XCTD Test: Reliability and Accuracy Study (XTRAS)

Abstract

In May-June 1990 a test and evaluation of the newly developed XCTD (expendable conductivity, temperature, depth) probe was conducted in a region northeast of Barbados, where ideal conditions exist for such a test. Thirty-six XCTD probes were launched concurrently with nine CTD casts for intercomparison. The existing fall-rate equation (FRE) was found to be inadequate and new coefficients were computed by regression using the CTD data. After recalculating XCTD depths, simultaneous drops show significant probe-to-probe difference, indicating a nonsystematic difference in (primarily) the linear term in the FRE for each probe. Examination of temperature and conductivity shows a significant systematic offset of the XCTDs relative to the CTD, suggesting a calibration error. In addition, many of the probes exhibited huge, positive conductivity excursions indicative of conductivity cell malfunction. Sippican Ocean Systems has indicated that the cell malfunctions and the calibration problems are correctable, but it is not clear if there is a solution for the residual depth error. Keywords: Oceanographic equipment; Probes.

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 1990
Accession Number
ADA227527

Entities

People

  • William J. Teague
  • Z. R. Hallock

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Materials and Manufacturing Processes
  • Weapons Technologies

DTIC Thesaurus Topics

  • Accuracy
  • Acquisition
  • Calibration
  • Coefficients
  • Conductivity
  • Data Acquisition
  • Equations
  • Errors
  • Malfunctions
  • Measurement
  • Oceanographic Equipment
  • Oceanography
  • Oceans
  • Physical Properties
  • Reliability
  • Salinity
  • Test And Evaluation

Readers

  • Oceanography.
  • Thermal Physics or Thermal Science.