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OAS accession Detail for 0100287
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Title: Physical and chemical profile data collected from CTD in the R/V Knorr cruise KN200-2 during March 2011 in the North Atlantic Ocean (NCEI Accession 0100287)
Abstract: The dataset consists of 100 CTD casts in the region north of Flemish Cap. Some casts cover the full water column, while others only cover the upper 1000 db. The CTD casts were obtained with a SeaBird SBE911+ system, measuring temperature (2 sensors), conductivity (2 sensors), pressure, beam transmission, oxygen (plumbed in series with the primary T/C sensor pair), chlorophyll fluorescence, and turbidity. All sensors were sampled at 24 Hz.

The data were processed using the SeaBird data processing software suite, SBEDataProcessing-Win32. A low pass filter, with time constant of 0.15 s, was applied to the pressure record. To account for the transit time between the temperature and conductivity sensors, the conductivity measurements were aligned with the temperature measurements using empirically determined time delays. The primary conductivity was delayed by 0.011 s relative to pressure (this is in addition to the advance of 0.073 s which is performed by the SeaBird deckbox during data acquisition, thus resulting in a net advance of 0.062 s). The secondary conductivity was advanced by 0.050 s.

The oxygen voltage was advanced by 4 s relative to pressure. A correction for conductivity cell thermal mass effects was applied to both conductivity channels using the parameters recommended by SeaBird (alpha=0.03, 1/beta=7.0).
The temperatures, conductivities, and oxygen voltage were then median filtered using a 7-scan window. A loop edit step was then applied, whereby portions of the cast in which the pressure was not changing sufficiently fast (0.2 dbar/s) were removed. This was followed by computation of salinity, potential temperature, potential density, sound velocity, geopotential anomaly, and oxygen concentration. Finally, the data from the downcast were averaged into 1 dbar bins. Further details of the CTD data processing can be found in the header portion of the individual cast files.

The final data files contain raw sensor values (1 dbar bin averages) plus a number of derived variables (e.g., potential temperature, salinity, sigma-theta, oxygen). A full list of the output variables is contained in the header portion of the cast files. The casts were visually examined to determine the quality of the data from the 2 separate sensor suites (primary and secondary). A header line was placed in each file indicating the preferred sensor pair (PRIMARY or SECONDARY) if one was bad or whether both were of equal quality (BOTH GOOD).
Date received: 20121210
Start date: 20110303
End date: 20110328
Seanames: North Atlantic Ocean
West boundary: -46.01
East boundary: -39.999
North boundary: 53.003
South boundary: 46.999
Observation types: biological, chemical, physical, profile
Instrument types: CTD, fluorometer, radiometer, transmissometer
Datatypes: ALTIMETRY - SEA SURFACE HEIGHT, BEAM ATTENUATION COEFFICIENT, CONDUCTIVITY, DYNAMIC DEPTH ANOMALY, FLUORESCENCE, HYDROSTATIC PRESSURE, OXYGEN, Potential temperature (theta), SALINITY, SEA SURFACE TOPOGRAPHY, SIGMA-THETA, SOUND VELOCITY, surface irradiance, TRANSMISSIVITY, WATER TEMPERATURE
Submitter: Ullman, David
Submitting institution: University of Rhode Island; Graduate School of Oceanography
Collecting institutions: University of Rhode Island; Graduate School of Oceanography
Contributing projects:
Platforms: Knorr (316N)
Number of observations:
Supplementary information:
Availability date:
Metadata version: 7
Keydate: 2012-12-12 11:07:21+00
Editdate: 2022-03-29 13:34:06+00