READ ME % Jim  Thomson, jthomson@apl.washington.edu, 09 Aug 2021

This folder contains data collected by the R/V Sounder during the Inner Shelf DRI field experiment in Sept and Oct 2017.  There are subfolders for Acoustic Doppler Current Profiler (ADCP) data and Conductivity-Temperature-Depth (CTD) data, respectively.  The files in each are organized by day. 




--- Details about the ADCP files --- 
These daily matlab files contain Acoustic Doppler Current Profilers data collected by the R/V Sounder during the Inner Shelf DRI field experiment in Sept and Oct 2017.  

The daily files are named with the date as yyyy-mm-dd.  

The data were post-processed by Mike Kovatch (SIO) to convert relative velocities to absolute (earth-reference frame) velocities, with GPS data merged to provide positions. 

The data are stored in structures, with field names explained with this example:
 
>> load('Sounder-2017-09-08-ADCP.mat')
>> ADCP = 

  struct with fields:

    time_dnum: [170×1 double]  % UTC timestamp in matlab datenum
        depth: [170×1 double]  	  % local water depth at the vessel position (from bottom-tracking)
            z: [1×30 double]		  % depth (rel. to surface) of each cell in the profile
          lat: [170×1 double]		  % vessel position
          lon: [170×1 double]	  % vessel position
            x: [170×1 double]		  % vessel position in local coordinate system
            y: [170×1 double]	  	  % vessel position in local coordinate system
            u: [170×30 double]        % east-west velocity component (m/s)
            v: [170×30 double]	  % north-south velocity component (m/s)
            w: [170×30 double]        % up-down velocity component (m/s)

The first dimension is the time and the second dimension is the vertical profile.




--- Details about the CTD files --- 
Sounder-YYYY-MM-DD.rsk is the raw data directly from the Concerto.

Sounder-YYYY-MM-DD-CTD.mat is the raw data broken up into downcasts with minimal processing (subtract Patm, remove data above 1m). The data are defined such that each cast is straight downward from the start of the cast.

Sounder-YYYY-MM-DD-CTD-mapped.mat is the data objectively mapped onto a uniform vertical grid (mapping description follows).

Sounder CTD processing notes:

- Subtract Patm (Terril MET buoy)

- Link up CTD clock with chart plotter to define location

- Define downcast as where CTD started cast and assume vertically downward

- Linearly interpolate raw data onto 10cm vertical grid

- Calculate and remove mean Temp/Cond profiles using quadratic best fit

- Find mean de-correlation Temp/Cond length scales using Gaussian fit

- Objective map raw data using the calculated de-correlation length scales

- Signal-to-noise ratio calculate using 2*RBR sensor error (to add human error) and 4*std(data) to account for majority of signal size

- Data with RMS error > 5% is removed to eliminate bad casts