Analyzing Temperature Data from XBT Grid Surveys.

• Main Author: Karweit,M
• Other Authors: NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY NSTL STATION MS
• Format: Text
• Language: English
• Published: 1984
• Subjects: Physical and Dynamic Oceanography; *Temperature; Norwegian Sea; Measurement; Bathythermograph data; Statistical analysis; Isotherms
• Online Access: http://www.dtic.mil/docs/citations/ADA140685; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA140685

This report considers a set of 78 XBT casts obtained by NAVOCEANO on the second leg of its cruise to the Norwegian Sea, Spring 1981. The data were taken in a grid pattern over a rectangular segment of ocean 66.95 -- 67.40 deg N latitude and -5.60 -- -4.35 deg W longitude, in a day and a half. The survey was to measure the spatial properties of the temperature field. This report analyzes the data with that perspective, and focuses on estimating isotherm surfaces as characterizations of the temperature field. The data from each cast are reduced to a set of depths at which the temperatures 0, 1, 2, and 3 dec C occurred. With these depths as data, two techniques are considered for estimating isotherm-depth maps: a two-dimensional Fourier series analysis, and an optimal objective analysis. Calculations of the spatial and temporal correlation of the data indicate that these analyses cannot be legitimately applied; and that a spatial characterization of this area is not possible with this data set. Mean depth and slope statistics for the isotherm depths are given. To complete the work, a discourse on measurement error with XBTs is presented, especially as it relates to the estimation of isotherm depths.