基于MAX-DOAS的乌鲁木齐市NO2时空变化

为研究乌鲁木齐市NO2污染状况，了解其时空分布特征及其影响因素，基于多轴差分吸收光谱技术（MAX-DOAS），利用2014年4月—2015年12月3个监测点和多次车载移动观测的数据，反演了乌鲁木齐对流层NO2垂直柱浓度（VCD），并且结合气象和地形等因素进行了分析。结果表明：NO2 VCD由高到低的季节依次是冬季、春季、秋季和夏季，均值为10.84、7.78、5.98和3.56×1015 molec·cm-2；由高到低的监测站依次是城区站、工业区站和郊区站，年均值为9.52、8.44和5.58×1015 molec·cm-2；日变化上春冬两季呈U型，夏秋两季呈双峰型；NO2空间分布由南到北呈明显的"两头低中间高"，高值通常出现在市区高架桥附近；乌鲁木齐NO2 VCD与气象因子温度、风速、相对湿度、日照时数都有较好的相关性；乌鲁木齐夏季盛行西北风，顺势于地形利于市区污染物传输出去，冬季盛行东北风，而东面有博格达山阻挡致使风速较低，污染物滞留堆积浓度高。

Spatiotemporal of NO2 in Urumqi based on MAX-DOAS

To illuminate the NO2 pollution situation in Urumqi, and to investigate spatiotemporal characteristics of NO2 and also correlation between NO2 and other reasons, based on the Multi axis differential optical absorption spectroscopy (MAS-DOAS) technology, by utilizing the data of the three monitoring sites and the vehicle mounted mobile observation from April 2014 to March 2015, in the study the vertical column densities (VCD) of NO2 in the troposphere of Urumqi was inverted, and also analyzed by combining with the factors of meteorology and topography. The result showed that:the sequence of different seasons with the NO2 VCD from high to low level are respectively the winter, spring, autumn and summer, with the average values in 10.84、7.78、5.98 and 3.56×1015 molec·cm-2 respectively. For the sequence of observation stations with the observed value from high to low level are respectively the urban area station, industrial area station and farm area station, with the annual average values in 9.52, 8.44 and 5.58×1015 molec·cm-2. The daily variation showed the U shape in both the winter and spring, and the bimodal shape in both the summer and autumn; its distribution from the south to the north showed obviously the shape of "higher on the two ends but lower on the central part", the peak value usually appeared at the area near the overpass in urban district; the NO2 VCD in Urumqi has had the quite good correlationship with those meteorologic factors such as the temperature, wind speed, relative humidity and sunshine duration. In summer the northwest wind shall prevail in Urumqi, along with the trend of topography, it shall be beneficial for the transmission of urban pollutant, in winter the northeast wind shall prevail in Urumqi, with the obstruction of Mount Bogda at the east side resulting in low wind speed, high concentration of pollutant retention.