Implementations of the Navy Coupled Ocean Data Assimilation system at the Naval Oceanographic Office

Abstract

The Naval Oceanographic Office uses the Navy Coupled Ocean Data Assimilation (NCODA) system to perform data assimilation for ocean modeling. Currently the system uses a 3D multivariate optimum interpolation (3D MVOI) algorithm to produce outputs of temperature, salinity, geopotential, and u/v velocity. NCODA is run in a standalone mode to support automated ocean data quality control (NCODA OcnQC) and to test software updates. NCODA is also coupled with the Regional/Global Navy Coastal Ocean Model (RNCOM/GNCOM). The RNCOM/NCODA system is being used as part of an Adaptive Sampling and Prediction (ASAP) pre-operational project, that makes use of the Ensemble Transform (ET) and Ensemble Transform Kalman Filter (ET KF) applied to ensemble runs of the RNCOM. The ET KF is used to predict the posterior error covariances resulting from possible profile measurements. These results aid in predicting the impact of ocean observations on the future analysis, and thus allow the direction of limited assets to areas that will have the maximum gain (for applications such as ocean acoustics). A review of these systems will be given as well as examples of the metrics used for the RNCOM/NCODA system, ensemble modeling, and ASAP.