Aurora Australis Southern Ocean oceanographic data, voyage 1, 2002-2003 - ADCP data

Brief description

Oceanographic measurements conducted on voyage 7 of the Aurora Australis of the 2002-2003 season. These data are ADCP (Acoustic Doppler Current Profiler) data.

These data were collected/collated by Mark Rosenberg.

Final ADCP data for voyage au0201 (SAZ mooring turnaround and
iceberg B9B experiment), Aurora Australis Voyage 1 2002/2003, 17th Oct 2002 to
18th Nov 2002.

* The complete ADCP data for cruise au0201 are in the file:
au020101.cny (ascii format)
a0201dop.mat (matlab format)

* The "on station" ADCP data (specifically, the data for
which the ship speed was less than or equal to 0.35 m/s)
are in the files:
au0201_slow35.cny (ascii format)
a0201dop_slow35.mat (matlab format)

* The file bindep.dat shows the water depths (in metres) that
correspond to the centre of each vertical bin.

* The data are 30 minute averages. Each 30 minute averageing
period starts from the time indicated.
(so, e.g., an ensemble with time 120000 is the average from
120000 to 123000).

* ADCP currents are absolute - i.e. ship's motion has
been subtracted out.

* Note that the top few bins can have bad data from water dragged
along by the ship.

* Beware of data when the ship is underway - it's often suspect.



MATLAB VECTORS AND MATRICES:
============================

header info
-----------
for header info: column number corresponds to 30 minute average number
botd = mean bottom depth (m) over the 30 minute period
cnav = GPS info: don't worry about it
cruise = cruise number
date = ddmmyy (UTC)
ibcover = a bottom track parameter: don't worry about it
icover = percentage of 30 minute averageing period covered
by acceptable 3 minute ensembles
lastgd = deepest accepted bin in this profile
lat = mean latitude over the 30 minute period (decimal degrees)
lon = mean longitude over the 30 minute period (decimal degrees)
nbins = no. of bins logged (=60)
shipspeed = scalar resultant of shipu and shipv
shipu = ship's E/W velocity over the ground over 30 minute period
(m/s, +ve east)
shipv = ship's N/S velocity over the ground over 30 minute period
(m/s, +ve north)
time = hhmmss, time (UTC) at start of 30 minute averageing period
dectime = time in decimal days from start of year 2002 (e.g. midday on
January 2nd = 1.5000)


adcp data
---------
for adcp data matrices: row number corresponds to bin number
column number corresponds to 30 min. average no.
bindep = depth (m) to centre of each bin in the profile (will be the
same for all profiles)
ipcok = percentage of the profile period for which there was
good data in this bin (N.B. data=NaN when ipcok=0)
qc = a quality control value for each bin - see below
speed = scalar resultant of u and v
u = east/west current (m/s, +ve east)
v = north/south current (m/s, +ve north)



ASCII FORMAT FILE:
==================

* The file starts with a 3 line header.

* Then comes each 30 min. ensemble, as follows:

First, a 1 line header, containing

date (UTC) (dd-mmm-yyyy)
time (UTC) (hh:mm:ss)
% of 30 min average covered by acceptable 3 min. ensembles
deepest accepted bin in the profile
ship's E/W velocity over the ground over the 30min (m/s)
ship's N/S velocity over the ground over the 30min (m/s)
P= GPS position-derived velocity (D=direct GPS vel.; B=bottom track vel.)
mean longitude over the 30 min.
mean latitude over the 30 min.
% of interfix period for which there was bottom depth information
mean bottom depth over the 30 min.
0
0

Next, the data, from the shallowest bin to the deepest bin:

for each bin, there's 4 parameters:

u = east/west current (m/s, +ve east)
v = north/south current (m/s, +ve north)
qc = quality control value - see below
ipcok = percentage of the profile period for which there was
good data in this bin

Note that the data are written left to right across each line, then
onto the next line, etc. (so 4 bins on a full line)


quality control value:
----------------------
qc = %good / (Verr+0.05)

where:
%good = percent good pings after logging system screening
Verr = RMS error velocity (m/s).

Possible range of qc is 0-20, with an expected range of 0-10;
values of 0-4 indicate very poor data; values above 8 indicate
very good data.

Lineage

Progress Code: completed

Statement: As this metadata record was completed by AADC almost twenty years after data collection, guarantees cannot be made as to the data quality.

See the readme files in the downloads for more information.