Data Assimilation Meetings at Reading

Date Meeting type Speakers
7 November 2012 DARC seminar Polly Smith (UoR)
Exploring dual formulation weak constraint 4D-Var data assimilation for the California Current System
In this talk I will present work investigating weak constraint ocean data assimilation methods using the dual formulation 4-dimensional variational (4D-Var) systems of the Regional Ocean Modelling System (ROMS) applied to the California Current System (CCS).
Model errors are a significant source of uncertainty in ocean forecasting. Weak constraint data assimilation offers a means for accounting for model errors by relaxing the commonly made assumption that the numerical forecast model is perfect and explicitly accounting for model errors in the assimilation. Since, in general, very little is known about the amplitude and structure of the model errors, practical implementation of the weak constraint approach offers a considerable challenge. A key difficulty is specification of the a priori model error covariances.
Here, I will describe issues related to application of the ROMS weak constraint dual form 4D-Var system to the CCS and present some results from experiments to identify and characterise the nature of the CCS model errors and thus inform the design of suitable prior model error covariance structures.

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