Transport in the Stratosphere at Low Latitudes and the Quasi-Biennial Oscillation

点击翻译按钮获取中文摘要

9634394 O'Sullivan Transport from the tropics to the extratropics in the stratosphere occurs mainly by isentropic advection and stirring into the active surf zone of the winter hemisphere midlatitudes. The transport couples two regions of differing constituent concentrations: the (upwelling) tropical region and the (mostly downwelling) extratropics. Besides varying seasonally, such transport is affected by the quasi-biennial oscillation (QBO). The principal objective of this research is to investigate the manner in which the QBO affects transport by (a) its mean meridional circulations, (b) its modulation of Rossby wave propagation and breaking at the low latitudes, (c) its modulation of the extratropical Rossby wave activity and surf zone mixing, and consequently (d) its modulation of the global Brewer-Dobson residual circulation strength during the winter season. The study will rely primarily on numerical simulations with a three-dimensional model of the middle atmosphere and a tracer transport model. The results will be compared with other simulations and satellite observations of the middle atmosphere. This work will also provide estimates of stratospheric transport rates form the tropics to the extratropics for each season and for different phases of the QBO as a function of height. Dr. O'Sullivan is a young scientist who has established an excellent reputation in the middle atmosphere research community. His work is contributes not only to better understanding of stratospheric dynamics, but also provides critical information on processes that affect the photochemical processes of the region as well. ***