SULFUR CHEMISTRY IN THE ANTARCTIC TROPOSPHERE EXPERIMENT - AN OVERVIEW OF PROJECT SCATE

In January and February 1994 the Sulfur Chemistry in the Antarctic Tro posphere Experiment (SCATE), a multi-institutional field research proj ect, was conducted at Palmer Station (64 degrees 46'S, 64 degrees 03'W ), Antarctica. In this paper we describe the scientific background and major objectives of SCATE and present an overview of the field measur ement program, the study site, and meteorological conditions prevailin g during the experiment. A specific goal of the SCATE study was to imp rove the current understanding of the chemistry of dimethylsulfide (EM S) in the remote marine atmosphere and its relation to the climate of Antarctica. The SCATE campaign included for the first time measurement s of hydroxyl radical (OH), gas phase sulfuric acid (H2SO4), methanesu lfonic acid (MSA), and nitric oxide (NO) concentrations over Antarctic a. Because of the high time resolution and sensitivity of the correspo nding measurement techniques it was possible to distinguish between me teorological and chemical processes contributing to the distribution o f DMS oxidation products at the study site. Strong vertical exchange p rocesses and long-range transport of marine air masses frequently domi nated the observed concentrations. These processes were governed by in tensive low-pressure cells passing through the Drake Passage and circl ing around the Antarctic coastline.