Narragansett, RI. — February 16, 2000–With the help of a $280,000 grant from the National Science Foundation (NSF), University of Rhode Island Graduate School of Oceanography (GSO) atmospheric chemists Brian Heikes and John Merrill of North Kingstown and Julie Snow of Wakefield, along with a team of investigators from other institutions, have begun a series of atmospheric sampling flights and balloon launches to study the origin of ozone in the troposphere, which extends from the earth’s surface to 6-12 miles above the earth. Their research is part of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) experiment. Snow, a GSO doctoral candidate under the supervision of Dr. Heikes, is stationed in Colorado and is operating chemical sampling equipment, developed by Heikes at GSO, onboard a National Center for Atmospheric Research C-130 aircraft, along with thirteen other experimenters plus flight crew onboard. The plane and experimenters will be conducting a bi-weekly series of flights from near Denver, CO, to Churchill, Manitoba, to north of Thule, Greenland, and return. The field mission period extends from February through May 2000 and will capture the photochemical transition from the cold-dark-dry condition of winter to the warm-moist-sunlit condition of summer. It has long been recognized that Northern Hemispheric ozone experiences a maximum in spring; however, it is not known why. Two competing hypotheses are currently being studied: the ozone maximum is the result of photochemistry acting on accumulated pollutants over winter or the ozone maximum is the result of increased the transport of ozone from the stratosphere, 6-30 miles above the earth, down to the troposphere. The TOPSE experiment’s prime science objective is to test the photochemical origin hypothesis under changing meteorological conditions. The NSF-sponsored project consists of a suite of instruments on the aircraft to measure hydrocarbons, nitrogen oxide, sulfur gases, ozone, particles, sunlight, and oxidants. The aircraft measurements are complemented by and complement other ozone data, satellite observations and meteorological observations. Dr. Merrill is coordinating measurements of the vertical profile of ozone using instruments at four sites along the aircraft track. These data will supplement the aircraft measurements, meteorological analyses, and satellite observations of ozone and water vapor. This combination of field observations, remote sensing and modeling efforts is one of the most complete documentation and analysis of ozone, its precursors and photochemistry, and atmospheric dynamics over North America during this time period. A complete description of equipment, people, science plan, and preliminary results can be found on the web at: http://topse.acd.ucar.edu. x-x-x Contact: Lisa Cugini, (401) 874-6642 lcugini@gso.uri.edu Brian Heikes (401) 874-6810 bheikes@gso.uri.edu