Accession Number:

ADA179911

Title:

Deep-Ocean Bottom Pressure and Temperature Sensors Report: Methods and Data.

Descriptive Note:

Summary rept. Sep 83-May 85,

Corporate Author:

RHODE ISLAND UNIV NARRAGANSETT GRADUATE SCHOOL OF OCEANOGRAPHY

Personal Author(s):

Report Date:

1986-12-01

Pagination or Media Count:

119.0

Abstract:

This report documents ocean bottom pressure data collected in 11 deployments of pressure sensors under the Gulf stream northeast of Cape Hatteras in depths of 3300 to 3900 m. In past experiments pressure sensors suitable for ocean depths have typically exhibited systematic drifts in calibration that seriously contaminate any observed periodicities longer than a few days. We used Digiquartz sensors because they offered potentially much lower drift than other commericially available sensors. In these sensors, either a bellows or a Bourdon tube applies stress to an oscillating quartz-crystal beam, causing its oscillation frequency to vary. Several factors influence the amount of drifts bellow vs. Bourdon-tube construction applied pressure duration of deployment and, for some sensors, high-pressure preconditioning in the lab. For the sensors deployed in the Gulf Stream, the total drift during deployments lasting from 3 to 12 months ranged from undetectable 0.01 dbar to 0.20 to 0.50 dbar. About half of the total drift typically occurred within the first 6 days of deployment. We estimate the residual error in the final pressure records, after the dedrifting calculations, to be typically 0.02 dbar rms or 0.06 dbar rms if the first 6 days of the record are exxluded or included, respectively. This low drift error opens many possibilities for studies that require knowledge of the low-frequency dynamic pressure signal in the deep ocean.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Electrical and Electronic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE