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THE EXTRATROPICAL UPPER TROPOSPHERE AND LOWER STRATOSPHERE
Author(s) -
Gettelman A.,
Hoor P.,
Pan L. L.,
Randel W. J.,
Hegglin M. I.,
Birner T.
Publication year - 2011
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/2011rg000355
Subject(s) - stratosphere , troposphere , tropopause , extratropical cyclone , atmospheric sciences , environmental science , radiative transfer , trace gas , climatology , context (archaeology) , geology , physics , paleontology , quantum mechanics
The extratropical upper troposphere and lower stratosphere (Ex‐UTLS) is a transition region between the stratosphere and the troposphere. The Ex‐UTLS includes the tropopause, a strong static stability gradient and dynamic barrier to transport. The barrier is reflected in tracer profiles. This region exhibits complex dynamical, radiative, and chemical characteristics that place stringent spatial and temporal requirements on observing and modeling systems. The Ex‐UTLS couples the stratosphere to the troposphere through chemical constituent transport (of, e.g., ozone), by dynamically linking the stratospheric circulation with tropospheric wave patterns, and via radiative processes tied to optically thick clouds and clear‐sky gradients of radiatively active gases. A comprehensive picture of the Ex‐UTLS is presented that brings together different definitions of the tropopause, focusing on observed dynamical and chemical structure and their coupling. This integral view recognizes that thermal gradients and dynamic barriers are necessarily linked, that these barriers inhibit mixing and give rise to specific trace gas distributions, and that there are radiative feedbacks that help maintain this structure. The impacts of 21st century anthropogenic changes to the atmosphere due to ozone recovery and climate change will be felt in the Ex‐UTLS, and recent simulations of these effects are summarized and placed in context.