Dataset: DAP CTD Data from the Puerto Rico Trench
Deployment: EN622

DAP CTD Data from the Puerto Rico Trench

View Data: For data, See Dataset Metadata Page: https://www.bco-dmo.org/dataset/892686

Principal Investigator:

Christopher Neil Roman (University of Rhode Island, URI)

Co-Principal Investigator:

Steven L. D'Hondt (University of Rhode Island, URI)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

An Autonomous Ocean Profiling and Water Sampling System for 0 to 11 km of Water Depth (DAP Test PR Trench)

Version:

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Description

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).

Methods & Sampling

Dataset acquisition description

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.

Data Processing Description

Dataset Processing Description

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.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1635466	NSF Division of Ocean Sciences

Instruments

Deep Autonomous Profiler

Supplied Name: DAP

Supplied Description:

Instrument Type

Generic Name: Deep Autonomous Profiler

Acronym: DAP

Generic Description:

The Deep Autonomous Profiler (DAP) is described in detail in the following publication:
Muir, L., Roman, C., Casagrande, D., and D'Hondt, S. (2021) The Deep Autonomous Profiler (DAP), a Platform for Hadal Profiling and Water Sample Collection. Journal of Atmospheric and Oceanic Technology, vol. 38, no. 10, pp. 1833–1845, 2021. doi:10.1175/JTECH-D-20-0139.1. URL: https://journals.ametsoc.org/view/journals/atot/38/10/JTECH-D-20-0139.1.xml

To summarize:
DAP is a full-ocean-depth profiler rated to 11 kilometers. It was designed to expand the capabilities of a CTD system to the full ocean depth (11 km) by removing the constraints associated with wire-based operations. Removing the tether allows the vehicle to autonomously profile and sample seawater into the hadal region. Because it only requires the ship for deployment and retrieval, the ship can perform other tasks while the DAP is underway. The only source of communication to the DAP while deployed are the acoustic releases.

The DAP is built around a 24-bottle Sea-Bird SBE 32 rosette for 10- or 12-Liter Niskin bottles. The large aluminum bottle-support rings from the standard rosette were modified to reduce weight and are held by the vehicle's custom frame. Syntactic foam provides buoyancy and drop weights are used for descent.

The DAP stands 3.2 meters tall and has a mass of approximately 1400 kilograms (kg) in air empty and 1700 kg when full of water. The titanium electronics bottle, tested to 960 decibars (dBar) in a pressure facility, was designed to house the embedded Raspberry Pi computer and power circuitry. This computer logs data from the SBE 9plus CTD and SBE 43 oxygen sensor, sends commands to the SBE 32 sampler carousel to trigger the sample bottles, and controls the burnwire release. Power for a nominal 24-hour operating time is provided by a 24-volt, 40-amp-hour oil-filled DeepSea Power and Light SeaBattery.

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. 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.

The vehicle can currently hold up to 24 Niskin bottles, and up to four pressure-maintaining sample bottles provided by the Scripps Institution of Oceanography.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
csv_file_name	Name of csv file	unitless	file_name
latitude	Latitude of deployment (from first row of csv file)	decimal degrees North	lat
longitude	Longitude of deployment (from first row of csv file)	decimal degrees East	lon
time_julian_day	Time of deployment as julian day	days	julian_day
ISO_DateTime_UTC	Date and time (UTC) of deployment in ISO 8601 format	unitless	ISO_DateTime_UTC
abs_pressure	Absolute pressure	decibars (dbars)	press
depth	Depth	meters (m)	depth
temperature	Water temperature	degrees Celsius	temp
pot_temperature	Potential temperature	degrees Celsius	potemp
conductivity	Conductivity	Siemens per meter (S/m)	cond
salinity	Salinity	practical salinity units (psu)	sal
density	Density	kilograms per cubic meter (kg/m^3)	density
oxygen	Oxygen concentration	milligrams per liter (mg/L)	O2
sound_speed	Sound speed	meters per second (m/s)	sound_vel

Database

Contribute Data

Dataset: DAP CTD Data from the Puerto Rico Trench
Deployment: EN622

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: DAP CTD Data from the Puerto Rico TrenchDeployment: EN622

Dataset acquisition description

Dataset Processing Description

Dataset: DAP CTD Data from the Puerto Rico Trench
Deployment: EN622