4DVar Tutorial Introduction

4-Dimensional Variational (4D-Var) Data Assimilation Tutorial

This page is under construction

Download the code

All of the additional scripts necessary to run the 4D-Var tests are available from the ROMS Subversion (SVN) repository. The 4D-Var test cases are for the California Current System, 1/3 degree resolution, (WC13).

> svn checkout --username joe_roms https://www.myroms.org/svn/src/test my_test

Download Lectures

Links to the upcoming 2010 ROMS 4D-Var workshop lectures are provided below. We are planning to record the audio for these lectures to combine with the slides for future reference. These lectures are meant to supplement this 4D-Var tutorial.

• Lecture 1:   PDF   Primal 4D-Var
• Lecture 2:   PDF   The Mechanics of 4D-Var
• Lecture 3:   PDF   Dual 4D-Var
• Lecture 4:   PDF   4D-Var Diagnostics
• Lecture 5:   PDF   Observation Impact and Observation Sensitivity

Directory Structure

When the checkout is complete, you will have the following directory structure under your my_test directory.

 /WC13                      Main California Current System 4D-Var applications
      /ARRAY_MODES          Stabilized representer matrix array modes and clipping
      /Data                 Input data directory
      /Functionals          Analytical expression header file
      /I4DVAR               Primal form of incremental, strong constraint 4D-Var, I4D-Var
      /I4DVAR_impact        I4D-Var observation impact
      /Normalization        4D-Var error covariance normalization coefficients
      /plotting             4D-Var plotting scripts (Matlab and ROMS plotting package)
      /PSAS                 Dual form of 4D-Var, Physical-space Statistical Analysis System, 4D-PSAS
      /PSAS_impact          4D-PSAS observation impact
      /PSAS_sensitivity     4D-PSAS observation sensitivity (adjoint of 4D-PSAS)
      /R4DVAR               Dual form of 4D-Var, indirect representer method, R4D-Var
      /R4DVAR_impact        R4D-Var observation impact
      /R4DVAR_sensitivity   R4D-Var observation sensitivity (adjoint of R4D-Var)