台湾海峡及周边海区气溶胶时空分布特征的遥感分析

Remote sensing of the spatio-temporal pattern of aerosol over Taiwan Strait and its adjacent sea areas

首次利用连续3年(2002 ～2004)的MODIS气溶胶卫星遥感资料分析了台湾海峡及周边海区的气溶胶时空分布特征.研究表明,台湾海峡及周边海区气溶胶多年平均光学厚度沿岸呈带状分布且表现出随离岸距离呈指数降低的空间分布特征.各典型海区中,台湾海峡多年平均气溶胶光学厚度最高;其次为东海南部和南海北部,西北太平洋海区的气溶胶光学厚度最低.4个季节的气溶胶光学厚度时空分布特征明显不同,呈现出春季高、冬季略高于秋季、夏季低的特点.春季受我国北方沙尘天气影响,整个海区气溶胶光学厚度高于其它季节,达到0.32;沙尘气溶胶在冬季季风的作用下能够向南跨越东海,最远传输到西北太平洋海区上空,使得该海区的气溶胶光学厚度值达到0.22,明显高于其它季节.夏季则由于东南季风和多降雨天气的影响,陆源污染物向海扩散条件差,气溶胶光学厚度低,仅为0.12.气溶胶类型分布分析表明,近岸海区的气溶胶类型主要以来自陆源的污染和烟尘气溶胶为主,春、秋以及冬季在大气动力的作用下可以输送到较远的海区上空;远岸海区的气溶胶类型则可能主要以海盐气溶胶或沙尘气溶胶(春季)为主;近远海之间海区的气溶胶类型分布则主要以污染气溶胶和海盐气溶胶(或沙尘气溶胶)混合为主.

This paper analyzed the spat/o-temporal pattern of aerosol over Taiwan Strait and its adjacent sea areas using MODIS aerosol data of three consecutive years from 2002 to 2004. It shows that the annually-averaged aerosol optical thickness （AOD） of the study sea area had a zonal pattern distributed along the shore. With the increase of the distance to the shore, the AOD reduced in an exponential decay pattern. Also, among the four typical sea areas, the annually-averaged AOD appears to be highest over the Taiwan Strait, moderate over southern East China Sea and northern South China Sea, and the lowest over northwestern Pacific Ocean. The temporal AOD pattern was substantially different with seasonal change, which was highest in the spring, moderate in the winter and autumn, and lowest in the summer. As affected by the dust from ＇Asian dust, the AOD over the whole study area was obviously higher in the spring than in any other seasons. However the lowest AOD in the summer over the study area, especially in the nearshore area, would be attributed to the influence of the southeast monsoon and rainfall climate. The aerosol type over the inshore sea was mainly the continental pollution and biomass-burning aerosol, which could be transported to the offshore sea by the atmospheric dynamics process such as monsoon in the spring, autumn and winter. While the open ocean may be dominated by the sea-salt or dust-like aerosol, the latter mainly occurred in the spring time.