气象条件和污染物排放对兰州市冬季空气质量的影响

Impact of Meteorological Conditions and Pollutant Emissions on Winter Air Quality in Lanzhou

利用人工神经网络(ANN)技术,基于气象条件、污染物排放变化和污染物浓度资料构建污染物浓度统计模型,在此基础上分析气象条件和污染物排放源排放变化对污染物浓度逐日变化和年际变化的影响。研究结果发现基于ANN建立的大气污染统计预报模型模拟NO_2浓度准确性较高,其次为SO2,PM10浓度准确性较低。ANN的输入参数更适合NO_2的模拟,SO2和PM10浓度的影响因子较为复杂。气象条件变化是NO_2浓度逐日变化的主要影响因子,污染物排放量变化是NO_2浓度年际变化的主要影响因子。因子分离法计算得到的气象条件、污染物排放及两者相互作用对NO_2浓度逐日变化的贡献率分别是57.9%、24.5%和17.6%,对NO_2浓度年际变化的贡献率分别是13.7%、73.3%和13%。

To quantify the impact of meteorological conditions and pollutant emissions on air quality in Lanzhou,this paper developed an artificial neural network（ ANN） model to forecast winter daily average pollutant concentrations in Lanzhou based on six years meteorology and pollutant concentration data,and the model was used to investigate the influence of meteorological conditions and pollutant emissions on daily and interannual variations of pollutant concentrations via sensitivity test. The high resolution meteorological data in Lanzhou was acquired from the Weather Research and Forecasting（ WRF） model. The results showed that ANN model had a good performance to NO2,followed by SO2 and PM10. The statistical performance indicated that the input data selected in this study may be more suitable for NO2. The relative lowstatics for SO2 and PM10were caused by the complex emissions for SO2（ elevated point sources） and PM10（ local dust）. With good performance,the NO2 was selected to analysis the influence of meteorological conditions and pollutant emissions. The change of meteorological conditions is the main factor causing the daily variation of NO2 concentration,while pollutant emissions change is mainly responsible for the interannual variation of NO2 concentration. Utilizing factor separation method,the contribution of meteorological conditions,pollutant emissions and interactions to NO2 concentration daily variation are 57. 9%,24. 5% and17. 6%,respectively,and 13. 7%,73. 3% and 13% for NO2 concentration interannual variation. The simple assumption of emission information has an adverse impact on the results,and the improvement of emission information will be needed in the further research.