Preparing Seabird CTD data for Ocean Data View (ODV)

In this post I will give a tutorial explaining the procedure I use to prepare sampled marine data (mostly SeaBird CTD data) to be plotted using the Ocean Data View (ODV) software.

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 some 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:

Exporting the data to text file. The .cnv files include header, metadata and only then the sampled values. To be separate the metadata from the data we export the data to text file using the Ascii Out option in SBEDataConversion.

Step five:

Data Validation. Many times some of the sensor reading is noisy or in someway inaccurate, before we go on with plotting the data we validate that all data are correct. This is conducted by plotting a scatter plot of the data using MS. Excel and visually observing the plots.

Step six:

Preparation of ODV compatible spreadsheet. ODV has very strict laws for importing spreadsheet data. To prepare the data in ODV format we use an MS. Excel template (you can grab it here) and save it as a delimeted text file.

Last step (seven):

Import the data to ODV and plot it.

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

ENJOY