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Stratosphere-Troposphere Exchange Project Project Description
This project seeks to determine how trace gases are exchanged between the lower atmosphere (the troposphere) and the upper atmosphere where the ozone layer is located (the stratosphere). This is critical to assessing the effects of natural and human-induced surface emissions on the potential for ozone depletion and global warming. To develop an understanding of transport processes in the lower stratosphere and at its lower boundary, specific scientific questions are addressed: (1) how does air move upward into the stratosphere in the tropics? (2) can these processes of upward movement explain the extreme dryness of the stratosphere? (3) what is the nature and importance of wave motions produced by rapidly rising air in the tropics? and (4) how does air move between the tropics and midlatitudes in the stratosphere? The approach involves the analysis of ER-2 measurements from data obtained from the Stratosphere-Troposphere Exchange Project (STEP), with additional aircraft data from the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratosphere Expedition. So far, the data from STEP have (1) provided explanations for how tropical clouds move air from the troposphere to the stratosphere; (2) shown that the tops of these clouds are dry enough to account for low stratospheric humidities; (3) measured wavelike structures produced above tropical clouds; and (4) shown that other wavelike structures can move stratospheric air from the tropics to the midlatitudes. For more information, link to "http://geo.arc.nasa.gov/sge/jskiles/fliers/all_flier_prose/ strattropexchange_pfister/strattropexc_pfister.html" [Summary provided by NASA] |
