Turnipseed CO Data Instructions Investigator: Andrew Turnipseed, NCAR/ACD turnip@ucar.edu Date: 1/25/2012 Filename: Turnipseed_RombasCOData.csv (comma delimited) Data Interval: 10 min. averages Initial Start time of file: July 1, 2011, 0:00:00 (MST) All CO data were taken from an inlet height of 3.5 m Missing data = -9999 Columns: Start_sec: Beginning of 10 min. period (seconds since July 1, 2011, 0:00:00 MST) End_sec: End of 10 min. period (seconds since July 1, 2011, 0:00:00 MST) Mid_sec: Midpoint of 10 min. period (seconds since July 1, 2011, 0:00:00 MST) Date: MM/dd/YY, Time: hh:mm:ss, Beginning of 10 min. period (MST) Day of Year: decimal day, Beginning of 10 min. period (MST) CO: carbon monoxide mixing ratio, ppbv Instrumentation: ThermoEnvironmental Gas Filter Correlation CO analyzer, Model 48 equipped with a heated Pt catalytic converter. Sampling Notes: The sampling cycle for the CO instrument involves a continuous cycle of measuring the atmospheric signal for 5 min., followed by 5 min. of scrubbed air (zero) using a heated Pt-catalytic converter. Each 5 min. cycle is averaged - then, the CO reported is obtained from the average of the (Signal cycle - the preceding zero) and (Signal Cycle - following zero). The time tag was obtained from the center of the each Signal Cycle. As the valve controlling the sampling cycle was on its own timer - the differing clocks caused the samples to not always be exactly 10 min. in duration and a bit irregular with respect to the NIST time. Calibrations: Calibrations using a NIST-traceable CO/air standard were conducted at 3 different times: prior to ROMBAS, following ROMBAS, and during ROMBAS (8/11/11). All 3 calibrations agreed to within 8% - so a single average calibration was applied to all data.