气溶胶与气候

Aerosol in Relation to Climate Change

气溶胶粒子对气候系统的辐射平衡有重要影响。气溶胶对气候的影响可分为两大方面 ,即直接影响和间接影响。直接影响指大气中的气溶胶粒子吸收和散射太阳辐射和地面射出长波辐射从而影响地 -气辐射收支。模式计算表明 ,人类活动引起大气气溶胶增加倾向于使地球表面降温 ,工业化以来 ,气溶胶增加引起的地面变冷趋势可部分抵销温室气体增加引起的地表温度上升。气溶胶对气候的间接影响是指气溶胶浓度变化会影响云的形成 ,而云的变化反过来对气候有巨大影响 ,这方面至今还没有定量结果。

Anthropogenic aerosol may account for a large part of the discrepancy between observed climate change over the industrial era and model calculations based on anthropogenic greenhouse gases only Aerosols in general, and anthropogenic aerosols in particular have the significant potential to influence the radiative transfer through the atmosphere and the atmospheric water cycle, thus influence the Earth′s climate directly and indirectly Although some aerosol particles may absorb thermal radiation and hence have greenhouse effect, the major influence of aerosols is scattering the incoming solar radiation, thereby increasing the planetary albedo and cooling the Earth′s surface Anthropogenic aerosols acting as cloud condensation nuclei are believed to increase the number concentration of cloud droplets, and thereby influence the radiation balance Model calculations show that the increase of anthropogenic aerosols may partly compensate the warming effect of the increasing greenhouse gases However, climate effects of aerosol are critically dependent on the size distribution, rather than on the mass loading, and the geographical distribution, rather than on the regional or global mean values These make the climate assessment more difficult In fact, the climate effects of aerosol present the largest source of uncertainty in calculating the anthropogenic climate forcing over the industrial period