Data Processing:
Data are averages of samples replicates, the number of which is indicated as a data column. Standard deviation of replicates is included as a data column as well. Data has been visually QA/QC. Suspended Particulate Matter (SPM) is calculated by subtracting the weight of the pre-weighed filter where the sample was collected on, to the average of the sample plus filter weights. Estimates of SPM are not corrected for salts retained in filter and retained material. Quality flags "quality", quality = 1, good; 2 = medium; 3 = poor. The latter are assigned based on the coefficient of variation (cv) of replicate samples:

quality(cv<0.1) = 1;  % good

quality(cv>0.1) = 2;  % medium
quality(cv>0.5) = 3;  % poor
 

BCO-DMO Processing Notes:
Edits made:
- Parameter header names were renamed to BCO-DMO convention
- Blank data fields and data reported as -999 were edited to 'nd'
- Edited time to remove colons and drop unused seconds
- Edited precision of lat/lon to four decimals.
- Edited precision of SPM and SPM_sd to two decimals.
- Removed the comment information from the file header. Where
    necessary the information was incorporated into BCO-DMO
    metadata fields and retained entirely in Dataset Description.

NOTE:  Correspondence with the PI (2013.01.12) regarding sample numbers indicates that samples with a GEOTRACES sample number also had pigment samples taken for the WHOI Thorium group.  Those samples with -999 did not have corresponding pigment samples taken.  Sample numbers of -999 were subsequently edited to 'nd' and the following comment was retained in the file header as per the PI:

#samples from station 1 were collected with WHOI's GEOTRACES pump
#sample numbers for stations > 1 were collected with NASA's
# surface peristaltic pump

Additional GEOTRACES Processing: After the data were submitted to the International Data Management Office, BODC, the office noticed that important identifying information was missing in many datasets. With the agreement of BODC and the US GEOTRACES lead PIs, BCO-DMO added standard US GEOTRACES information, such as the US GEOTRACES event number, to each submitted dataset lacking this information. To accomplish this, BCO-DMO compiled a 'master' dataset composed of the following parameters: station_GEOTRC, cast_GEOTRC (bottle and pump data only), event_GEOTRC, sample_GEOTRC, sample_bottle_GEOTRC (bottle data only), bottle_GEOTRC (bottle data only), depth_GEOTRC_CTD (bottle data only), depth_GEOTRC_CTD_rounded (bottle data only), BTL_ISO_DateTime_UTC (bottle data only), and GeoFish_id (GeoFish data only). This added information will facilitate subsequent analysis and inter comparison of the datasets.

Bottle parameters in the master file were taken from the GT-C_Bottle_GT10, GT-C_Bottle_GT11, ODF_Bottle_GT10, and ODF_Bottle_GT11 datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the Event_Log_GT10 and Event_Log_GT11 datasets. McLane pump cast numbers missing in event logs were taken from the Particulate Th-234 dataset submitted by Ken Buesseler.

A standardized BCO-DMO method (called “join”) was then used to merge the missing parameters to each US GEOTRACES dataset, most often by matching on sample_GEOTRC or on some unique combination of other parameters.

If the master parameters were included in the original data file and the values did not differ from the master file, the original data columns were retained and the name of the parameters were changed from the PI-submitted names to the standardized master names. If there were differences between the PI-supplied parameter values and those in the master file, both columns were retained. If the original data submission included all of the master parameters, no additional columns were added, but parameter names were modified to match the naming conventions of the master file.

See the dataset parameters documentation for a description of which parameters were supplied by the PI and which were added via the join method.