Chapter 7. Atmospheric and Oceanic Research in CIRES:
Atmospheric Physics, Cryospheric and Polar Processes,and Climate Dynamics
Climate Processes: Physics of the Atmosphere-Ocean System
While the Climate Group was organizing and concentrating on the assembly
of large data sets to address the El Niño/La Niña problem, it became
clear that understanding various physical processes also needed to
be part of the overall research effort. The oceanographic community, following
the seminal work of D. Moore and J. McCreary on the behavior
of equatorial waves and their role in El Niño, had developed an elegant
description of the phenomenon as an oceanic response to changing
atmospheric forcing. This led naturally to questions about how the ocean
and atmosphere are coupled and what changes the atmosphere. To investigate
this, EPOCS, in essence, went airborne.
One aspect of the air-sea coupling issue was tackled at CIRES in a
combined modeling/observational program that brought together Eric
Kraus, Howard Hanson (both from CIRES' sister institute in Miami, the
Cooperative Institute for Marine and Atmospheric Studies), S.J.S.
Khalsa, and colleagues in the NOAA/ERLs in Boulder, notably Vernon
Derr and Gary Greenhut. This work, originally funded by EPOCS, grew
and eventually became part of the Office of Naval Research Marine
Meteorology Program, including the Frontal Air-Sea Interaction Experiment
(FASINEX), and the NASA First ISCCP (International Satellite Cloud
Climatology Project) Regional Experiment, FIRE. A particularly important
finding was that the coupling of the ocean to the free atmosphere was
accomplished in the planetary boundary by turbulent elements (in the
form of rising and descending plumes) that account for much of the
transport between the media. This result, obtained via measurements
from NOAA research aircraft, led to elucidation of the role of marine
stratus and stratocumulus clouds, and especially their instability
processes, in the ocean's heat budget in FIRE.
On larger spatial scales, the problem of changes in the atmosphere was
also a topic of interest at CIRES. The assembly of COADS provided a rich
marine data set on monthly time scales, but it took analysis of individual
weather maps by Richard Keen, Ellen Steiner, Richard Grotjean, and colleagues
led by Colin Ramage to reveal that synpotic-scale disturbances in
the tropics ("westerly wind bursts") changed surface wind stress patterns in
ways that could initiate an El Niño event. This finding also shifted the focus
of ENSO research from the Eastern Pacific westward, where these changes
in atmospheric flow occur. It also played a role in the recognition that
ENSO is a global phenomenon in the atmosphere that couples to the tropical
oceans, which recognition subsequently spawned the TOGA (Tropical
Ocean/Global Atmosphere) research program.
The westward shift in focus took a quantum leap in the early 1990s,
when Peter Webster joined CU to direct the newly fledged Program in
Atmospheric and Oceanic Sciences and became a CIRES fellow. His leadership
in TOGA/COARE (Coupled Ocean-Atmosphere Response Experiment),
in which the behavior of the tropical warm pool in the far western
Pacific is the subject of both observational and modeling efforts, continues
to the present.
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