HR: 1340h
AN: A23A-0765    [Abstracts]
TI: Simultaneous Measurement of NO$_{2}$, NO$_{3}$ and N$_{2}$O$_{5}$ by Cavity Ring-down Spectroscopy During NEAQS-ITCT 2004
AU: * Osthoff, H D
EM: hosthoff@al.noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: * Osthoff, H D
EM: hosthoff@al.noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, CO 80309 United States
AU: Brown, S S
EM: sbrown@al.noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Brown, S S
EM: sbrown@al.noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, CO 80309 United States
AU: Pettersson, A
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Pettersson, A
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, CO 80309 United States
AU: Baynard, T
EM: tbaynard@al.noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Baynard, T
EM: tbaynard@al.noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, CO 80309 United States
AU: Dub‚, W P
EM: bdube@al.noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Dub‚, W P
EM: bdube@al.noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, CO 80309 United States
AU: Lerner, B
EM: brian.lerner@noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Williams, E
EM: eric@al.noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Ravishankara, A R
EM: a.r.ravishankara@noaa.gov
AF: National Oceanic and Atmospheric Administration, Aeronomy Laboratory 325 Broadway, Boulder, CO 80305 United States
AU: Ravishankara, A R
EM: a.r.ravishankara@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado , Boulder, CO 80309 United States
AU: Ravishankara, A R
EM: a.r.ravishankara@noaa.gov
AF: Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309 United States
AB: We have constructed a cavity ring-down spectrometer (CaRDS) for the simultaneous measurement of nitrogen dioxide, NO$_{2}$, nitrate radical, NO$_{3}$, and dinitrogen pentoxide, N$_{2}$O$_{5}$, in the atmosphere. NO$_{3}$ is known to be the primary nighttime oxidant; during the day, NO$_{3}$ is efficiently destroyed by photolysis. N$_{2}$O$_{5}$ removal is a major pathway for loss of NO$_{x}$, a key ozone production ingredient, from the troposphere. The instrument employs three cavity ring-down cells. In the first cell, NO$_{2}$ is monitored at 532 nm using a frequency-doubled Nd-YAG laser operated in pulsed mode at 100 Hz. In the second channel, the ambient NO$_{3}$ radical concentration is measured at 662 nm, using the output of a dye laser. The third channel is heated to $75\deg$C, which quantitatively converts N$_{2}$O$_{5}$ to NO$_{3}$, and the amount of N$_{2}$O$_{5}$ present is then determined from the increase in the absorption signal at 662 nm. Detection limits are $<1$ pptv for NO$_{3}$ and N$_{2}$O$_{5}$ and 35 pptv for NO$_{2}$ (1 s averages). With this instrument, it becomes possible to continuously characterize all the key nitrogen species involved in NO$_{3}$/N$_{2}$O$_{5}$ chemistry with high precision directly in the atmosphere. The spectrometer was fielded during the NEAQS-ITCT 2004 campaign on board of the research vessel Ron Brown. In this presentation, we compare our CaRDS NO$_{2}$ to that measured using the more traditional method and present some initial findings from this campaign, with particular emphasis on the chemical evolution of NO$_{x}$ species in NO$_{x}$-rich urban plumes in the marine boundary layer.
DE: 0325 Evolution of the atmosphere
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting