摘要
利用北京市市区4个站点和郊区3个站点40a的气候资料,分析了北京市城、郊平均气温、降水、日照、能见度和相对湿度的变化特征。研究发现:40a来北京市城、郊年平均气温明显上升,城区气温平均升温幅度为0.43℃/10a,郊区气温平均升温幅度为0.21℃/10a。北京市热岛效应明显增强,城、郊气温年代变化特征中,城、郊温差20世纪60年代最小,90年代最大;在城、郊气温年际变化特征中,1961～1977年城、郊温差较小,1978～2000年城、郊温差较大。在城、郊气温季变化特征中,冬季城、郊季平均气温温差最大,春季城、郊季平均气温温差最小。近几年虽然高温(≥35℃)日数明显增多,但是年最高气温变化不大,只有1997年、1999年和2000年年最高气温超过38℃。北京市年日照时数呈明显下降趋势,城区40a来日照时数下降幅度为78.9h/10a,城、郊日照时数差异随季节有不同的变化,并且秋季最大,1961～2000年秋季郊区日照时数比城区平均多0.34h。40a来北京市年降水量略有减少,且年降水量变化幅度很大,城区40a来降水量减少幅度为45.2mm/10a,由于城市化影响,下垫面性质改变,城区<10mm的降雨日数远远小于郊区,40a间城区<10mm的降雨日数比郊区少603d。1981～2000年间北京市城区水平能见度2月份、5月份、9月份和10月份较好,北京市城、郊低值能见?
Variations of mean temperature in Beijing city are analyzed in this paper by using climatological data of 4 stations in city and 3 stations in suburb. We found that the difference of temperature was great in daily, seasonal, annual and decade, the difference of temperature between city and suburb was largest in winter and the mean seasonal temperature in city was higher 1.11℃ than that in suburb, while the difference was smallest in spring; For the inter-annual variability of temperature, the difference was little from 1961 to 1977, while the difference was great from 1978 to 2000, so the heat island effect was reinforced from 1978 to 2000; the difference of temperature was least in 1960's, whereas the difference was maximal in 1990's; the number of high temperature day (≥35℃) was going up obviously ,but the highest temperature was not changed greatly .the mean annual temperature was increasing apparently during last 40 years , and it was increasing by 0.43℃/10a in city and 0.21℃/10a in suburb. the sunshine time decreased obviously in Beijing, and the decreasing range was 78.9 hours/10a during the last 40 years, and the difference in autumn between city and suburb was largest in whole year. The precipitation also reduced recent years, furthermore the change of yearly precipitation was great, and the decreasing range of precipitation was 45.2mm/10a in Beijing city. Following the development of city, the days when the precipitation was less than 10mm were more in city than in suburb. The visibility was great in February, May, September and October in Beijing, the number of low visibility (<4km) was increasing ,the visibility was decreasing in recent years and the visibility in city was obviously lower than in suburb. The relative humidity was also decreasing in recent years in city , and the decreasing range was 1.6% for every 10 years, further more the relative humidity in city was less than in suburb, it showed dry island effect.
出处
《干旱气象》
2003年第3期63-68,共6页
Journal of Arid Meteorology
基金
国家重点科技项目<中国短期气候预测系统研究>加强课题的支持.
