CTD Cast Files
Zipped folders of CTD data by cruise (1990 - present)
In addition to CalCOFI’s Bottle Database, which contains measurements derived from collected seawater samples, CalCOFI offers CTD sensor data, available by cruise. These data present water column profiles in higher resolution (1 meter instead of ~10 to 100-meter resolution).
These oceanographic data are collected using a CTD-Rosette. In the center of the ‘rosette’ of Niskin bottles, there is an instrument called a CTD (“Conductivity-Temperature-Depth”) that is equipped with sensors to measure various parameters. Available parameters include temperature, conductivity/salinity, dissolved oxygen, fluorescence/chlorophyll-a, nitrate, and many more.
CTD data are available from 1990, when CalCOFI began using a CTD-Rosette, to the present. CalCOFI uses an SBE 911plus CTD surrounded by a rosette of 24 10-liter Niskin bottles. See CTD / Bottle Sampling for more details.
The CTD Cast Files table (below) provides raw and processed & corrected CTD sensor data available for download
CTD Data Descriptions
- Raw CTD Data: Data files (.xmlcon, .hex, .bl, .nav, .prn, .mrk, .hdr) directly from SBE Software (Sea-Bird Scientific) with no processing or corrections applied.
- Final 1m-Binned: CTD data that have passed through the CalCOFI quality control process. After standard Seasoft-processing (Sea-Bird Scientific's data-processing suite) tuned for our SBE 911plus CTD, the .asc files are processed by SIO-CalCOFI in-house software (BtlVsCTD). Averaged (4-sec or 1 meter bin-averaged) CTD sensor data are matched with corresponding bottle data, then cruise-corrected and station-corrected. Zipped file includes: metadata and .asc, .hdr, .btl, and upcast & downcast .csvs ("u" and "d"; by station and concatenated).
- Cruise-corrected CTD data: CTD sensor data that are corrected using regression coefficients derived from 4-sec average sensor data vs bottle data comparisons for the entire cruise, meaning all casts with bottle samples (n=~1400; fliers omitted; column labels '_CruiseCorr').
- Station-corrected CTD data: CTD sensor data that are corrected using regression coefficients generated dynamically for each cast, 1m bin-averaged sensor data vs bottle data (n=~20; fliers omitted; column labels '_StaCorr').
- Since sensor behavior may vary from station to station, station-corrected CTD sensor data for salinity, oxygen, estimated nitrate, and estimated chlorophyll-a are considered the best, particularly for estimated nitrate.
- Preliminary 1m-Binned: CTD sensor data that have gone through SBE Data Processing and BtlVsCTD corrections applied, but using preliminary bottle data. After bottle data have been QAQC'ed, CTD sensor data are reprocessed to produce the Final 1m-Binned data.
- Test Cast/Prodo Cast: The Seabird 911plus CTD was first tested in Mar 1990 (9003JD) but still under development. CTD data from Mar 1990 - 1991 were occasional system & feasibility tests ("test casts"). As confidence in data quality improved, the CTD-Rosette began being used for daily primary productivity sample collection casts ("prodo casts") in 1992 (6 depths from one station per day).
- The first complete CalCOFI cruise using a CTD-Rosette on all stations was in Aug 1993 (9308NH).
- "FinalQC" files include additional quality-control code columns - latest format is 82-columns. These additional columns were added Nov 2015 but older cruises are being reprocessed so look for "finalQC" for the 82-column updated files. Final CTD data values should not change during the conversion from 65 to 82 columns. But data codes may be added to bad or missing sensor data (data code '9') and questionable sensor data (data code '8') in the corresponding "Q" column.
- The Windows-version of Sea-bird's SBE Data Processing Suite will not work on CTD data collected from 1990 to mid-1998. Those data must be processed by the DOS version of Seasoft, which can be successfully run in DOSBox on Windows 7 & 10.
- Some older cruises may not have final data available since they are being reprocessed using the current data-processing methodology for data-format continuity. All Raw CTD Data data files are available, however, processed data (preliminary or final bottle-corrected) will be posted when they are completed.
Concatenated downcast .csv (filename: 20-1902RL_CTDBTL_001-029D.csv)
CTD Cast Files