南宁地区气溶胶光学特性的季节特征

Seasonal Characteristics of Aerosol Optical Properties over Nanning

运用CE318太阳光度计对南宁地区气溶胶光学特性的季节变化特征进行了观测.反演得到气溶胶光学厚度（AOD500nm）季节分布：冬季（0.98）〉春季（0.77）〉秋季（0.75）〉夏季（0.47）;ngstrm波长指数从大到小依次为冬季（1.33）〉夏季（1.30）〉秋季（1.15）〉春季（0.95）;气溶胶粗模态上的体积数浓度：春季〉冬季〉秋季〉夏季,对应细模态的体积数浓度由大到小依次为：冬季〉秋季〉夏季〉春季;单次散射反照比（以440nm为例）在夏季（0.98）最高,散射光学厚度在冬季有极大值.由微脉冲激光雷达得到平均垂直消光系数大小依次为：冬季（0.15）〉秋季（0.14）〉春季（0.13）〉夏季（0.08）.根据地基观测结果分析了南宁地区气溶胶的季节类型,存在冬季（12、1、2月）的霾/混合气溶胶、春季（3-5月）的沙尘气溶胶、初夏（6月）的生物质气溶胶、夏季的背景气溶胶,以及秋季城市/工业气溶胶;进一步对比分析了地基、卫星（MODIS）遥感反演的AOD参数（137个样本）,75%样本在误差范围内,MODIS总体上呈现污染天低估的特征（〉20%）;干净天则多为高估结果,最高的误差频率出现在0-0.1区间.

Utilizing CE318 sun-photometer, a consecutive observation was conducted in Nanning to study the seasonal characteristics of aerosol optical property. Aerosol optical depth（AOD） at 500 nm was found in the order.. winter（0.98）, spring （0.77）, autumn （0.75） and summer （0.47）. AngstrOm exponent presented the order： winter（ 1.33 ）, summer （1.30）, autumn （1.15）, spring （0.95）. The result showed that aerosol volume concentration of coarse mode： spring〉winter〉autumn〉summer, while fine mode： winter〉autumn〉summer〉 spring. Single scattering albedo（SSA） at 440 nm was found largest in summer（0. 98） while SSAX AOD in winter was larger than values in other seasons. Based on micro-pulse lidar（MPL）, columnar extinction ratio was inversed in the order of winter（0.15）, autumn（0.14）, spring（0.13）, summer（0. 08）. Different aerosol types in Nanning were analyzed from ground-based observation： haze/mixed, dust, biomass smoke, clean and urban/industrial were figured out in winter（December, January and February）, spring（March, April and May）, early summer（June）, summer and autumn, respectively. Validation of AODs between ground-based （CE318） and satellite based （moderate-resolution imaging spectra-radiometer, MODIS） with 137 samples, among which 75% of results were satisfying. The deviation occurred in severe pollution （error〉 20 %） while some over-estimations （0 - 0.1） were found in clean days.