Comment on: “The measurement of tropospheric OH radicals by laser‐induced fluorescence spectroscopy during the POPCORN Field Campaign” by Hofzumahaus et al. and “Intercomparison of tropospheric OH radical measurements by multiple folded long‐path laser absorption and laser induced fluorescence” by Brauers et al.
1997; American Geophysical Union; Volume: 24; Issue: 23 Linguagem: Inglês
10.1029/97gl02899
ISSN1944-8007
AutoresE. J. Lanzendorf, T. F. Hanisco, Neil M. Donahue, P. O. Wennberg,
Tópico(s)Atmospheric and Environmental Gas Dynamics
ResumoCalibration of laser induced fluorescence (L•) instruments that measure OH is challenging because it is difficult to reliably introduce a known amount of this reactive radical into a measurement apparatus.In a recent paper, Hofzumahaus et al., [1996] describe a novel and seemingly simple technique to accomplish this goal: they dissociate trace quantities of water vapor in air with a low pressure mercury (Hg) lamp to 5 9 -3 produce low concentrations (10 -10 cm ) of OH (R1).The lamp fluence is then calibrated by ozone actinometry (R2): H 20 + hv (1849.5 • --> OH + H (R 1 ) 0 2+hv(1849.5••O+O O + 0 2 --> 0 3 .(R2) The OH concentration is inferred from the ambient water vapor and 02 mixing ratios, the measured 03 concentration, and the relevant cross sections: [OH]= 0.H20 [H20][O3 ] (EQ1) 20'02 [0 2 ] In Brauers et al., [1996], an OH measurement calibrated
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