Tropical UTLS water vapor, clouds, microphysics, and radiation
The focus is to improve our ability to simulate the tropical UTLS region,
which requires detailed understanding of the processes that maintain the
observed distributions of water vapor and clouds, and their links with the
large- and small-scale temperature structure. This includes observing and
simulating the microphysics of cirrus formation and evaporation, and the role
of deep convection and its effects on the radiation and chemical budgets.
Water vapor is a major source of OH, and is thus strongly coupled to chemical
processing and composition in the tropical UTLS.
Two-way stratosphere-troposphere exchange (STE) processes
The overall objective is to better quantify the contribution of STE to the
budgets of ozone and water vapor in the UTLS. There is a need to better
characterize the role of multiple scale dynamical processes, from the
large-scale planetary wave breaking, to synoptic scale baroclinic systems,
and to small scales associated with convection and turbulence. Other issues also
include the effect of gravity wave breaking and turbulent mixing processes near the
extratropical tropopause and the effect of deep convection in redistributing chemical
tracers and aerosols in the UTLS region.
Chemistry that controls the budgets of ozone and radical species in the
UTLS
One focus of this theme is to assess the impact rapid convective upward
transport of near-surface biogenic and anthropogenic emissions or oxidation
products on radical budgets in the UTLS. Gaseous and multiphase processes in
the UTLS control the sources and sinks of radical constituents ( HOx,
NOx, ROx, ClOx, BrOx ), and hence
the processes that control the budget of O3 and removal of many chemical
pollutants.
Composition of aerosol and cloud particles in the UTLS
The processes that control the formation of aerosols and cloud particles in
the UTLS are poorly understood at present. Key topics include the chemical
composition of aerosols and how the composition might influence the generation of cirrus particles. Identification and refined understanding of multiphase
processing of chemical constituents on liquid and ice particles is of
particular importance both for detailed microphysical/chemical models and for
sub-grid scale parameterizations in global models. |
Field Campaigns
Satellite & Modeling
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