1961-2010年安徽省大气环境容量系数变化特征分析

基于1961-2010年安徽省气象台站的定时观测资料，采用国标法计算安徽省近50年大气稳定度、混合层厚度和大气环境容量系数，并结合合肥市空气质量逐日观测数据初步分析了大气环境容量系数对空气质量的影响。结果表明：安徽省大气稳定度以中性类居多，稳定类其次；近50年来，中性类稳定度呈明显下降趋势，不稳定类和稳定类呈显著上升；不稳定类和稳定类有明显的季节差异，中性类不明显。年平均混合层厚度显著下降；春季混合层厚度在2000年左右发生转折，夏、秋、冬三季下降趋势显著；春、夏季混合层厚度高于秋、冬季，冬季最低，春季最高。安徽省大气环境容量系数以沿淮中部、大别山区南部和沿江中西部最大，淮北大部、大别山区北部和江南南部最小，各地均呈现一致的显著下降趋势，并具有明显的年代际变化特征。年内大气环境容量系数呈"双峰型"分布，秋、冬季为低值时段，大气对污染物容纳能力较差，不利于扩散和清除，空气质量较差。总的来看，1961-2010年安徽省大气稳定度显著增加，混合层厚度较明显下降、风速快速减弱是全省大气环境容量系数变小、大气自净能力减弱的最主要原因。

Variation Characteristics of the Atmospheric Environmental Capacity Coefficient in Anhui Province During 1961-2010

Atmospheric stability, mixed layer thickness and the atmospheric environmental capacity coefficient are calculated by using the fixed timing observation data during 1961-2010 in Anhui province. The air quality index is also involved here to explore the relationship between atmospheric environmental capacity and air quality. Results indicated that neutral stability accounts for the highest proportion and stability one comes second. Neutral stability presented a significantly decreasing trends while the stability and instability showed increasing trends. Seasonal difference were existed for instability and stability, but not for neutral instability. The annual mean atmospheric mixed layer thickness (AMLT) exhibited a significantly declining trend. Common characteristics were also found with seasonal mean AMLT in summer, autumn, and winter, while the spring mean AMLT demonstrated an abrupt change in the 2000. AMLT in spring and summer were generally higher than that in autumn and winter. The atmospheric environmental capacity coefficient showed obvious spatial differences with high values in the middle reaches of the Huaihe River, southern Dabie Mountain and midwest area of the region along the Yangtze River, which comparatively showed low values in most areas north to Huaihe River, northern Dabie Moutain and south area to the south of the lower reaches of the Yangtze River. There was a remarkably declining trend with the atmospheric environmental capacity coefficient all over Anhui province, which demonstrated prominent interdecadal variation characteristics. Seasonal atmospheric environmental capacity coefficient presented a "double peak value" pattern and reached its minimum mostly in autumn and winter, which went against the diffusion, transmission and elimination of the air pollutants, thus the air quality might get worse with limited capacity. Generally, significantly increasing trend for stability, as well as declining trend with AMLT and rapidly decreasing trend for wind speed might be the possible reasons for the continuing decreasing trend with atmospheric environmental capacity coefficient and corresponding self-purification capability in Anhui province.