Knorr
UHDAS and ADCP

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As of August 2005, the new suite of programs, UHDAS, is in use for ADCP data logging on the Knorr. This has been updated to run on Ubuntu 8.04 (Hardy Heron) in June, 2008. 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.

Data acquisition, automated processing, web serving and diskserving is done by the ADCP Linux pc, "currents". Currents belongs to the ship; Currents 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 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 opens a page that you might want to keep open as a UHDAS display, since we prefer that currents be kept in the Monitor tab during data acquisition. Various plots are generated on a regular basis for each instrument. A "profile plot" 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 "shallow" plot is an upper layer average vector plot shown over topography, color-coded with the temperature measured by the ADCP. The vector plot and three contour plots (as a function of time, longitude, and latitude) use the most recent 3 days of data. The data used are available through the NFS and Samba link.

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ADCP and UHDAS

The Knorr has two RDI Doppler sonars. The newest is a 75 kHz Ocean Surveyor ADCP (OS75) which can reach to 800 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 Julia 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. 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.

IMPORTANT ONLY the official ADCP Operator (SSSG Tech) 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 ADCP Operator and help us to maintain the integrity of the data.

IMPORTANT The figures should be updating regularly. If for some reason the figures quit updating, check the UHDAS logging panels on "currents" 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 processing interval, when a new data file is started.

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Acknowledgements

We are grateful to everyone who helps

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