HR: 09:00h
AN: A51C-04    [PDF]
TI: Preferred Pathways of Tropical Troposphere-to-Stratosphere Transport
AU: * Fueglistaler, S
EM: stefan@atmos.washington.edu
AF: Dept. of Atmospheric Sciences, Univ. of Washington, Seattle, WA 98195 United States
AU: Wernli, H
EM: wernli@iac.umnw.ethz.ch
AF: Inst. for Atmospheric and Climate Science, ETH Zuerich, Hoenggerberg, Zuerich, ZH 8093
AU: Peter, T
EM: thomas.peter@ethz.ch
AF: Inst. for Atmospheric and Climate Science, ETH Zuerich, Hoenggerberg, Zuerich, ZH 8093
AU: Holton, J
EM: holton@atmos.washington.edu
AF: Dept. of Atmospheric Sciences, Univ. of Washington, Seattle, WA 98195 United States
AB: From an analysis of trajectory calculations in the tropical tropopause layer (TTL) based on ECMWF analysis data, we infer typical pathways of tropical troposphere-to-stratosphere transport (TST) for January/February and July/August 2001. It is shown that TST does not occur zonally uniform, but that preferred pathways exist. In particular, the Western Pacific region shows three features which render this region of particular importance for TST. First, its unprecedented convective mass flux into the TTL accounts for about 80% of TST. Second, its tropopause temperatures are lowest, and third, the upper level circulation of the Asian-Australian monsoon ensures that about 70% of TST is transported through this particularly cold region, such that the amount of water entering the stratosphere is found to be largely controlled by these temperatures. In addition to the upper-level circulation of the Asian-Australian Monsoon, the equatorial Easterly Jet and the northern Subtropical Jet are of importance for TST, transporting air from convective outflow over the Western Pacific to the Indian Ocean and Africa, or eastward to South America and Africa, respectively. During ascent in the TTL, air parcels typically travel 5'000-10'000 kilometers in the horizontal before they enter the stratosphere. While we cannot exaplain stratospheric water trends from the analysis of one year, it is conceivable that even minor changes in the pathway of tropical TST could account for changes in stratospheric water.
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 3362 Stratosphere/troposphere interactions
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting