RB-05-06 TAO Cruise Readme File Ship: NOAA research vessel Ronald H. Brown Cruise Start: Charleston, SC, October 27, 2005 Cruise End: Miami, FL, November 25, 2005 Chief Scientist: Andy Shepherd System Operator: Jonathan Shannahoff Expocode: 33RO20051026 Method: Infrared absorption of dried gas. For details of the system see: Measurement of fugacity of Carbon Dioxide in surface water and air using continuous sampling methods. Wanninkhof and Thoning, 1993 in Marine Chemistry 44, 189-205, And: Feely, R.A., R. Wanninkhof, H.B. Milburn, C.E. Cosca, M. Stapp, and P.P. Murphy, A new automated underway system for making high precision pCO2 measurements onboard research ships, Analytica Chim. Acta, 377, 185-191, 1998. The three standard gases come from CMDL in Boulder and are directly traceable to the WMO scale. Sampling Cycle: The system runs on an hourly cycle during which 3 standard gases, 3 air samples from the bow tower and 8 surface water samples (from the equilibrator head space) are analyzed on the following schedule: Mins. after hour Sample 4 Low Standard 8 Mid Standard 12 High Standard 16.5 Water 21 Water 25.5 Water 30 Water 34 Air 38 Air 42 Air 46.5 Water 51 Water 55.5 Water 60 Water Units: All xCO2 values are reported in parts per million (ppm) and fCO2 values are reported in microatmospheres (uatm) assuming 100 % humidity at the equilibrator temperature. Notes: 1. Any values outside the range of the standards (303.23, 370.90, & 514.29 ppm) should be considered approximate (within 5 ppm). While individual data points above 514 or below 303 may not be accurate, the general trends should be indicative of the seawater chemistry. 2. There was a problem with the ship's salinity sensor and all values before October 28 at 1645 and after November 21 at 1530 were replaced. The new values were equal to the salinity from the Seabird Micro TSG - 0.077 where 0.077 was the average difference between the ship's TSG and the Seabird Micro TSG when the ship's TSG was giving good values. 3. The gas flow in the water phase dropped to near zero on November 10 from 0420 to 1304 and from November 22 at 0501 to November 23 at 1327. Almost all water values during these time periods have been removed. For questions or comments contact: Bob Castle 4301 Rickenbacker Causeway Miami, FL 33149 305-361-4418 robert.castle@noaa.gov