U.S.-Japan and U.S.-France Cooperative Research: Determination of Aerosol Composition and Concentration from ILAS-II Infared Solar Occultation Measurements

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

9981542 Eldering This award supports a three-year collaborative research project between Professor Annmarie Eldering of the University of California in Los Angeles and Dr. Yasuhiro Sasano of the National Institute for Environmental Studies in Tsukuba, Japan. Collaboration also involves researchers at CNES (French Space Agency) and CNRS (French National Center for Scientific Research. The researchers will be undertaking a study of the determination of aerosol composition and concentration from ILAS-11 infrared solar occultation measurements. An important yet poorly understood heterogeneous chemistry problem is the role of polar stratospheric clouds (PSCs) in ozone destruction in the polar stratosphere. Laboratory studies and in situ observations show that PSCs act as catalysts, transforming chlorine containing compounds into reactive forms, which destroy ozone. New methods are needed to measure the composition and concentration of aerosols on a global basis and satellite measurements have a great untapped potential for this goal. In the fall of 2000 ADEOS-11 will be launched by the Japanese Space Development Agency and this satellite will include ILAS-11, an infrared limb sounding instrument. This instrument will provide a unique data set of limb observations through PSCs. The specific objectives of the research are: 1) compare spherical and nonspherical models for nitric acid trihydrate and dihydrate extinction to the aerosol extinction measured with ILAS-11 and examine the composition of polar stratospheric clouds from the IR spectra; 2) use nonlinear least squares methods to retrieve aerosol slant columns of polar stratospheric clouds, ice, and sulfuric acid; and 3) attempt to develop vertical profiles of aerosols, ice and PSCs from slant columns. The project brings together the efforts of two laboratories that have complementary expertise and research capabilities. Knowledge of the composition and global distribution of aerosols is important for understanding climate change and a number of atmospheric chemistry problems. This research could have a significant impact on a broad range of atmospheric science areas and should greatly increase our understanding of aerosols. The project advances international human resources through the participation of postdocs and a graduate student. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation. Results of the research will be published in international scientific journals and will also be presented at scientific meetings in the U.S. and abroad.