• norsk
    • English
  • English 
    • norsk
    • English
  • Login
View Item 
  •   Home
  • Research centres and projects
  • Nansen Environmental and Remote Sensing Center (NERSC)
  • View Item
  •   Home
  • Research centres and projects
  • Nansen Environmental and Remote Sensing Center (NERSC)
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Open Boundary Conditions for the Extended Kalman Filter With a Quasi-Geostrophic Ocean Model

Evensen, Geir
Journal article
Thumbnail
View/Open
eve93.pdf (781.5Kb)
URI
https://hdl.handle.net/1956/3030
Date
1993-05-18
Metadata
Show full item record
Collections
  • Nansen Environmental and Remote Sensing Center (NERSC) [61]
Original version
Journal of Geophysical Research Oceans 1993;98(C9):16529-16546   https://doi.org/10.1029/93jc01365
Abstract
The formulation of consistent boundary conditions for the quasi-geostrophic (QG) model with an extended Kaiman filter in a data assimilation scheme is discussed. To form a well-posed boundary value problem for the QG model, the stream function must be specified at all boundaries and the vorticity must be specified at the inflow boundaries. The situation becomes significantly more complicated when proper boundary conditions are to be specified for the error covariance evolution equation. For closed or periodic boundaries no severe problems occur, but in general cases with open boundaries, only approximative methods can be used. Here a scheme is presented which allows for the stream function to be updated on the boundaries, e.g., from the use of measurements located close to the boundaries, or from meanders and eddies approaching the boundaries from the interior of the domain. Further, the boundary value problem for the error covariance evolution equation is treated extensively. It is demonstrated that numerical discretization of the error covariance evolution equation leads to severe numerical difficulties when open boundaries are used. An approximate numerical scheme that can be used to handle open boundaries with inflow and outflow is proposed, and examples are given to illustrate the method. Is is shown that the boundary scheme is consistent and can be used even with data located at inflow boundaries. However, the approximations used in the scheme may lead to loss of positive definiteness for the error covariance matrix and an algorithm must be used to ensure positive definiteness for long time integrations.
Publisher
American Geophysical Union

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit
 

 

Browse

ArchiveCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsDocument TypesJournalsThis CollectionBy Issue DateAuthorsTitlesSubjectsDocument TypesJournals

My Account

Login

Statistics

View Usage Statistics

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit