Arctic Aerosol Chemistry and Indirect Climate Effects

一般的季节性气候学和北极气溶胶的化学成分基本上已经被很好地了解了，但有机化合物的贡献还不清楚。在低纬度地区，已知有机物在气候强迫中起着重要作用。气溶胶对北极气候的直接辐射效应已经确定，但我们对间接效应（通过云微物理相互作用）的认识仍然不完整。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。拨款用于在阿拉斯加巴罗进行取样计划，以确定北极全年有机气溶胶的比例，确定功能群组成，可能的人为来源，并为在气候变化研究中严格纳入北极气溶胶化学组成提供基础。主要研究人员将在Barrow部署一个新的短波光谱辐射计，波长范围为0.35 - 2.5微米，它将为云热力学相位、液体/冰水路径和有效粒子半径的检索提供高时间分辨率的数据。有了巴罗美国能源部大气辐射测量计划站点的补充数据，他们将能够量化第一次气溶胶间接效应的短波成分，并且通过对有机物的新了解，他们将了解液态水路径和有效半径对第一次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.