格点资料在城市气候变化研究中的应用

为了解浙江省城市增暖的地域差异及其受热岛效应影响的程度,对杭州、宁波、温州3个城市的气候变化趋势进行了分析。为减少观测资料的非均一性,运用最优插值法将浙江省1971—2010年62个站点资料的信息植入到NCEP月平均温度资料的背景场中,得到格距为5 km的格点资料。研究结果表明:3个城市在近40年表现出明显的增温趋势,城区增温明显快于乡村的。各地区增温率的时空变化存在一定差异,与人口密度、工业总产值、用电量及车辆拥有量等经济数据的分布及变化基本一致。沿海城市温州增温率最小,但城乡差异最明显。同样为沿海城市的宁波,由于经济发展地域差别较小,虽表现最明显的增温,但城市热岛效应最弱。3个城市的热岛效应及热岛增温贡献率均存在明显的季节变化:杭州的热岛效应呈春、夏、冬、秋依次减弱的变化规律;温州则呈春、秋、冬、夏依次减弱的变化规律;宁波类似于城市群发展的模式,导致其热岛效应较不明显,以夏季和秋季最强。城市化发展引起的增暖占有较大的比重,杭州和温州年平均气温的增加大约有1/3是由城市化引起的,其中杭州夏季热岛增温贡献率达到2/3以上,温州春、夏季热岛增温贡献率均达到43%左右,宁波城市热岛增温贡献率相对较小,夏季的最大,为20%左右。

Application of Gridded Data in the Research of Urban Climate Changes

To understand the regional differences of urban heating and the effect extent of heat island in Zhejiang province, the climate change trends in Hangzhou, Ningbo and Wenzhou are analyzed. We utilize the method of optimal interpolation to implant temperature data of 62 stations in Zhejiang from 1971 to 2010 into the NCEP monthly average temperature data, in order to reduce the non uniformity of observational data, and get the gridded data spacing of 5 km. The results indicate that apparent warming trend emerged in the last 40 years in the 3 cities, urban warming are significantly faster than rural. The spatial and temporal variation of warming rate in the 3 cities are different, and basically consistent with distribution and changes of population density, industrial output, electricity consumption and vehicle ownership, etc. In the coastal city of Wenzhou, the warming rate is minimal, but the difference between urban and rural areas is the most. The coastal city of Ningbo has the most obvious warming with the weakest heat island effect due to the smaller regional difference of economic development. There are significant seasonal variations for the heat island effect and warming contribution rate of the heat island in the 3 cities. The heat island effect of Hangzhou decreases in the order of spring, summer, winter, autumn, Wenzhou in order of spring, autumn, winter, summer, while the heat island effect of Ningbo is less obvious due to the development pattern of urban agglomeration, is strongest in summer and autumn. Warming caused by urbanization account for a large proportion, about 1/3 of the annual average temperature warming in Hangzhou and Wenzhou is caused by urbanization, more than 2/3 in summer in Hangzhou, up to about 43% in spring and summer in Wenzhou is caused by urbanization, the warming contribution rate of the heat island in Ningbo is relatively small, most in summer, about 20%.