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Assessing Meridional Overturning Circulation
Variability: Implications for Rapid Climate Change
The objective of this near-term priority is improved understanding of the mechanisms
behind fluctuations of the MOC, which will lead to new capabilities for monitoring and
making predictions of MOC changes. These predictive capabilities will help identify the
impacts of MOC changes on the ocean, climate, extreme weather events, regional sealevel
changes, ecosystems, and carbon budgets.
Approach
Given current limited understanding of the MOC, describing the MOC, its variability,
and critical process, and the ability to model these will be an early and ongoing emphasis
of the program. Enhanced understanding of the MOC system, including its processes
and fluctuations, will be gained through the analysis of existing data sets. This expanded
understanding will provide the foundation for the design and implementation of a comprehensive
MOC observation and monitoring program. In parallel, new forecasting capabilities
will be developed by improving ocean models, coupled models, and ocean analyses
for their initialization. Finally, interdisciplinary research and modeling studies will be
required to characterize the impacts and feedbacks of changes in the MOC on ecosystems,
carbon budgets, and regional climate. Initial federal implementation is derived from
the work of three agencies and has many linkages with CCSP. Agency contributions to
address this priority include:
• NASA—Use current and future ocean measurements from satellites to assess processes
responsible for MOC variability and to improve ocean models through
advanced ocean-state estimation. Refine ocean-state estimates spanning the past
50 years, incorporating all available in situ and remotely sensed observations. Use
modeling studies to assess impacts of MOC changes on sea-level changes and high
latitudes.
• NOAA—Conduct modeling experiments on the origins of MOC variability leading
to improved understanding of the relative roles of wind and thermohaline forcing.
Test models and theories against climate data sets and implements improved models
for MOC-related studies.
• NSF—Conduct relevant ocean-process studies in the Atlantic and sub-Arctic
Oceans to improve ocean-model parameterizations, and performs MOC analysis
and modeling studies. Support historical MOC reconstructions and improved dataassimilation
systems; initiate modeling studies of the impacts of MOC changes on
North Atlantic storminess, ecosystems, and ocean carbon uptake.
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