AUV Observations of Langmuir Lurbulence in a Stratified Shelf Sea
Data files
Aug 27, 2024 version files 9.09 GB
Abstract
Measurements collected by a REMUS 600 AUV off the coast of southern California demonstrate large-scale coherent wave-driven vortices, consistent with Langmuir turbulence (LT), played a dominant role in structuring turbulent dissipation within the oceanic surface boundary layer. During a 10-hour period with sustained wind speeds of 10 m/s, Langmuir circulations were limited to the upper third of the surface mixed layer by persistent stratification within the water column. The ensemble-averaged circulation, calculated using conditional averaging of AD2CP velocity profiles using elevated backscattering intensity associated with subsurface bubble clouds, indicates that LT vortex pairs were characterized by an energetic downwelling zone flanked by broader, weaker upwelling regions with vertical velocity magnitudes similar to previous numerical studies of LT. Horizontally-distributed microstructure estimates of turbulent kinetic energy dissipation rates were lognormally-distributed near the surface in the wave mixing layer with the majority of values falling between wall layer scaling and wave transport layer scaling. Partitioning dissipation rates between downwelling centers and ambient conditions suggests that LT may play a dominant role in elevating dissipation rates in the OSBL by redistributing wave-breaking turbulence.
README: AUV observations of Langmuir turbulence in a stratified shelf sea
https://doi.org/10.25349/D9MW50
Description of the data and file structure
This archive contains data collected off the coast of Santa Barbara, CA in May 2022 as described in section 2 of Fisher, A. W., & Nidzieko, N. J. (2024). AUV Observations of Langmuir Turbulence in a Stratified Shelf Sea. Journal of Physical Oceanography. doi.org/10.1175/JPO-D-23-0136.1.
Data are provided as MATLAB .mat files and all timestamps are in UTC.
Files and variables
File: data_archive.zip
Folders & Description:
- \GB4A_Airmar\ surface meteorological conditions measured by an Airmar 200WX mounted on the GB4A transponder buoy
- \Nortek_Signature1000\ Acoustic current profiles, backscatter intensity, and inertial measurements used in the characterization of Langmuir cell structure and circulation. Raw measurements are provided as well as data which has been motion corrected and converted to a ENU reference frame as described in section 2a of the paper. Motion-corrected ENU data are contained within files with the suffix *_cor.mat. While INS data from the Kearfott T24 data is not included in these files, but was used in the coordinate transformation and motion correction, such data is available from the authors upon request.
\REMUS\
House instrumentation from the REMUS 600 vehicle, which includes the following subdirectories- \ADCP\ measured water velocities in vicinity of the vehicle from upward and downward looking 600kHz ADCPs
- \BATHY\ bottom-tracking from downward looking ADCP
- \CTD\ temperature, conductivity, pressure measurements
- \GPSDATA\ GPS fix data acquired during mission circuit
- \STATE\ house variables describing vehicle state and attitude
- \220511_adc_clean\ processed ADCP current profiles from upward and downward looking ADCPs.
\RSI_MicroRider1000\
Turbulent microstructure measurements from a Rockland Scientific Microrider-1000 equipped with shear probes, microconductivity sensor, and fast thermistor. Raw data in RSI .P files are provided in addition to .mat files that have been converted using Rockland ODAS version 4.5.1\Sofar-Spotter\
CSV files containing the raw wave measurements from SoFar Spotter exported using sd_file_parser v1.7.12.py provided by SoFar Ocean. See python code for description of output file structure.