Arctic Aerosol Chemistry and Indirect Climate Effects

人们基本上很好地了解了北极气溶胶的一般季节气候学和化学成分，但有机化合物的贡献还不是很清楚。众所周知，在低纬度地区，有机物在气候强迫中扮演着重要角色。气溶胶对北极气候的直接辐射影响已经确定，但我们对间接影响(通过云微物理相互作用)的了解仍然不完整。特别是，需要进一步了解气溶胶作为云凝结核并增强低层水云反射率的过程，这种现象被称为第一次气溶胶间接效应。提供资金在阿拉斯加州巴罗开展采样计划，以确定全年北极气溶胶中有机的比例，并确定官能团组成、可能的人为来源，并为将北极气溶胶化学成分严格纳入气候变化研究提供基础。首席调查人员将在巴罗部署一台新的短波光谱辐射计，覆盖0.35-2.5微米的波长范围，这将为反演云热力学相、液体/冰水路径和有效粒子半径提供高时间分辨率数据。有了美国能源部位于巴罗的大气辐射测量计划现场的补充数据，他们将能够量化第一个气溶胶间接效应的短波分量，并通过对有机物的新理解，了解液态水路径和有效半径对第一个气溶胶间接效应的贡献。

The general seasonal climatology and chemical composition of Arctic aerosol are basically well understood, but the contribution from organic compounds is not. At lower latitudes, organics are known to play a large role in climate forcing. The direct radiative effects of aerosol on Arctic climate have been identified, but our knowledge of indirect effects (via cloud microphysical interactions) is still incomplete. In particular, further understanding is needed of the processes through which aerosols serve as cloud condensation nuclei and enhance the reflectivity of low-level water clouds, a phenomenon known as the first aerosol indirect effect.Funds are provided to carry out a sampling program at Barrow, Alaska, to determine the fraction of Arctic aerosol that is organic, throughout the year, and identify functional group composition, possible anthropogenic sources, and to provide a basis for rigorous incorporation of Arctic aerosol chemical composition in climate change studies. The principal investigators will deploy a new shortwave spectroradiometer at Barrow, covering the wavelength range 0.35 - 2.5 microns, which will provide high-time-resolution data for retrieval of cloud thermodynamic phase, liquid/ice water path, and effective particle radius. With supplemental data from the U.S. Department of Energy Atmospheric Radiation Measurement Program site at Barrow, they will thus be able to quantify the shortwave component of the first aerosol indirect effect and, through the new understanding they will gain about organics, understand both liquid water path and effective radius contributions to the first aerosol indirect effect.