DOI: 10.25919/5e8590724bebc
title: CCS - Saildrone SD1007 2018 V1

description: Measurements are made with a Battelle Seaology pCO2 monitoring system (ASVCO2) is similar to the system described in Sutton et al. (2014). A Seabird Prawler CTD (for Seawater Temperature and Salinity) is mounted on the keel, where the Dissolved Oxygen is measured by an Aanderaa optode. The pH is measured using a custom design pH sensor (SCRIPPS) based on a DuraFET sensor using either the internal of external reference (pHin, pHext). The seawater sensor intakes for the ASVCO2 , the Prawler CTD, the Aanderaa optode and the pH sensor are located at about 1m water depth. The CO2 measurement uses a bubble equilibrator (Sutton et al., 2014), where the air from the equilibrator headspace is circulated through a LI-COR 820 non-dispersive infrared detector (NDIR) for measurement of CO2. The system carries out an automated measurement sequence typically every 1 hour. At the beginning of each measurement sequence, the NDIR undergoes a two point calibration with a zero CO2 gas and a high CO2 standard span gas (typically 450-550 micromol/mol), which bracket the range of CO2 mole fractions in seawater and air. The zero CO2 gas is generated by cycling air through a soda lime chamber and silica gel to remove CO2 and water vapour, respectively. The CO2 span gas is prepared by the NOAA Earth Systems Research Laboratory in the USA and calibrated on the WMO X2007 scale with a standard deviation of 0.06 micromol/mol (http://www.esrl.noaa.gov/gmd/ccl/airstandard.html). Each measurement cycle of zero and span gas, equilibrator headspace, and air takes 20 minutes with the equilibrator headspace measurement occurring at about 17 minutes followed by the air measurement. The pressure measurements are considered the same for the equilibrator headspace gas and air measurements due to the design of the ASVCO2 system (Sutton et al., 2014) as are the temperature and salinity of the surface seawater and the equilibrator measured by the Seabird Prawler. The data from the ASVCO2, the Prawler CTD, and the pH sensor are transmitted through iridium, typically every 4 hours, whereas the optode data is received via Saildrone as part of 6 hourly netcdf files. The data is part of the calculations for fCO2 and gets added into the processed netcdf files. A. J. Sutton, C. L. Sabine, S. Maenner-Jones, N. Lawrence-Slavas, C. Meinig, R. A. Feely, J. T. Mathis, S. Musielewicz, R. Bott, P. D. McLain, H. J. Fought, and A. Kozyr (2014) A high-frequency atmospheric and seawater pCO2 data set from 14 open-ocean sites using a moored autonomous system. Earth System Science Data, 6, 353-366. doi:10.5194/essd-6-353-2014. Relevant carbon component details: make, model, serial number, firmware version, settings: Sensor | Make | Model | Serial Number | Calibration fCO2 sensor | Battelle | ASVCO2 | 0009 | Pre and post deployment calibration; Continuous (see below). T and S sensor | Seabird | Prawler CTD | 0038 | Factory calibrated DO sensor | Aanderaa | optode | 700 | CSIRO calibration lab, pre deployment; burned into sensors. Auxiliary instruments (see for information in folder ‘Saildrone Auxiliary instruments’) Sensor | Make | Model | Serial Number | Calibration Anemometer | Gill Instruments | 1590-PK-120 | 173302 | Factory calibrated CTD | Teledyne | CTD-NH | 2523 | Factory calibrated Barometer | Vaisalo Oyi | PTB210A | M4030152 | Factory calibrated Fluorometer | Wetlab | ECO | 1120 | Factory calibrated Air temperature, Rel. Humidity | Heitronics | CT15.10 | 12258 | Factory calibrated