Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

This is a series of deep CTD casts in the Puerto Rico Trench. The data were collected with the Deep Autonomous Profiler (DAP). The DAP system and example profiles are described in Muir et al. (2021).

The Deep Autonomous Profiler (DAP) was tested in the Puerto Rico Trench for a total of nine dives during September 2018. The DAP was deployed from R/V Endeavor (cruise EN622). The tests verified the vehicle's operations, checked the sensor accuracy at depth, and demonstrated the utility of the adaptive water sampling method.

Figure 2 of Muir et al. (2021) depicts the operational steps of the DAP. In summary, using drop weights, the profiler descends at a nominal speed of 60 meters per minute through the water column, collecting CTD data. Upon reaching the bottom, a timer is activated and an onboard algorithm processes the descent profile to set the trigger depths for any sample bottles set with an adaptive criteria. Bottom water samples can also be collected according to any preset delays.

The bottom time can vary anywhere from 5 minutes to 18 hours, depending on the objective of each dive and the amount of time allocated to the ascent and descent. A burn wire is used to release the drop weights when the planned bottom time limit is reached. During the ascent, at a nominal speed of 60 meters per minute, the Niskin bottles are triggered at any preset depths specified in the mission file or at adaptively calculated depths based on downcast data. When the DAP surfaces, a radio beacon, Iridium beacon, strobe, radar reflector, and flag are used for recovery by the ship.

For comparison, the shipboard CTD data is available from Rolling Deck to Repository (R2R) as DOI: 10.7284/134455.

BCO-DMO Processing:
- concatenated downcasts, upcasts, and bottom data into one file for each type;
- in those concatenated files, converted date/time field to ISO 8601 format;
- bundled the other files into .zip folders by file type.

Data Organization and File Naming Conventions:
There are several files available here. As stated above, the following three files were generated by BCO-DMO by concatenating the original .csv files provided for each part of each cast:

dap_downcasts_en622.csv = all of the downcast data (profiler going to the bottom);
dap_bottom_casts_en622.csv = all of the data from the portion of the casts where the DAP was resting at the bottom;
dap_upcasts_en622.csv = all of the upcast data (profiler returning to the surface).

In these there concatenated files, the csv_file_name column indicates the original .csv file name. These names correspond to the date and time of the cast (e.g. "20180915_121737_DOWN" = 2018-09-15 12:17:37).

The Supplemental Files here include the following Sea-Bird Files. Note that these files have similar date file names as the .csv files, but the times are a little bit off from the .csv files. This is because of when the vehicle's logging and the CTD logging were started.

bmp_files.zip = images of plots made using Sea-Bird software. Plots include sound velocity vs depth; and oxygen and temperature vs depth for each DAP cast.

cnv_files.zip = the Sea-Bird SBE 9 .cnv files for each DAP cast. Each file starts with standard Sea-Bird headers.

hex_files.zip = the Sea-Bird .hex files for each DAP cast.

The original .csv files (one per cast) are provided in down_casts.zip, bottom_casts.zip, and up_casts.zip. The .csv files in these folders have headers starting with latitude and longitude on row 1 and the column names on row 2.

NSF Award Abstract:
This project will build an autonomous system that measures physical, chemical and biological properties and samples seawater throughout the full global range of ocean depths (0 to 11 km below sea level). Because this system will be deployable over this entire depth range, it will significantly advance understanding of deep-sea chemistry, watermass structure and planktonic ecosystems at all water depths. Because the system will profile and sample deep water autonomously, it will replace human-guided wire-based operations for oceanic profiling and water sampling at any depth. Consequently, it will significantly reduce the time and expense required for on-site operations by allowing shipboard science parties to undertake other deck operations simultaneously with water-column sampling and profiling. Most uniquely, the proposed system will make pervasive study of the very deep (6000-11000 mbsl) ocean feasible for the first time. At completion of this project, the system will be made available to the scientific community as a shared-use instrument.

This autonomous system will profile the physical and chemical properties of the entire water column during the trip from sea surface to seafloor and back again. During the return trip, it will take up to 24 water samples with modified Niskin bottles and pressure-retaining water samplers. Sampling strategies will be flexible and easily programmed to autonomously take samples at specific depth horizons (e.g., 10 depths spaced between 100 and 10000 meters) or adaptively based on transitions recorded and automatically identified in salinity, temperature, density or oxygen content. The system will be tested in the laboratory and at sea on two trial expeditions in the second project year. The trial expeditions for this system will provide field opportunities, samples and data for scientists and students to study deep-sea biological, chemical and physical processes in the western North Atlantic and a deep-sea trench (probably the Puerto Rico Trench). The expeditions will focus on creating opportunities for students from URI and minority-dominated institutions, especially in Puerto Rico, where the second expedition may begin and end. The project will introduce undergraduate and graduate students to design of oceanographic instruments and sea-going research through: (i) an Ocean Engineering design class based on the proposed instrument development, (ii) inclusion of undergraduate and graduate students on the expeditions, (iii) ship tours and presentations in the port region(s), (iv) study by other graduate students of samples and data from the expeditions. Finally, the project will provide a stipend and tuition for graduate student training in scientific instrument design and software development. These efforts will address NSF Broader Impact criteria in several ways, including participation of women, persons with disabilities, and underrepresented minorities in science, technology, engineering, and mathematics (STEM) and development of a diverse, globally competitive STEM workforce.