2011 - Cooperative Institute for Research in Environmental Sciences ...

Baylor Fox-Kemper
Improving Subgridscale Physics
in Ocean Climate Models
FUNDING: NATIONAL SCIENCE FOUNDATION, NASA,
NATIONAL CENTER FOR ATMOSPHERIC RESEARCH
My research group
focuses largely on the representation
of mesoscale
(100 km), submesoscale
(1-10 km) and Langmuirscale
(100 m) mixing
processes in global climate
models. The group is
improving the representation
of these processes
in climate models and
has demonstrated some
impacts of properly representing
them on global
climate simulations.
On April 20, 2010, the
explosion of
the Deepwater
Horizon oil
platform and
subsequent oil leakage have provided images of
many near-surface mixing processes in action. The
shape of the spilled oil as it spreads and is stirred
by mesoscale and submesoscale eddies and the
formation of windrows between the Langmuir
cells are disturbing examples of oceanic stirring at
different scales. Understanding where and why
these Langmuir windrows occur has been a big
part of my group’s effort this year, with support
from NASA and the National Science Foundation
(NSF).
On larger scales, submesoscale eddies stir the
upper ocean. These eddies form from thin currents
called fronts that occur in the upper ocean. These
fronts can result from flow around obstacles, uneven
wind or cooling, or even stretching by larger
eddies. The image at right shows a false-color
satellite image showing some of the stirring by
submesoscale features. The false colors accentuate
the differences between slightly different colors of
water due to biology or water properties.
The submesoscale parameterization developed
by my group is being used in many of the models
36 CIRES Annual Report 2011
presently simulating future climate for the upcoming Intergovernmental
Panel on Climate Change Fifth Assessment
Report (IPCC AR5), due in 2013.
A new set of simulations has begun this year. It is a series
of simulations designed to understand the interactions
between Langmuirscale and submesoscale features. These
simulations are expensive, requiring months of calculation
on thousands of processors at a time. Through NSF’s
TeraGrid system and the National Center for Atmospheric
Research’s supercomputing center, these simulations
will give us our first indications of how these scales may
interact. An upcoming Natural Environment Research
Council observational campaign, called OSMOSIS (Ocean
Surface Mixing, Ocean Sub-nesoscale Interaction Study),
will provide direct observations of the same phenomena in
the real world.
False-color satellite image of submesoscale fronts and eddies in the Tasman Sea.