Abstract:

This dataset contains CTD data collected during the R/V Point Sur cruise PS18-06 in the northern Gulf of Mexico from 2017-08-17 to 2017-09-03. The experimental site is on the continental slope of the northern Gulf of Mexico, next to the Deepwater Horizon Spill site. During the cruise, 15 CTD stations were conducted. The CTD used was a SEA-BIRD 911plus/917plus double sensors. Data from the CTD were acquired at 24 Hz. A log detailing cruise events and the sensors used is also included. Both raw and derived CTD profiles are available in ASCII and Matlab format (derived) with no low pass filter applied to preserve the high-resolution signals. 1-m bin averaged files are available in Matlab format; in this case, the odd-number column contains the downcast and the even-numbered column the upcast.

Suggested Citation:

Kurt Polzin, Zhankun Wang, Steven F. DiMarco. 2019. Oceanographic profiles from CTD casts collected during the R/V Point Sur cruise PS18-06 in the northern Gulf of Mexico from 2017-08-17 to 2017-09-03. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-8n2d-by19

Purpose:

Data was collected in support of studies of GoMix project with the goal of understanding the mechanisms, spatial inhomogeneity and temporal intermittency of boundary mixing along the Northern Deepwater Gulf.

Data Parameters and Units:

Raw ctd files: Altimeter [m], Beam Attenuation, WET Labs C-Star [1/m], Beam Transmission, WET Labs C-Star [%], Conductivity [uS/cm], Conductivity, 2 [uS/cm], Fluorescence (WET Labs CDOM [mg/m^3]), Fluorescence (WET Labs ECO-AFL/FL [mg/m^3]), Latitude [deg], Longitude [deg], Nitrogen Saturation [ml/l], Oxygen, SBE 43 [umol/l], Pressure, Digiquartz [dbar], Temperature [ITS-90, deg C], Temperature, 2 [ITS-90, deg C], Elapsed [seconds], flag [0,1]. Derived ctd files: Altimeter [m], Beam Attenuation (WET Labs C-Star [1/m]), Beam Transmission (WET Labs C-Star [%]), Conductivity [uS/cm], Conductivity, 2 [uS/cm], Fluorescence (WET Labs CDOM [mg/m^3]), Fluorescence (WET Labs ECO-AFL/FL [mg/m^3]), Latitude [deg], Longitude [deg], Nitrogen Saturation [ml/l], Oxygen, SBE 43 [umol/l], Pressure, Digiquartz [db], Temperature [ITS-90, deg C], Temperature, 2 [ITS-90, deg C], Time, Elapsed [seconds], Salinity [PSU], Salinity, 2 [PSU], Density [sigma-t, kg/m^3 ], Density, 2 [sigma-t, kg/m^3 ], Depth (salt water, lat = 28.1502, [m]), Descent Rate (WS=2, [m/s]), Geopotential Anomaly [J/kg], Potential Temperature [ITS-90, deg C], Potential Temperature, 2 [ITS-90, deg C], Absolute Salinity [g/kg], Absolute Salinity, 2 [g/kg], density (TEOS-10, [kg/m^3]), density (TEOS-10, 2 [kg/m^3]), potential temperature [ITS-90, deg C], potential temperature, 2 [ITS-90, deg C], flag. Please note the dataset includes the cruise report and the data documentation for the R/V Point Sur cruise PS18-06 led by chief scientist Kurt Polzin.

Methods:

Data from the CTD were acquired at 24 Hz. The CTD data were acquired by an SBE Model 11 plus CTD Deck Unit providing demodulated data to a computer in the engineering room running SeaBird software. After the cruise, the raw CTD data were run through the SeaBird data conversion software (SeaBird, Version 7.25.0.151). Data Conversion performs the first step in data processing, converting the raw CTD and auxiliary sensor data (typically frequencies and voltages) to engineering units. Data Conversion uses the instrument configuration file, which defines sensors, sensor channels, and calibration coefficients, to convert raw data to engineering units. The conductivity was advanced approximately 0.073 seconds relative to pressure for CTD alignment. No low pass filter was applied to the data to reserve the high-resolution signals. The practical salinity was calculated using DERIVE sal.cfg and the absolute salinity, density and potential temperature were calculated using DERIVE EOS80. The high-resolution data are available both in ASCII format and Matlab format. 1-m bin averaged files are created separately to generate the bin-averaged profiles and saved as Matlab files.

Instruments:

SEA-BIRD 911plus/917plus double sensors CTD, WET Labs CDOM fluorometer, WET Labs ECO-AFL/FL chlorophyll fluorometer, WET Labs C-Star transmissometer

Individual Files: