README: Boundary Layer Turbulence and Abyssal Recipes (BLT): Moored Observations

https://doi.org/10.5061/dryad.v15dv424f

Corresponding author:
Gunnar Voet, gvoet@ucsd.edu

Overview

These data were collected as part of the Boundary Layer Turbulence and Abyssal Recipes (BLT Recipes) Experiment which focused on near-bottom processes within a continental slope canyon on the eastern side of the Rockall Trough, off Ireland. This specific dataset contains moored observations from various sites within the canyon.
Data collection was funded through NSF award OCE-1756264.

Short-term mooring June/July 2021:

• MP1: A McLane Moored Profiler was deployed for one week in July 2021 and was outfitted with a Seabird SBE52 CTD, a Falmouth Scientific Inc. acoustic current meter, a Turner C-FLUOR fluorometer and two fast-sampling thermistor probes. The mooring had a downward-looking RDI Longranger 75 kHz Acoustic Doppler Current Profiler (ADCP) mounted in the top float.

Mooring July 2021 - August 2022:

• TCHAIN: A NIOZ thermistor chain with a downward-looking RDI Longranger 75 kHz ADCP mounted in the top float. Only ADCP data are archived here for this mooring, for thermistor data contact Hans van Haren at NIOZ.

Moorings July 2021 - October 2021:

• MP2: Profiling mooring MP1 was re-deployed, without the fluorometer and fast-sampling thermistor probes mounted on the McLane Moored Profiler, in July 2021. MP2 was recovered in October 2021.
• MAVS1 & MAVS2: Two moorings, which consisted of ~80 Seabird SBE56/RBR Solo thermistors, one to two SBE37 microcats, and 8 Modular Acoustic Velocimeters (MAVS), were deployed in July 2021. Both moorings also had one downward-looking RDI Longranger 75 kHz ADCP mounted in the top float. MAVS1 and MAVS2 were recovered in October 2021. Modular Acoustic Velocimeter data will be published elsewhere.

Moorings October 2021 - August 2022:

• MP3: Mooring MP2 was re-deployed without any technical changes as and redeployed in a cross-canyon configuration. During the third cruise in August 2022, another 6 microstructure stations were conducted with the epsi-fish profiler and all moorings were recovered. MP3 was recovered in August 2022.
• MAVS3 & MAVS4: Moorings MAVS1 and MAVS2 wered re-deployed with only minimal changes in October 2021 as MAVS3 and MAVS4. MAVS3 and MAVS4 were recovered in August 2022. Modular Acoustic Velocimeter data will be published elsewhere.

Short-term mooring August 2022:

• G1: An upward-looking RDI Longranger 75 kHz ADCP was deployed near the seafloor for about 5 days in August 2022.

Description of the data and file structure

The dataset contains data files derived from RDI Longranger 75 kHz ADCPs, Seabird SBE37 CTDs, McLane Moored Profilers, and thermistors (a mixture of RBR Solo and Seabird SBE56). A file with mooring locations and bottom depths (based on multibeam bathymetry) is provided in addition.

Mooring location

File: mooring_locations.nc

Structure:

Dimensions:        (mooring)
Coordinates:
  * mooring        (mooring) <U6 'MP1' 'MP2' 'MP3' ... : mooring ID
Data variables:
    lon_planned    (mooring) float64 ... : planned longitude
    lat_planned    (mooring) float64 ... : planned latitude
    lon_actual     (mooring) float64 ... : actual longitude from trilateration
    lat_actual     (mooring) float64 ... : actual latitude from trilateration
    offset         (mooring) float64 ... : offset from planned location [m]
    depth_planned  (mooring) int64 ... : depth at planned location [m]
    depth_actual   (mooring) int32 ... : depth at actual location [m]

ADCP

Files: <mooring_id>_adcp.nc

Structure:

Dimensions:       (depth, time)
Coordinates:
  * depth         (depth) float64 ... : depth [m]
  * time          (time) datetime64[ns] ... : time
Data variables:
    pg            (depth, time) float64 ... : percent good per average
    u             (depth, time) float32 ... : eastward velocity [m/s]
    v             (depth, time) float32 ... : northward velocity [m/s]
    w             (depth, time) float32 ... : vertical velocity [m/s]
    e             (depth, time) float32 ... : error velocity [m/s]
    u_std         (depth, time) float32 ... : u standard deviation per average [m/s]
    v_std         (depth, time) float32 ... : v standard deviation per average [m/s]
    w_std         (depth, time) float32 ... : w standard deviation per average [m/s]
    e_std         (depth, time) float32 ... : e standard deviation per average [m/s]
    amp           (depth, time) float32 ... : backscatter amplitude [db]
    temperature   (time) float32 ... : ADCP temperature [°C]
    pressure      (time) float32 ... : ADCP pressure [dbar]
    pressure_std  (time) float32 ... : ADCP pressure standard deviation per average [dbar]
    pressure_max  (time) float32 ... : ADCP pressure maximum per average [dbar]
    npings        (time) int16 ... : number of pings in average
    xducer_depth  (time) float64 ... : transducer depth from pressure [m]

SBE37

Files: <mooring_id>_sbe37_sn<serial_number>.nc

Structure:

Dimensions:  (time)
Coordinates:
  * time     (time) datetime64[ns] ... : time
Data variables:
    p        (time) float64 ... : pressure [dbar]
    t        (time) float64 ... : in-situ temperature [°C]
    c        (time) float64 ... : conductivity [ms/cm]
    SP       (time) float64 ... : practical salinity
    SA       (time) float64 ... : absolute salinity [kg/m^3]
    CT       (time) float64 ... : conservative temperature [°C]
    sg0      (time) float64 ... : potential density [kg/m^3]

MP

Files: <mooring_id>_mp.nc

Structure:

Dimensions:  (time, z)
Coordinates:
    p        (z) uint16 ... : pressure [dbar]
  * z        (z) float64 ... : depth [m]
  * time     (time) datetime64[ns]... : time
    profile  (time) float64 ... : profile number
    hab      (z) float64 ... : height above bottom [m]
    time2    (z, time) datetime64[ns] ... : 2D time
Data variables:
    datenum  (time) float64 ... : Matlab time
    yday     (time) float64 ... : year day
    year     (time) float64 ... : year
    t        (z, time) float64 ... : in-situ temperature [°C]
    th       (z, time) float64 ... : potential temperature [°C]
    c        (z, time) float64 ... : conductivity [mS/cm]
    sgth     (z, time) float64 ... : potential density [kg/m^3]
    s        (z, time) float64 ... : practical salinity
    u        (z, time) float64 ... : eastward velocity [m/s]
    v        (z, time) float64 ... : northward velocity [m/s]
    w        (z, time) float64 ... : vertical velocity [m/s]
    pitch    (z, time) float64 ... : pitch 
    roll     (z, time) float64 ... : roll
    dpdtave  (z, time) float64 ... : profiling speed
    eps      (z, time) float64 ... : dissipation of turbulent kinetic energy based on density inversions [W/kg]
    eps_t    (z, time) float64 ... : dissipation of turbulent kinetic energy based on temperature inversions [W/kg]
    SA       (z, time) float64 ... : absolute salinity [kg/m^3]
    CT       (z, time) float64 ... : conservative temperature [°C]
    P        (z, time) uint16 ... : 2D pressure
    N2       (z, time) float64 ... : buoyancy frequency [1/s]

Additionally, for MP1:
Files: mp1_chi.nc

Structure:

Dimensions:  (time, z)
Coordinates:
  * time     (time) datetime64[ns] ... : time
  * z        (z) float64 ... : depth [m]
    hab      (z) float64 ... : height above bottom [m]
Data variables:
    chi2     (z, time) float64 ... dissipation of thermal variance [K^2/s]

Gridded thermistor data

Files: <mooring_id>_gridded_temperature.ta.gz
The tar archives contain netcdf files with 2-day gridded temperature per file.

Structure:

Dimensions: (depth, time)
Coordinates:
  * depth        (depth) float64 ... : depth [m]
    sn           (depth) int64 ... : thermistor serial number
  * time         (time) datetime64[ns] ... : time
    sensor_type  (depth) <U9 ... : thermistor type (rbr/sbe)
Data:
    units:             °C
    long_name:         temperature

Raw data

Raw data are hosted on data servers at the Scripps Institution of Oceanography and available from the corresponding author per request.

Code/Software

Data processing code is at https://github.com/gunnarvoet/blt-proc.