Abstract:

At the mouth of Mobile Bay (Main pass), a CTD survey was conducted using a Seabird (SBE) SBE 19plus V2 SeaCAT Profiler CTD on 2016-04-06. It measured depth, conductivity, temperature, salinity, beam attenuation, and density.

Suggested Citation:

Brian Dzwonkowski, Grant Lockridge, and Steven Dykstra.. 2017. CTD data at Main Pass, Mobile Bay, April 2016. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7NZ862C

Purpose:

The objective of this ongoing research is to identify the influence of fluvial water and its suspended particulate matter on coastal regions including the ecosystem and its susceptibility to oil. This particular study aims to understand the nature of buoyant freshwater plumes in shallow micro-tidal environments. Hydrographic surveys were conducted with a CTD. Note the day was quite windy, so we had to anchor off at each station. Both a LISST and CTD cast were made at each station. Drifters were also released along the transect stations prior to the CTD/LISST cast. Data with the drifter release and LISST cast are associated with individual data submissions.

Data Parameters and Units:

FILENAME convention: Surveyname_ddMMMMMYYYY_CTDnamecastnumber_stationlocation e.g. DZ_06April2016_Mini000_cr Stations locations/Cast Time(CDT) in Main Pass, Mobile Bay. Each CTD cast file is organized as: Column 1 = Temperature [ITS-90, deg C] Column 2 = Conductivity [uS/cm] Column 3 = Pressure, Strain Gauge [db] Column 4 = Salinity, Practical [PSU] Column 5 = Sound Velocity [Chen-Millero, m/s] Column 6 = Density [sigma-t, Kg/m^3] Column 7 = Depth [salt water, m] Column 8= Specific Conductance [uS/cm] Column 9 = Beam Attenuation, Chelsea/Seatech [1/m]

Methods:

CTD was allowed to soak for approximately 1 minute at shallow depth than raised to the near-surface before beginning the descent to the bottom. Bottom was determined when casting line went slack, at which point the CTD was raised to the surface. Shoal west (sw): 30 14.6174 88 04.1607 Time: 12:30 CDT Shoal center (sc):30 14.3670 88 03.6461 Time: 12:21 CDT Shoal east (se):30 14.1383 88 03.1365 Time: 12:11 CDT Shoal shoal (ss): 30 13.8965 88 02.6461 Time: 11:59 CDT Channel west (cw) (30 13.7800 88 02.3971 Time: 11:49 CDT Channel center RED CAN (cr): 30 13.6678 88 02.1323 Time: 11:35 CDT (ESTIMATED) (Half down cast) Channel east (ce): 30 13.5469 88 01.8825 Time: ~11:18 CDT (NO DATA) Channel far (cf): 30 13.4824 88 01.7444 Time: ~11:27 CDT (NO DATA) NOTE 1: Channel East Station was done, then a front was observed and we decided to sample Channel Far Station due to a frontal feature separating the two sites. Unfortunately, the data cast did not collect data, however LISST data was collected. NOTE 2: Normally Channel Center station is done directly in the channel center, due to weather and boat traffic the station was take just inside the channel (west) of the Red nun marking the channel.

Instruments:

Seabird (SBE) SBE 19plus V2 SeaCAT Profiler CTD, Chelsea/Seatech transmissometer

Individual Files: