Abstract:

This dataset contains CTD and ADCP measurements obtained in the Gulf of Mexico in the GC600 block near the Megaplume natural seep site from 2017-06-18 to 2018-02-02. Two moorings, one instrumented with five CTD instruments at ~4, 14.1, 24.3, 34.5, and 44.7 meters above the bottom, were deployed at 27.3695N, 90.5712W in about 1186 m water depth. Deployment was from the Oceaneering International, Inc. vessel Ocean Intervention II. Time series of pressure, temperature, and salinity were collected between 2017-09-02 and 2018-02-02. Two ADCPs were also deployed and instrumented with one microcat each. The 300kHz ADCP was deployed at 27.3711N, 90.5736W in 1174 m of water and the 600kHz at 27.3700N, 90.5717W in 1182 m of water. Data were collected between 2017-09-02 and 2017-11-20 (300kHz) or 2017-12-06 (600 kHz). Instrument recovery was undertaken by the vessel Connor Bordelon, contracted by Oceaneering International. An additional six CTD profiles were collected in the area: two on 2017-06-29, two on 2018-09-02, one on 2018-09-02, and one on 2018-02-02.

Suggested Citation:

Daniela Di Iorio, Andreas Thurnherr, Mahdi Razaz, James Kelly. 2019. Hydrographic and ADCP data obtained from Oceaneering vessel Ocean Intervention II in the Gulf of Mexico from 2017-06-18 to 2018-02-02. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-qyn1-sx24

Publications:

Razaz, M., Di Iorio, D., Wang, B., & MacDonald, I. (2020). Temporal Variations of a Natural Hydrocarbon Seep Using a Deep-Sea Camera System. Journal of Atmospheric and Oceanic Technology, 37(9), 1737–1751. doi:10.1175/jtech-d-19-0137.1

Razaz, M., Di Iorio, D., Wang, B., Daneshgar Asl, S., & Thurnherr, A. M. (2020). Variability of a natural hydrocarbon seep and its connection to the ocean surface. Scientific Reports, 10(1). doi:10.1038/s41598-020-68807-4

Purpose:

CTD and ADCP data were collected for the purpose of understanding physics near the bottom boundary, specifically (1) the dynamics and role of the vertical transport of methane and oil to the surface from a naturally occurring methane seep and (2) the turbulent bottom boundary layer dynamics that cause horizontal and vertical dispersal, including resuspension of hydrocarbon-containing deposits.

Data Parameters and Units:

Cruise cast files format: date[YYYYMMDD], time[HHMMSS.SS], sound velocity[m/s], conductivity[mS/m], depth[m], temperature[degC], battery[V], salinity[PSU], density[kg/m^3], calculated sound velocity[m/s]. CTD: Mooring_CTD: File names correspond to the instrument serial number. *.cnv files have the format temperature[deg C], conductivity[S/m], pressure[dbar], time[Julian day], and flag. There are also *derive.cnv files with the format temperature[deg C], conductivity[S/m], pressure[dbar], time[Julian day], depth[m], salinity[PSU], density[kg/m^3], potential temperature[degC], sigma-theta[kg/m^3], sound velocity[m/s], and flag. CTD: ADCP_CTD: time[seconds], depth[m], pressure[dBar], temperature[degC], conductivity[S/m], salinity[PSU], density[kg.m^3], potential temperature[degC], sigma t [kg/m^3], sound velocity[m/s], flag[0] ADCP: ensemble number, year[YY], month[MM], day[DD], hour[HH], minute[MM], second[SS], decimal second[SS], pitch[deg], roll[deg], heading[deg], temperature[degC], zonal velocity component u1 though zonal velocity component u8 [mm/s], meridional velocity component v1 through meridional velocity component v8[mm/s], percent good position1 1 through 8{%], percent good position 2 1 - through 8[%], percent good position 3 1 - through 8[%], percent good position 4 1 - through 8[%]. Note: For details please refer to the Readme file (DiIorio UGA GoMRI Bottom Boundary Study GOM 2017_2018_ReadMe.docx) included in the dataset. This dataset only includes hydrographic ADCP data, and other related datasets are available under GRIIDC Unique Dataset Identifiers (UDIs): R5.x270.000:0001, R5.x270.000:0002, and R5.x270.000:0003.

Instruments:

The mooring microcats (Seabird Microcat 37SM) were estimated to be separated by about 10.2m. The inner 3 instruments (nominal depths 1171.8, 1161.5, and 1151.3 m) did not have pressure sensors, and pressure records have been input as calculated with a 10.2m separation. More details are available in the ReadMe document in the General_Metadata directory. Measurements were collected at 90-second intervals. Two ADCP instruments were deployed, a Teledyne RDI Workhorse Sentinel operating at 300kHz and a Teledyne RDI Workhorse Monitor operating at 600kHz. Data were collected in beam coordinate mode at a rate of 1200 pings per hour. Bin sizes were 8 m for the 300 kHz instrument and 2m for the 600 kHz instrument. A Seabird Microcat 37SM microcat was mounted on each ADCP platform. The instrument on the 300 kHz ADCP was about 70 cm above the bottom (1173.8 m water depth), and the 600 kHz instrument was 5 cm above the bottom (1182.4 m water depth).

Individual Files: