摘要
用近50年逐日气象观测记录和城市发展统计资料分析了东北平原腹地3个不同规模城市,即大城市长春,中等城市延吉和山区小城镇临江的年和季节平均气温、最高最低气温等,发现其差别很大,其排序不一定同城市化速率(人口和国内生产总值GDP)、土地利用或能见度趋势对应。但气温日较差趋势均与城市化速率成比例。3个城市气温趋势均表现为变暖,且最低气温趋势大于最高气温趋势;冬季变暖强于夏季。这说明影响夜间或冬季气温的才是城市热岛的主要驱动因子。冬、夏最高气温趋势排序一致,除临江外,最低气温趋势排序与最高气温相反。临江冬季最低气温趋势最强,可能与其特殊地理环境造成的弱风气候有关。最低气温趋势排序与城市化速率排序大致相同,最高气温趋势排序相反。综合对比分析表明,这3个城市气候变暖差异的主要因子不可能是土地利用,而是城市人为热释放和空气污染,后者主要影响夜间的射出长波辐射。二者的影响范围趋势应该同城市化速率成比例,对气温趋势有明显影响。其次,不能忽略地理环境因子对气温趋势及其排序的影响。不过,气温日较差在一定程度上可以削弱城市地理因素等的影响,其趋势是一个反映城市化对气候影响的的合适指标。研究还表明,需要重视空气污染对长波辐射的影响并应该在数值模式辐射参数化中加以考虑。
This study aims to investigate the importance of local thermal factors contributing to urban heat island (UHI) for the cities of Changchun, Yanji, and Linjiang in Northeast China over the past 50 years. Changchun is a large city, the capital of Jilin Province, and Yanji is a middle one, while Linjiang which locates in a lap of hills, is a small town situate in the down of heavy industry centre of Northeast China. Statistics shows that the rank order of their urbanization rates (URT) is the same as the city sizes. The observation shows that their minimum temperature trends (MNTT) are much greater than their maximum counterparts (noted as MXTT), and the winter trends are greater than their summer counterparts. The rank order of the MNTT is contrast to the MXTT and approximately the same as the URT, while the difference of MNTT and MXTT is proportional to the URT. The land use, anthro- pogenic heating, and air pollution are three major factors for UHI, and the later two are proportional to the URT. Inter-comparison reveals that the air pollution and anthropogenic heating are key factors for the UHI, because their combination could explain the major characteristics of the trends and orders, while the land use doesn't. The results also manifest the importance of local geographical environment in Linjiang, which lead to a weak wind climate that has the thermal factors localized. The localization may be one of the causes that produced the strongest MNTT and MXTT in Lingjiang in wintertime. Nevertheless, the difference of the MNTT and MXTT can reduce, to some ex- tent, the influence of the geographic factors on the temperature trends because it is proportional to the URT. Hence, the difference can be regarded as a good climate index in representing urbanization. Besides, the results also imply that the important impact of air pollution (aerosols) on long-wave radiation should he considered not only in observation, but also in numerical model of atmosphere. A suggestion is to increase green land, and meanwhile to reduce air pollution and anthropogenic heating for mitigating city climate warming.
出处
《气候与环境研究》
CSCD
北大核心
2012年第3期353-364,共12页
Climatic and Environmental Research
基金
国家自然科学基金40775048、41075058
国家重点基础研究发展规划项目2006CB400504
国家科技支撑项目2007BAC29B04
关键词
城市化
城市热岛
土地利用
人为热排放
空气污染影响
urbanization, heat island effect, land-use, anthropogenic heating, air pollution influence