Index of /ftp/oceans/VOS_Gould_Lines
Please cite this data set as:
Takahashi, T., C. Sweeney and S. C. Sutherland. 2011. Underway pCO2 Measurements
in Surface Waters and the Atmosphere During the R/V Laurence M. Gould Expeditions.
http://cdiac.ess-dive.lbl.gov/ftp/oceans/VOS_Gould_Lines/. Carbon Dioxide Information Analysis
Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, Tennessee.
NOTE: Original LDEO data files for all cruises were updated on 11/12/2015 as follows:
These files have been reprocessed during the spring of 2015 in order to account for the
time lag of water from the ship’s intake to the pCO2 system. The timing of the seawater
temperature data measured with ThermoSalinoGraph (TSG) unit was adjusted to match the
timing of input temperature (Teq) of the pCO2 equilibrator. The time lag of be 3 or 6
minutes was applied depending upon cruises. The corrections applied to corresponding pCO2
data points are up to about ±8 μatm for the Palmer and Gould data and ±16 μatm for the
Healy data, while the mean of the corrections for each cruise is less than ± 1 μatm.
When the TSG (Thermosalinograph) temperature was judged unreliable, equilbrator
temperature was used to estimate SST by applying a constant off-set estimated using the
data from other legs. Therefore, the time-lag correction is not necessary.
As to atmospheric CO2 measurements, with the surface pCO2 observations, we have chosen to
reject air observations from these ships. It is not possible to accurately determine
amount of CO2 contamination from local sources including the ships exhaust systems, even
with the benefit of wind data. Severe CO2 spikes were found during a nearly head-on
relative wind conditions, suggesting local source of contamination.
With the benefit of 10 plus years of observations, editing, and analysis of surface water
pCO2, we consider that the running mean is not a satisfactory criterion for rejecting
“outliers.” Often large and rapid changes occur naturally in open ocean systems due to
patchiness of biological activities as well as to hydrodynamic conditions including
eddies, meandering of currents, local weather: yet these observations are valid and should
not be deleted. We, therefore, hand edit the data taking the coherence of pCO2 values with
other measured variables into consideration.