4DVAR Assimilation of simulated wide-swath altimeter data into a high resolution ocean model
Event: 2018 Ocean Surface Topography Science Team Meeting
Session: Application development for Operations
Presentation type: Type Poster
Contribution: not provided
Abstract: this study examines the contribution of high resolution altimeter SSH observations from SWOT to the accuracy of the analysis and forecasting of a high resolution ocean model. Current altimeter data sampling of the ocean sea surface height is significantly limited in spatial density. This gap is expected to be filled with the advent of the wide swath altimeter which will be launched in the near future. This paper investigates its potential contribution to lowering the analysis and forecast errors in a realistic data assimilative ocean model, through assimilation experiments involving individual and combined existing altimeters (e.g. Jason and Altika) and simulated wide swath altimeter, in addition to routine SST and T/S profiles. Direct assimilation of SSH observations using weak constraints 4dvar approach will be discussed (Ngodock et al 2016), as well as recent developments of a multiscale capability for the 4dvar system that allows for the proper assimilation of high-resolution observations in a two-stage analysis procedure. The first stage assimilates a super-observation data set that attempts to capture large-scale features. The analysis for this stage becomes the background state for the second stage where the full (non-averaged) data set is assimilated; this stage attempts to fit the analysis to the deviations from the super-obs values (a proxy for the small-scale errors).