中国中东部秋季PM10时空变化及其与日气温的关系

利用2000-2010年秋季中国中东部83个重点城市的PM10浓度数据以及其中63个城市的逐日气象资料,分析了PM10浓度的时空变化以及晴空条件下PM10浓度与日气温之间的关系,讨论了不同云量条件下二者关系的稳定性以及辐射的相应变化.结果表明:(1)近11年来,秋季PM10浓度呈现下降趋势,全部天气条件下和晴空条件下的线性趋势值分别为-2.87 μg·m-3/年、-4.92 μg·m-3/年;空间分布上,中国中东部重点城市的秋季PM10浓度普遍下降,其中华北地区的下降最快最显著.(2)秋季PM10浓度与日气温的波动之间存在显著相关,定量统计表明:当PM10浓度偏高10 μg·m-3时,日最高气温、日最低气温和日平均气温分别偏低0.15℃、0.14℃和0.16℃,同时气温日较差减小0.01 ℃.(3)秋季日气温的上述变化可能主要与气溶胶的直接效应有关.PM10增多会造成地面总辐射和地表净辐射的显著减少,进而造成日最高气温、日平均气温的显著下降;同时,PM10增多对近地面的影响总体上是致冷效果.

Spatiotemporal Variation of PM10 Concentration and Its Relationship with Autumn Daily Temperature over Central and Eastern China

Based on the autumn data of daily PM10 concentrations in 83 key cities and daily temperature,precipitation and total cloud cover in 63 key cities over Central and Eastern China from 2000 to 2010,the spatiotemporal distribution and variation of PM10 concentration were studied.The results were as follows.(1) During the past 11 years,the averaged PM10 concentration in autumn has showed a relatively steady downward trend on both all days and clear days,with a linear trend of-2.87 μg.m-3/yr and-4.92 μg.m-3/yr respectively.As to spatial variation,PM10 concentrations in most cities of Central and Eastern China have decreased significantly.(2) There were significant correlations between PM10 concentrations and daily temperatures in autumn.The quantitative statistics showed that as PM10 concentration increased by each 10 μg.m-3,the daily maximum temperature,daily minimum temperature,daily mean temperature and diurnal temperature range would decrease by 0.15 o C,0.14 oC,0.16 oC and 0.01 oC respectively.(3) The changes of daily temperature in autumn may be caused mainly by direct effect of PM10.When PM10 concentration increased,the surface solar radiation and surface net radiation would decrease significantly,and hence,the daily maximum temperature and daily mean temperature would decrease significantly.