The Fall Rate of the T-7 XBT

Abstract

A theoretical model of expendable bathythermograph (XBT) fall rate is reviewed, and a new form of fall-rate equation is proposed to include near-surface transient effects. Comparisons are made of T-7 XBT and CTD (conductivity, temperature, and depth) depths of thermohaline features off Barbados. Fall-rate equation coefficients are derived and compared with the manufacturer-supplied coefficients. As other investigators have found, the Sippican equation consistently underestimates probe depth by as much as 35 m at 760 m. Analysis yields a new equation, Z= 6.798t-0.002383t sq. - 4.01, for depths greater than about 10 m. Considerable probe-to-probe variability is noted and is found to be primarily the result of differences in the linear term or terminal velocity of the probes; variation in effective drag resulting from probe irregularities is the likely cause. Recommendations for additional work are made.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1992
Accession Number
ADA254401

Entities

People

  • William J. Teague
  • Zachariah R. Hallock

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Engineered Resilient Systems
  • Weapons Technologies

DTIC Thesaurus Topics

  • Accuracy
  • Acquisition
  • Algorithms
  • Barbados
  • Bathythermographs
  • Data Acquisition
  • Data Science
  • Information Science
  • Intervals
  • Isotherms
  • Malfunctions
  • Measurement
  • Observation
  • Regression Analysis
  • Statistics
  • Terminals
  • Test And Evaluation

Readers

  • Computational Modeling and Simulation
  • Oceanography.
  • Thermal Physics or Thermal Science.