中国环保重点城市API指数的时空模态区域分异

从区域空气污染监测、分析、预报研究与综合管理需求出发,利用经验正交函数EOF方法,将全国47个环保重点城市2004年7月1日～2006年6月30日2年逐日API指数(Air Pollution Index)时空分布资料分解为模态特征向量和时间系数,并对模态间差异性进行了Morlet小波分析,研究其频谱差异.在此基础上,建立了全国环保重点城市API指数时空模态区域分异体系.结果表明:以API指数作为评价指标,中国主要城市空气污染存在明显的区域分异,全国47个重点城市可分为10个区域,分别代表不同的污染时空模态.EOF及Morlet小波方法将全国47个环保重点城市API指数的时空分布清晰地表达出来,为空气污染区域分异研究提供了新的方法与思路.由于城市空间分布稀疏,难以涵盖全国所有城市的空气污染信息,因此,区域划分体系合理性有待进一步验证.

Regional spatio-temporal mode differences of air pollution index of key environmental protection cities in China

In order to meet the needs of both scientific research on monitoring, analysis and prediction and integrative management of regional air pollution, API spatio-temporal data from July 1,2004 to June 30, 2006 from 47 key environmental protection cities were analyzed. Data were analyzed by determining the eigenvector and temporal modulus with the EOF method. The differences between each mode were analyzed by the Morlet Wavelet method and the differences between each set of spectra were studied. The results showed that the regional differences among major Chinese environmental protection cities was significant based on the API as the assessment index, The 47 key cities may be divided into 10 areas, which represent different special pollution spatio-temporal modes, The analysis by the EOF and Morlet Wavelet methods reflected the spatio-temporal differences distinctly. However, the correspondence of the results with real conditions should be further validated because of the sparse distribution of the 47 cities for which API data is available, These cannot represent the air pollution characteristics of all cities in China.