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T-REX Intercomparison Analysis:HIAPER GV & UKMO FAAM BAe146April 17, 2007Ilana Pollack, Teresa Campos, and Andrew WeinheimerNCAR/ACD – CARI (Community Airborne Research Instrumentation) GroupLaura Pan and Sue SchaufflerNCAR/ACD – UTLS GroupJorgen Jensen and Allen SchanotRAF/EOL – Chilled Mirror DataRuth Purvis and Jim McQuaid BAe146 – Trace Gas Data
Notes: • Intercomparison flight data: RF 20060406, between 20:45:00 and 22:18:00 UTC • Additional information about the GV instruments, remarks on individual measurements, and applied corrections/calibrations to the final QC’ed data: See data quality reports and readme files posted on the T-REX data website • BAe trace gas data taken from final submitted version (r14)
Selecting the Intercomparison Part of the Research Flight: Altitude • From Lat, Lon, and Alt data, the selected time series of interest for comparison is 8:45:00 pm to 10:18:00 pm UTC.
Selecting the Intercomparison Part of the Flight: LAT and LON Time of interest between 8:45:00 pm and 10:18:00 pm
Ozone Comparison GV: O3 Chemiluminescence instrument BAe146: TECO 49 UV photometric instrument
Timeseries of O3 data D < 2 ppb D < 5 ppb The BAe O3 data was arbitrarily shifted by a constant offset of -13 sec to match major features in the GV O3 data. The blue trace is GV O3 mixing ratio while the red represents its associated uncertainty of ± (3 ppbv + 3% of the instrument reading).
GV and BAe146 O3 Correlation Plot (Some discrepancies may arise from the estimated constant time shift arbitrarily applied to the BAe data) Slope of linear fit = 1.18 R2 = 0.9921
CO Comparison GV and BAe146 use same commercial instrument: AL5002 Fast Carbon Monoxide (CO) (With an integration time of 10s the detection limit is < 2.0 ppbV) (Nafion drier used upstream of instrument)
Timeseries of CO data D < 3 ppb D < 7 ppb The BAe_CO data was arbitrarily shifted by a constant offset of -13 sec to match features in the GV CO and O3 data sets.
GV and BAe146 CO Correlation Plot (Some discrepancies may arise from the estimated constant time shift arbitrarily applied to the BAe data)
Future Work • Consider differences in measurements and data treatment procedures • Incorporate error bars for all data sets • Archive trace gas intercomparison conclusions on T-REX website
G-V: Buck 1011C (red) BAe146: GE 1011B (blue) G-V Chilled Mirror: Buck 1011C (blue) G-V Laser Hygrometer: Maycomm (red)
G-V Chilled Mirror: Buck 1011C (blue) G-V Laser Hygrometer: Maycomm (red)
Future Work • Determine altitude-dependent time constant of G-V chilled mirror hygrometer • Quantify accuracy of calibration at low levels of water vapor • Reference hygrometer measures a condensation temperature • Conversion to a mixing ratio can be a big source of uncertainty
From Murphy and Koop, QJRMS, 2005 Theoretical Parameterizations Observations
O3 Correlation Plot: Segmented by Altitude (Some discrepancies may arise from the estimated constant time shift arbitrarily applied to the BAe data) Note: Altitude segments are depicted in slide 3.
Difference in the O3 measurements (BAe vs. GV) (Some discrepancies may arise from the estimated constant time shift arbitrarily applied to the BAe data)
Difference in the CO measurements (BAe vs. GV) (Some discrepancies may arise from the estimated constant time shift arbitrarily applied to the BAe data)