This project supports measurements of polar organic compounds that will be studied as part of the Calspan cloud/aerosol experiment. The experiment will be conducted during November 1998, using the high-pressure Calspan chamber that is operated by the University of Rochester. The main science objective for the project is to improve understanding of the impact of organic aerosol precursors on the nucleation of new particles, particularly, internally mixed organic-inorganic particles. The instrumentation package requested by the PI is in two parts. In part one, the upgrade of the ion chromatography instrument will permit analysis of dissolved polar organic compounds such as carboxylic and dicarboxylic acids. For part two, the PI requests support to upgrade the thermal evolution apparatus developed by T. Novakov (Lawrence Berkeley Laboratory). The thermal evolution system will be used to quantify the total carbon mass present in the particle and dissolved phases. A graduate student from the University of Washington group will be trained on the thermal analysis system. Thus, the project supports instrumentation that will permit a carbon mass balance to be developed for the Calspan cloud nucleation experiments. The improved quantitative description of carbonaceous compounds in cloud-aerosol processes will provide experimental evidence that is intended to evaluate recent theoretical analyses on the impact of known organic compounds on cloud drops, and thus on climate forcing by aerosol chemical components.
