DOI: 10.5061/dryad.cvdncjt7s
title: SWIFT data collected in the Southern California Bight by SWIFT drifters as part of the ONR Langmuir Circulation Departmental Research Initiative (LC-DRI)

description: This is the public archive for ADCP data collected with SWIFT drifters and
 Mixed-Layer Floats during the 'Langmuir Circulation' Office of
 Naval Research Departmental Research Initiative (LC-DRI) field experiment,
 conducted between March 19th and April 6th, 2017 in the Southern
 California Bight 40 km west of Catalina Island. The floats and drifters
 were deployed and recovered from the R/V R.G. Sproul during cruise SP1709
 (Cruise DOI: 10.7284/907464). SWIFTs were deployed during storms with wind
 speeds up to 20 m/s and sampled strong diurnal warm layers during weaker
 wind periods.
description: SWIFT drifters were deployed at the ocean surface and collected
 measurements of near-surface velocity in a surface following reference
 frame using high-resolution acoustic Doppler current profilers (ADCPs),
 Nortek Signature 1000s. Mixed-layer Floats control their bouyancy to
 profile vertically in the ocean, and measured conductivity, temperature
 and density measurements. Also contained in this file are raw ADCP data
 --  subject to minimal quality control onboard the SWIFTs, but are
 otherwise unprocessed other than conversion from binary. This
 'raw' data is available for turbulence estimates. The .zip file
 contains .mat files with data and a READ ME (.txt file) describing the
 data format. Processing codes for the SWIFT-mounted Signature 1000s can be
 found here:
 https://github.com/SASlabgroup/SWIFT-codes/tree/master/Signature.
description: Matlab is required to open the data files (.mat files) included
 in this archive.
description: # SWIFT Data collected in the Southern California Bight by SWIFT drifters
 as part of the ONR Langmuir Circulation Departmental Research Initiative
 (LC-DRI) The data contained in this archive are quality controlled SWIFT
 data and MLF data, as well as raw high-resolution velocity data collected
 with SWIFT drifters (Thomson et. al. 2012) in the Southern California
 Bight in March and April of 2017. ## Description of the processed SWIFT
 and MFL data and file structure Two structures, 'swift', and
 'mlf' are contained in LCDRI_dryad.mat. These data structures
 contain substructures (fields) with the processed data collected by
 individual instruments. Substructures are named by their serial number and
 the date the data collection began. For example,
 'swift.SN250404' contains data collected by SWIFT 25, beginning
 April 04. **SWIFT Structure Variables** time: time (matlab datetime) lon:
 longitude (degrees N) lat: latitude (degrees E) driftspd: drift speed
 (m/s) driftu: drift zonal velocity (m/s) driftv: drift meridional velocity
 (m/s) tair: 1 m air temperature (deg C) tsea: sea surface temperature (deg
 C) depth: depth of velocity bins (m) subu: zonal velocity (m/s) subv:
 meridional velocity (m/s) wavefreq: frequencies of wave power spectra (Hz)
 wavepower: wave energy per frequency (m^2/Hz) waveustokes: stokes drift
 from measured peak wave period and significant wave height (m/s) wavesigH:
 significant wave height (m) wavepeakT: energy weighted peak wave period
 (s) wavepeakdir: peak wave direction (deg from N) windu: 1 m wind speed
 (m/s) windfreq: frequencies of wind power spectra (Hz) windpower: wind
 energy per frequency (m^2/Hz) surfz: depth of dissipation bins (m)
 surftke: surface dissipation (m^2/s^3) **MLF Structure Variables** time:
 time (matlab datetime) depth: depth bins (m) lon: longitude (degrees N)
 lat: latitude (degrees E) temp: temperature (deg C) sig: density
 (kgm^(-3)) sal: salinity (psu) ## Description of the raw ADCP data and
 file structure Data files are named using the serial number of the SWIFT,
 followed by the time at the start of the ADCP burst. Each file contains
 data from a single 8-minute ADCP burst, contained in two Matlab
 structures: 'avg' and 'burst', which contain data from
 the four slanted broadband beams and the single high-resolution
 pulse-coherent central beam, respectively. Note: there is also an empty
 'echo' structure, which is filled only when the ADCP is
 operating in echo mode. The HR 'burst' data are of primary
 interest for turbulence calculation. The fieldnames within the burst
 structure are as follows: time: datetime stamp for each ADCP ping.
 Temperature: temperature measured by the CTD (deg C) Presssure: pressure
 at the ADCP (deg) Heading: heading of the ADCP (deg) Pitch: pitch of the
 ADCP (deg) Roll: roll of the ADCP (deg) CellSize: separation between
 vertical bins (m) Blanking: distance from transducer to first bin (m)
 VelocityData: along-beam velocity values for the four broadband beams
 (ms^{-1}) AmplitudeData: acoustic backscatter amplitude (counts)
 CorrelationData: pulse-pair correlation (%) Fieldnames in the
 'avg' structure are the same. ## Sharing/Access information N/A
 ## Code/Software SWIFT codes for processing SWIFT-mounted Signature 1000
 burst data can be found here:
 [https://github.com/SASlabgroup/SWIFT-codes/tree/master/Signature](https://github.com/SASlabgroup/SWIFT-codes/tree/master/Signature)