合肥地区气溶胶光学特性的地基观测研究

Ground-based Remote Sensing of Aerosol Optical Properties Over Hefei Region

利用自主研制的DTF-5型太阳辐射计观测舍肥地区2008年10月～2010年5月的太阳直接辐射消光，反演合肥地区气溶胶光学厚度、Angstrom参数和沙尘天气过程中的粒子谱分布，并对结果进行分析。结果表明：合肥地区气溶胶光学厚度季节变化除气候因素外，受人为因素影响明显，季节变化规律复杂。总体上秋季较小，冬春季节持续增大，夏季较平稳。而Angstrom参数与气溶胶光学厚度大致呈反相关，秋冬上升，春季骤降．夏季平稳值较大。气溶胶光学厚度日变化大致可分为4种类型：日变化相对稳定；整体呈上升趋势；整体呈下降趋势；一日内出现一到多个峰值。其中第四种类型出现几率最大。沙尘天气过程中，气溶胶光学厚度和Angstrom参数分别呈现出“谷-峰-谷”、“峰-谷-峰”的变化规律，其中Angstrom参数在沙尘影响严重时甚至出现负值。半径为0．2～1．0μm的大粒子和大于1．0μm的巨粒子浓度在沙尘天气过程中大幅增加。

A self-made ground-based sun-photometer was used to measure the direct solar irradiances, from October 2008 to May 2010 over Hefei, China. The aerosol optical depth （AOD）, Angstrom parameter （a）, and the spectrum distribution of aerosol particles during the strong dust storms were retrieved. The seasonal variation of AOD was complex, it＇s related to not only the seasonal variation of the synoptic weather pattern of Hefei, but also the human activities closely. In a word, the AOD was minimum in autumn, increase during winter and spring, and kept intermediate in summer. The variation in α was opposite to AOD, which increased in autumn and winter, decreased sharply in spring, and kept moderate value in summer. There were four diurnal variability patterns of AOD that AOD remained almost constant; AOD gradually increased over the day; AOD showed a general trend of decrease; AOD showed one or more peak value during the day, which occured most frequently. The variation of AOD indicated an obvious ＂valley-peak-valley＂ pattern during the strong dust storm, while α demonstrates a ＂peak-valley-peak＂ pattern. The aerosol size distributions indicated that more large particles with radius of 0.2-1.0 μm and 〉1.0μm were injected into the atmosphere during the dust outbreak episode.