VERTIGO CTD-ODV Files Readme

 


 

 In order to summarize CTD and bottle-discreet data (nutrients, pigments) in Ocean Data View (ODV), some different hunks of info had to be brought together.  These include the physical information from the CTD casts, the Lat/Lon and Time/Date info of the Event Log and the results of nutrient analyses.  The CTD numbers used for this were obtained from the http site of Damien Kunz, an undergraduate working Dave Siegel.  You can access the original .cnv files from:

 

http://www.icess.ucsb.edu/~damk2000/

 

These files are preferred over the ones also accessible from the VERTIGO website, as they’ve tweaked things slightly.  Damien also binned the data by depth/pressure and generated files summarizing the physical parameters from bottle tripping logs using Sea-Bird utilities.  There’s a readme file at that location that describes well what he did for each of those files.

 

The excel files here include to worksheets that were used to generate comma-delimited .txt files that can be loaded into ODV.  The first sheet has numbers from Damien’s binned .cnv’s matched with Event Log information, used to generated the plots of Oxygen, Fluorescence, Transmission and Turbidity plotted on time vs. depth or density plots.  Note that the little thumbnail map of the station locations is supposed to be north of Hawaii, but for some reason ODV only has shorelines for the Big Island and not the rest of the islands.

The second sheet of the .xls contains the numbers for nutrients and other parameters needed to plot in ODV.  Pigments will be added to this in the future.

 

A little bit of QC was done of these files prior to plotting, which are included in the .xls and restated here.

 

QC Notes for CNVbin and BTL summary files

Many of the Transmissometer data (“Beam Attenuation, voltage 5”) during the early part of the cruise were not used due to electrical problems with sensor.  Essentially any value less than the typical low end value of 4.4V was suspected and all values below 4V were discarded.

 

CTD089bin.cnv contains a few lines of spurious data.  The results binned from depths 16 and 17 meters look good.

 

The summary files have dates and times which are GMT, unless otherwise noted.  N.B. that January 1=Julian Day 1.

 

In BTL file, turbidity values of “0.00” on cast 93 were assumed spurious…these were surface samples and not typically this low.  Deep water values in other BTL files equal to “0.00” were included.

 

Cast 69, bottle 2, has high ammonium and DIN, but low Nitrate+Nitrite values…only one of it’s kind in the dataset…all other instances of ammonium dominating DIN have it less than about 5 µM…assumed spurious and nutrient values discarded.

 

The ammonium data has a number of values higher than 0.5 µM…these weren’t thrown out, but are probably spurious.

 

There are roughly half a dozen instances where phosphate values are significantly different than Redfield compared to DIN…these all lie in very low DIN and fairly low phosphate ranges, so these values have been left in at the moment.

 

In the CNVbin file, all Turbidity data less than or equal to 0.000 was discarded.

 

ODV related files

We’ve included the finalized ODV files in a pdf for you viewing pleasure.  For those who might wish to do a little ODV-ing yourself, we’ve also included the .cfg files to help speed the process of plotting and the deployment graphic to place the CTD data in context of what was in the water and going on at the time.   The graphic includes gray bars which are intended to represent local night, approximately.

 

CHL, Dec. 14, 2004