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                    R E A D M E 
                    doc: Tue May 15 18:10:40 2012
                    dlm: Sat Mar 16 13:27:24 2013
                    (c) 2012 A.M. Thurnherr
                    uE-Info: 18 14 NIL 0 0 72 3 2 8 NIL ofnI
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This directory contains a re-implementation of the shear method for
LADCP velocity processing, written and copyrighted by  A.M. Thurnherr;
the appropriate reference is Thurnherr [J. Tech., 2012, DOI:
10.1175/JTECH-D-11-00158.1].

Essentially, the software is a re-implementation of the shear method
for LADCP velocity processing. Data editing borrows heavily from Eric
Firing's c/Matlab/perl code that was used extensively during the later
stages of the WOCE. However, some of the algorithms were simplified.
In particular,

1) a much simpler gridding algorithm is used, and
2) there is no support for using GPS data for velocity referencing.

In regions of good scattering, the shear output from this software when
applied to data collected with current RDI instruments can be expected
to be very similar to the corresponding output from Eric's code with
PPI editing disabled, except that the high wavenumbers are considerably
less damped in this re-implementation (see Thurnherr [2012]). In
regions of bad scattering, this software simply leaves gaps in the
shear profiles whereas Eric's code uses a low-pass filtered version of
the shear to interpolate across gaps in the high-resolution profiles.

While this software can be used to integrate LADCP shear data
vertically to calculate velocity profiles, velocity referencing must be
done with a single partial-depth velocity profile (e.g. from BT or
SADCP data). While the resulting profiles of absolute ocean velocity
are useful and very easily obtainable "first guesses", much better
profiles can typically be obtained by applying multiple simultaneous
referencing constraints with the the Shear Inversion method [Thurnherr,
J. Tech., 2010; DOI: 10.1175/2010JTECHO708.1].

THIS SOFTWARE CAN BE FREELY USED AND COPIED FOR EDUCATIONAL OR OTHER
NOT-FOR-PROFIT PURPOSES.

Currently, limited documentation is provided in the following set of
README files:

[README]		This overview

[README.Install]	Installation instructions

[README.ProcessData]	A HowTo for obtaining shear, as well as relative
			and absolute velocity profiles from CTD/LADCP
			data

[README.TimeLagging]	The most common problem encountered during
			processing of CTD/LADCP data with this software
			is failure of the CTD/LADCP time-lagging
			routine. This Readme provides additional
			information and tips for how to solve
			time-lagging problems.

[README.Output]		A description of the various files produced by
			this software

[README.PostEdit]	A HowTo for post-editing shear with different
			statistics, e.g. to filter data collected with
			the ADCP very close to the surface, where the
			ship's magnetic field can degrade the compass
			data. Also describes how the shear data can be
			gridded with statistics other than simple
			arithmetic mean.

[README.YoYo]		Notes on how to process data from "non-standard"
			casts, such as yoyo's and tow-yo's. 

NOTE: Most of the source files use a hard tab of 4 spaces, i.e. they
can be viewed correctly, e.g. with "less -x4".