Velocity Assimilation with Improved Synthetic Ocean Profiles (ISOP2): Validation Test Report
Abstract
Numerical ocean circulation forecasts diverge from reality due to non-deterministic processes or chaos. Through the process of data assimilation, the Navys operational ocean forecasting system routinely makes ocean forecast corrections utilizing temperature, salinity, and sea surface height anomaly observations. Velocity observations, however, are vector quantities that require different processing and are not presently used. To assimilate existing ocean velocity observations, which generally are depth limited in scope, vertical error covariances are needed to relate the velocity errors throughout the water column. In this report we show an approach that relies on an empirically derived vertical error covariance model to relate the errors between temperature and salinity. Geopotential height calculations transform temperature and salinity covariances of the Improved Synthetic Ocean Profile version 1 (ISOP1) system into corresponding geopotential covariances. Prior Navy vertical error covariances within the Navy Coupled Ocean Data Assimilation (NCODA) system provides information over only a short depth range. The new vertical error model allows for full depth error covariance required for assimilation of depth limited velocity observations, which are the bulk of available velocity data in the ocean. This report describes the methods and a prototype system for ocean velocity data assimilation incorporating the new geopotential covariances that upgrade the Improved Synthetic Ocean Profile system to version 2 (ISOP2). This new NOCDA/ISOP2 data assimilation methodology is employed in the Navys Couple Ocean Atmosphere Modeling Prediction System (COAMPS) providing greater forecasting capability because the prior system is unable to utilize in situ ocean velocity observations. Here we show velocity data assimilation validation experiments for Gulf of Mexico simulations during extensive drifter deployments in the summer of 2012 and again in 2020.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 04, 2022
- Accession Number
- AD1181822
Entities
People
- Brent P. Bartels
- Charlie N. Barron
- Chris J. Dehaan
- Clark D. Rowley
- Gregg A. Jacobs
- Hans E. Ngodock
- Ivo Pasmans
- Matt J. Carrier
- Max I. Yaremchuk
- Robert W. Helber
- Scott Smith
Organizations
- United States Naval Research Laboratory