Post processing CTD data using ODV

In this post I will give a tutorial explaining how to prepare SeaBird CTD data for analysis using ocean data view (ODV).

Both ODV and SeaBird CTD are near Oceanographic standard, but getting used to processing the CTD data for ODV takes some time. With the hope of saving you some of this time I detail the procedure we usually take at the Israeli School of Marine Sciences.

Step one: 

Convert the hex file downloaded frome the CTD or saved while sampling using SeaSave software to .cnv file. This step is conducted using the Data Conversion option in SeaBird data processing software (SBEDataProcessing).

Step two:
Align the CTD data. Since the CTD instrument is a combination of several sensors, each having a typical time lag the readings in one data scan does not really represent a single point in time for all water quantities. To compensate for this, CTD alignment is performed using the Align CTD option at the SBEDataProcessing.

Step three:

Average the CTD data by depth. Many times, having data values at fixed depth intervals (eg. 1m) is more convenient. To achieve that we use the Bin Average option in SBEDataProcessing.

Step four:

Import CNV files to ODV and validate the CTD measurements.

Step six:

Many times you sample discrete samples on the same xast you sampled using the CTD and you want to plot the data together. To do that you will have to:

1. Export the CTD data to spreadsheet
2. Open the spreadsheet externally (in excel or other spreadsheet software)
3. Add the discrete parameters and samples to the spreadsheet
4. open the spreadsheet in ODV. 

Last step (seven):

Import the data to ODV and plot it. This is beyond the scope of this series.

Thanks to my teacher Gitai Yahel who taught me this process.