DOI: 10.5061/dryad.g1jwstr3w
title: Near-inertial shear and kinetic energy in the North Atlantic experiment (NISKINe): Moored observations

description: An 18-month deployment of moored sensors in Iceland Basin allows
 characterization of near-inertial (frequencies near the Coriolis frequency
 f with periods of ~14 h) internal gravity wave generation and propagation
 in a region with an active mesoscale eddy field and strong seasonal wind
 and heat forcing. The seasonal cycle in surface forcing deepens the mixed
 layer in winter and controls excitation of near-inertial energy. The
 mesoscale eddy field modulates near-inertial wave temporal, horizontal,
 and vertical scales, as well as propagation out of the surface layer into
 the deep permanent pycnocline. Wind-forced near-inertial energy has the
 most active downward propagation within anticyclonic eddies. As oceanic
 surface and bottom boundaries act to naturally confine the propagation of
 internal waves, the vertical distribution of these waves can be decomposed
 into a set of “standing” vertical modes that each propagate horizontally
 at different speeds. The lowest modes, which propagate quickly away from
 their generation sites, are most enhanced when the mixed layer is deep and
 are generally directed southward.
description: These data were collected as part of the Near-Inertial Shear and
 Kinetic Energy experiment (NISKINe), which focused on the generation,
 propagation, and dissipation of near-inertial waves in the Iceland Basin.
 This specific dataset contains moored observations recorded in the center
 of Iceland Basin from May 2019 through October 2020. Data were collected
 on subsurface oceanographic moorings.
description: # Near-inertial shear and kinetic energy in the North Atlantic experiment
 (NISKINe): Moored observations
 [https://doi.org/10.5061/dryad.g1jwstr3w](https://doi.org/10.5061/dryad.g1jwstr3w) Corresponding author: Gunnar Voet, [gvoet@ucsd.edu](mailto:gvoet@ucsd.edu) ## Overview These data were collected as part of the Near-Inertial Shear and Kinetic Energy experiment (NISKINe), which focused on the generation, propagation, and dissipation of near-inertial waves in the Iceland Basin. This specific dataset contains moored observations recorded in the center of Iceland Basin from May 2019 through October 2020.  Data collection was funded through ONR awards N00014-18-1-2423 and N00014-22-1-2182. Three close-to-full-depth subsurface moorings were deployed in the Iceland Basin. The moorings were deployed for 18 months, from May 5, 2019, until October 5, 2020, in a triangular array separated by 15 km and centered around 59°6'N, 21°12'W in approximately 2,800 meters of water depth. The primary mooring, M1, was equipped with acoustic Doppler current Profilers (ADCPs), Sea-Bird SBE 37 CTDs, SBE 56 and RBR Solo thermistors, and turbulence-measuring χ-pods. Two additional moorings (M2 and M3) were equipped only with ADCPs. ## Description of the data and file structure **Data files for individual instruments** Archives `M1.tar.gz`, `M2.tar.gz`, and `M3.tar.gz` contain compressed directory structures with raw and processed data from ADCPs, SBE37s, and SBE56s for each mooring. Additional RBR Solo temperature time series from mooring M1 are contained in separate archives (due to their large file sizes) in `M1_RBRSolo_raw.tar.gz` and `M1_RBRSolo_proc.tar.gz`. Raw data files are specific to instrument vendors. All processed data (except for chipod, see next paragraph) are stored in netCDF format. Variables in processed netCDF files are described below for different instrument types. Processed data from turbulence-measuring χ-pods are contained in `M1_Chipod.mat` in MATLAB format. #### ADCP ADCP data were processed using [https://github.com/modscripps/velosearaptor](https://github.com/modscripps/velosearaptor). Structure: ``` Dimensions: (z, time) Coordinates: * time (time) * z (z) float64 ... : depth [m] Data variables: (12/15) pg (z, time) int8 ... : percent good per ensemble mean u (z, time) float32 ... : ensemble-mean eastward velocity [m/s] v (z, time) float32 ... : ensemble-mean northward velocity [m/s] w (z, time) float32 ... : ensemble-mean vertical velocity [m/s] e (z, time) float32 ... : ensemble-mean error velocity [m/s] u_std (z, time) float32 ... : eastward velocity ensemble-mean standard deviation [m/s] v_std (z, time) float32 ... : northward velocity ensemble-mean standard deviation [m/s] w_std (z, time) float32 ... : vertical velocity ensemble-mean standard deviation [m/s] amp (z, time) float32 ... : ensemble-mean backscatter amplitude temperature (z, time) float32 ... : ensemble-mean temperature [°C] pressure (z, time) float32 ... : ensemble-mean pressure [dbar] pressure_max (z, time) float32 ... : maximum pressure per ensemble mean [dbar] npings (z, time) float32 ... : number of pings in ensemble mean ``` #### SBE37 Seabird SBE37 data were processed using [https://github.com/gunnarvoet/sbemoored](https://github.com/gunnarvoet/sbemoored). Structure: ``` Dimensions: (time) Coordinates: * time (time) Data variables: p (time) float64 ... : pressure [dbar] t (time) float64 ... : temperature [°C] c (time) float64 ... : conductivity [mS/cm] SP (time) float64 ... : practical salinity [psu] SA (time) float64 ... : absolute salinity [g/kg] CT (time) float64 ... : conservative temperature [°C] sg0 (time) float64 ... : potential density referenced to 0 dbar minus 1000 [kg/m^3] ``` #### SBE56 Seabird SBE56 data were processed using [https://github.com/gunnarvoet/sbemoored](https://github.com/gunnarvoet/sbemoored). Structure: ``` Dimensions: (time) Coordinates: * time (time) Data variables: t (time) float64 ... : temperature [°C] ``` #### RBR Solo RBR Solo data were processed using [https://github.com/gunnarvoet/rbrmoored](https://github.com/gunnarvoet/rbrmoored). Structure: ``` Dimensions: (time) Coordinates: * time (time) Data variables: t (time) float64 ... : temperature [°C] ``` #### Chipod If more than one sensor were available, variables were averaged. Structure: ``` cp: data from each chipod concatenated in one structure cpg: average of gridded chipod data (10 min, 10 m) mooring: temperature, temperature gradient, N2, and velocity sourced from mooring. ``` Time vector is identical for `cp`, `cpg`, and `mooring`. ##### `cp` variables Variables from all chipod units. If variables from both sensor 1 and 2 are available, they are averaged. Depth is sourced from mooring sensor depths combined with sensor separations along the mooring line. Cleaning flags applied to 30sec chi, eps: |dTdz|&lt;5e-4, N2&lt;8.5e-7 Cleaning to chi, eps, Kt, Jq applied at 10 min: |dTdz| &lt; 5e-4; N2 &lt; 8.5e-7; eps &gt; 1e-5; Data density per 10min bin &gt; 30%; ``` chi: temperature variance dissipation (degC^2/s) eps: TKE dissipation (m^2/s^3) T: potential temperature from cubic Akima interpolation S: salinity, set to 35 by default dTdz, N2: potential temperature gradient (sensor brackets) and buoyancy frequency from dTdz only spd: flow speed at sensors Kt, Jq: temperature diffusivity and turbulent heat flux. Nchi: number of 30sec point included in 10min averages u, v: u and v from adcp at the depth of chipods. units: chipod serial number ``` ##### `cpg` variables Same as cp but gridded at 10-min, 10-meter ##### `mooring` Temperature and velocity data from the mooring ``` u, v: ADCP u, v interpolated on a 10m, 10-min grid Tm: original mooring temperature interpolated on a 10m, 10-min grid\ T: potential temperature computed from mooring T interpolated with cubic akima scheme and S reconstructed from T-S relationship dTdz: potential temperature gradient (sensor brackets) N2: buoyancy frequency computed from dTdz alone\ SfromT: Salinity derived from T-S relationship, interpolated from mooring file M1 pT: potential temperature using reference level at 0m ``` ### Gridded products The archive `gridded.tar.gz` contains depth-gridded velocity and temperature fields combining data from several instruments on each mooring. Files marked as `may2019`containing data from instruments that failed after just about two weeks. Note that after instrument failure, only one working ADCP was left on mooring M3; there is no gridded velocity product for the full time series for this mooring. The file `ADCP/proc/SN15694/M3_15694.nc` in the archive `M3` contains the full depth-gridded velocity record for the full 18-month record of this mooring. #### Gridded temperature Structure: ``` Dimensions: (depth, time) Coordinates: * depth (depth) ... : depth [m] * time (time) Data variables: t (depth, time) float64 ... : temperature [°C] ``` #### Gridded velocity Structure: ``` Dimensions: (z, time, adcp) Coordinates: * time (time) * z (z) int64 ... : depth [m] * adcp (adcp) int64 ... : ADCP serial number Data variables: u (z, time) float64 ... : eastward velocity [m/s] v (z, time) float64 ... : northward velocity [m/s] xducer_depth (adcp, time) float64 ... : ADCP transducer depth [m] temperature (adcp, time) float64 ... : ADCP temperature [°C] ``` ### Auxiliary data The auxiliary.tar.gz contains mooring schematics, clock drift information, and processed multibeam data for the bathymetry in the vicinity of the mooring array. Directory structure: ``` aux ├── bathymetry │   └── merged_100_-28_-21_56_61.nc ├── clock_drift │   ├── ADCP_time_offsets.txt │   ├── ADCP_time_offsets2.txt │   ├── RBRSolo_time_offsets.txt │   ├── sbe37_time_offsets.txt │   └── SBE56_time_offsets.txt ├── magnetic_declination.txt └── mooring_layouts ├── NISKIN_M1_final.pdf ├── NISKIN_M1_final.svg ├── NISKIN_M2_final.pdf ├── NISKIN_M2_final.svg ├── NISKIN_M3_final.pdf ├── NISKIN_M3_final.svg ├── niskine_M1_sensor_config.csv └── niskine_M1_sensor_config.pdf ``` #### Bathymetry Gridded multibeam product with ocean depth in m. File: `aux/bathymetry/merged_100_-28_-21_56_61.nc` Structure: ``` Dimensions: (lat: 2916, lon: 4082) Coordinates: * lat (lat) float64 ... latitude * lon (lon) float64 ... longitude ``` #### Magnetic declination File: `aux/magnetic_declination.txt` The file contains the magnetic declination (difference to true north) at the location and time of the moorings. #### Mooring layouts The directory `aux/mooring_layouts/` contains mooring diagrams for each of the moorings in `.pdf` and `.svg` formats. Additional information on sensor placement on mooring M1 is listed in `aux/mooring_layouts/niskine_M1_sensor_config.csv`. The PDF version of this file is a simple printout of the table with some color highlighting, but it contains the same information as the `.csv` file. #### Clock drifts Text files in the `aux/clock_drift/` directory contains listings of sensor clock offsets after mooring recovery. These have been corrected for in the processed data. ### Mooring locations File: `niskine_mooring_locations.nc` Structure: ``` Dimensions: (mooring: 3) Coordinates: * mooring (mooring) int64 24B 1 2 3 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] ``` ## Code/Software Data processing code is at [https://github.com/gunnarvoet/niskine-proc](https://github.com/gunnarvoet/niskine-proc).