This website documents our USAP project of Southern Ocean current
observations on the RVIB Nathaniel B. Palmer and ARSV Laurence M. Gould
(PIs Teresa Chereskin, SIO and Eric Firing, UH). The program began in 1999
with the following goals:
to establish a program of
routine shipboard acoustic Doppler current profiler (ADCP) data
collection, processing, and dissemination on the Antarctic research
to provide improved monitoring of, and access to, the ADCP
data for individual science missions;
to improve public access to the data via the National
Oceanographic Data Center (NODC), Joint Archive for Shipboard ADCP Data
(JASADCP) at the University of Hawaii, and through our websites;
to use the data to examine the structure and
statistics of upper ocean currents in the Southern Ocean;
to augment the ongoing high resolution XBT time series in
Drake Passage with a time series of direct velocity observations.
Additional goals under our renewal project (2004) are
to add new velocity profiling capability through the addition of an
Ocean Surveyor 38 kHz phased array Doppler sonar (to improve range)
while maintaining the old RDI narrowband 150 kHz ADCP (for resolution);
to develop and implement a new Unix-based data acquisition program that
can handle multiple sonars and single
ping data acquisition (to improve the data recovery under sub-optimal
conditions such as heavy seas and ice).
As of November 2004, the new suite of programs, UHDAS, is in use for
ADCP data logging. New algorithms for automated processing and
plotting have also been implemented.
Although a final processing of the ADCP data set will be needed after
the cruise, we hope that the differences between the final version and
the automated processed version will be small. The biggest differences
will likely be found under adverse conditions: shallow water, heavy
seas, lack of scatterers, and bad weather.
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L. M. Gould ADCPs and Gentoo
The L. M. Gould has two RDI Doppler sonars. The newest is a 38 kHz
Ocean Surveyor ADCP (OS38) which can reach to 1200 m in good weather in
its deep-profiling mode. In bad weather, low scattering conditions, or
some speed/heading/sea state conditions that entrain
bubbles under the transducer, the range is less. There is also an RDI
150 kHz narrowband instrument (NB150) that profiles at higher
resolution to as deep as 300 m. Data acquisition for both sonars and
the requisite ancillary navigation streams occurs via the UHDAS
software, written by Eric Firing and Jules Hummon, University of
Hawaii. Ocean Surveyors are capable of running in either broadband
mode (higher resolution at the expense of penetration) or narrowband
mode (slightly deeper profiling but lower resolution). It is also
capable of interleaving these pings, which is what we prefer. We have
defaults set up for bottom track ON, 12 m bins in OS broadband mode (os38bb),
and 24 m bins in OS narrowband mode (os38nb). Our processing treats these
data streams as if they came from separate instruments, though work is
underway to combine them into a single high-resolution, deep-profiling product.
The NB 150 default setup is bottom track ON and 8 m bins.
**IMPORTANT** ONLY the ET should make changes to the UHDAS
configuration. There are only a few configurable parameters. Should you
want to make changes, please make the request to the ET and help us to
maintain the integrity of our program.
Data acquisition for both sonars, automated processing, web serving and
diskserving is done by our ADCP Linux pc, Gentoo. Gentoo belongs to the
ship; Gentoo is NOT available for general use. Please respect this
restriction and help us to maintain the integrity of this computer for
acquisition and processing. Access to raw data, preliminary processed
data, and plots is through NFS mount, SAMBA share, and this website.
This website provides access to preliminary processed matlab data files
and data plots. You can look at the plots and download both plots and
data using any browser and the links on the sidebar. Quick
Links are plots that you might want to keep open as a UHDAS
display, since we prefer that Gentoo be kept in the Monitor tab during
data acquisition. (They are the same plots that can be viewed using
the PLOT tab of UHDAS on Gentoo). The profile plots show the most
recent 5 min of data,
with profiles of averaged currents, percent good, and a color contour
of the amplitude for each sonar data type. The vector and contour links
point to plots that give an overview, with vector showing the currents
from a single depth layer
on a map with topography and contour showing the time evolution.
In addition, there is a suite of standard plots produced for each sonar
data type, and to examine these, follow the sidebar link under web access
and choose the sonar and plot or data type. The data available through the
website are averaged data in Matlab files. Raw data are available
via NFS (Unix) and Samba (Windows) as
described in the NFS and Samba link.
**IMPORTANT** The figures should be updating regularly. If for some reason
the figures quit updating (either OS38 or NB150), check the UHDAS logging panels on Gentoo
under the Monitor tab and make sure everything is green. If they are,
DON'T ADJUST ANYTHING: the raw data are good, but the processing
software hit a glitch for some reason. There's not much anyone on the
ship can do about it but wait, and hope it recovers. There is a good
chance plotting will recover at the next even 2-hour interval, when a new
data file is started.
OS38 Photos links to a web page of photos (courtesy of
RPSC) that document the OS38 installation on the LMG during the August 2004
shipyard period in Fourchon, LA.
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We depend on the hard work and high competence of the Raytheon
personnel on the Palmer and the Gould; we are grateful for their
assistance, without which this project would be impossible. This
program is funded by the National Science Foundation Office of Polar
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