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Ocean Surface Topography from Space
SCIENCE
Processes Connecting Coastal To Basin-Scale Ocean Circulation


Author:

Paul Strub - (Oregon State University)



Abstract:
Variability in the circulation of the coastal ocean is controlled by a combination of local and distant forcing. The objectives of the work proposed here are:
  1. to advance the use of altimeter data for coastal research;
  2. to quantify the variability in coastal circulation in several prototypical coastal ocean regions over a wide range of time scales; and
  3. to understand and quantify the processes that control that variability, with special emphasis on the processes that connect coastal regions to the large-scale ocean circulation.
The prototype regions are eastern boundary upwelling regions with narrow shelves and broad-shelved coastal regions inshore of western boundary currents. Our analyses will make use of our experience and ongoing projects in analyzing satellite data and numerical model fields along the eastern and western boundaries of the Pacific and Atlantic Oceans. Rather than focusing on the regions themselves, however, our primary research area will emphasize the physical processes that control variability in coastal circulation, using these regions to provide specific examples of the more general processes. The methods used include altimetric analyses that will quantify the physical variability and the statistical connections between coastal and large-scale regions. Additional statistical relationships to local and distant winds, SST and phytoplankton pigment concentrations will be explored using multiple (U.S. and International) satellite sensors. To understand the dynamics of the processes, nested numerical models of these regions will be used, with both realistic and idealized configurations. Results from these studies will also be used to examine new regions of interest in the Indian Ocean. This will be the thesis work of a graduate student from India, Laxmikant Dhage, who is presently enrolled in the Physical Oceanography program at OSU/CEOAS. Mr. Dhage will investigate the extent to which similar processes are at work along India s eastern and western coasts.

Our investigation will contribute to the accomplishment of seven of the eight solicitation objectives as follows:

  • It will use the ~20-year record of multiple altimeter time series, compared to other satellite data (SST, wind and chlorophyll-a pigment concentrations) and nested model fields to explore basic physical oceanographic processes, extending the work through models to examine climate variability; it will improve the retrieval of altimeter data in coastal regions, which will improve the use of altimeter data in operational applications.
  • It will use the higher-resolution data sets combining all available altimeters to examine coastal jets and eddies associated with both western and eastern boundary currents.
  • Working directly with European colleagues in the PISTACH initiative, we are evaluating improved methods of retrieving coastal alongtrack altimeter data off Oregon, including improved editing and correction terms (for wet troposphere, etc.).
  • The improved alongtrack altimeter data in coastal regions are being assimilated into short-term (2-3 day) ocean forecasts, in which we are collaborating with NOAA funding off the U.S. West Coast.
  • Our analyses of previous missions in coastal regions will serve as metrics for Jason-3 data during its cal/val phase. If available, we will analyze overlapping data in our regions. If there is no overlap, the statistics of the coastal alongtrack data will still provide useful metrics.
  • In two of our present areas of interest (Oregon-Washington and the Patagonia Shelf) there are outfalls from large rivers, which will be examined in comparison to hydrologic data. These can be compared to the outfalls from India's large rivers.
  • Through collaborations with Indian colleagues and our Indian graduate student, we will include altimeter data from SARAL if possible.



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