Climate Process Team on Gravity Current
Entrainment
The CPT (Climate Process Team)
is a new paradigm established by the U.S. CLIVAR program for linking
process-oriented research and coupled climate model development.
A CPT is a group of scientists funded by the National Science Foundation
and the National Oceanic and Atmospheric Administration to:
- speed the transfer of theoretical and process-model understanding
into improved treatment of processes in climate model systems,
- identify
process study activities necessary to further refine climate model
fidelity, and
- develop sustained observational requirements for climate
model systems.
Overview
The CPT on Gravity Current Entrainment aims to develop parameterizations
of dense gravity currents in the ocean for inclusion in climate models.
Dense water formed through cooling or evaporation in marginal seas
(e.g. Greenland-Iceland-Norwegian sea, Mediterranean Sea) or coastal
shelves (e.g. Antarctic shelf) enters the general ocean circulation
by flowing over topographic features including narrow channels (e.g.
Denmark Straits, Gibraltar Straits) and down the continental slope.
As the dense water descends it entrains ambient water, which mixes
with the dense water, modifying the tracer properties and volume
of the dense water. Present climate models do not have sufficient
resolution to capture the small scale processes responsible for entrainment,
and hence cannot correctly simulate the properties of the dense water
masses which result, some of which (e.g. North Atlantic Deep Water,
Mediterranean Overflow water, Antarctic Bottom Water) play very important
roles in the large-scale ocean circulation. The goal of the CPT on
Gravity Current Entrainment is to use knowledge gained from recent
observations of dense overflows and laboratory and numerical process
studies to improve the representation of dense gravity currents and
their entrainment in climate models, thereby enhancing their ability
to predict current and future climate.
Objectives
(a) Closely examine entrainment in recent observations, especially
those of Denmark Straits Overflow, Faroe Bank Channel, Mediterranean
Outflow, Red Sea Overflow and Antarctic slope overflows, as well
as laboratory and numerical process studies.
(b) Use this knowledge to develop new and enhanced parameterizations
of entrainment.
(c) Implement and test the new parameterizations in Ocean General
Circulation models. |
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