface air temperature was observed in UA in each season while the maximum was in SMA. Comparing the surface air temperature of Beijing Observatory with the four areas, the best fit was with UA while significant differences were observed with the other areas at all time scales.