An Operational Global-Scale Ocean Thermal Analysis System
Abstract
OTIS is an ocean thermal analysis product developed for real-time operational use at the FNOC. It functions in an analysis prediction-analysis data assimilation cycle with an ocean mixed-layer model using the optimum interpolation formulation of Alaska and Elvander. Thus, climatology serves as the first-guess field for analysis of synoptic ship, bathythermograph, buoy, and satellite data, with the prediction from the mixed-layer model treated as a special class of data. An operational test, involving comparisons of OTIS against an existing operational ocean thermal structure model, was conducted during February, March, and April 1988. Qualitative comparison of the two products suggests that OTIS gives a more realistic representation of subsurface anomalies and horizontal gradients. Quantitative comparison of the two products with over 9900 independent (i.e., unassimilated) bathythermograph observations to calculate apparent root-mean-square (rms) errors indicate that OTIS gives a more accurate analysis of the thermal structure, with improvements largest below the base of the mixed layer. Regional differences in the relative performance of the models, which are probably related to the validity of the prescribed statistical parameters required by OTIS, are also noted from verification against the bathythermograph data. OTIS performs best relative to the existing model in the Indian Ocean, and poorest relative to this model in the eastern midlatitude Pacific. Subgrid-scale noise contaminates the apparent rms error statistics and obscures the relative grid-scale accuracy of the models. A general technique is presented to estimate grid-scale rms errors which are uncontaminated by subgrid-scale and instrumental noise in the observations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1990
- Accession Number
- ADA230007
Entities
People
- Kenneth D. Pollak
- Patricia A. Phoebus
- R. M. Clancy
Organizations
- United States Naval Research Laboratory