HR: 1330h
AN: A32A-0123    [PDF]
TI: HO$_x$ Radical Measurements During the ECHO Field Campaign in Summer 2003
AU: Hofzumahaus, A
EM: a.hofzumahaus@fz-juelich.de
AF: Institut fuer Chemie und Dynamik der Geosphaere II: Troposphaere Forschungszentrum Juelich, Leo Brandt Strasse, Juelich, D-52425 Germany
AU: * Siese, M
EM: m.siese@fz-juelich.de
AF: Institut fuer Chemie und Dynamik der Geosphaere II: Troposphaere Forschungszentrum Juelich, Leo Brandt Strasse, Juelich, D-52425 Germany
AU: Rupp, L
EM: l.rupp@fz-juelich.de
AF: Institut fuer Chemie und Dynamik der Geosphaere II: Troposphaere Forschungszentrum Juelich, Leo Brandt Strasse, Juelich, D-52425 Germany
AU: Holland, F
EM: f.holland@fz-juelich.de
AF: Institut fuer Chemie und Dynamik der Geosphaere II: Troposphaere Forschungszentrum Juelich, Leo Brandt Strasse, Juelich, D-52425 Germany
AU: Schlosser, E
EM: e.schlosser@fz-juelich.de
AF: Institut fuer Chemie und Dynamik der Geosphaere II: Troposphaere Forschungszentrum Juelich, Leo Brandt Strasse, Juelich, D-52425 Germany
AB: Atmospheric OH and HO$_2$ radical concentrations were measured during a field campaign in July 2003 in a forest in Juelich, Germany. The campaign was part of the ECHO project which investigates the emission and chemical processing of biogenic volatile organic compounds (VOC) in and above a mixed forest stand, in order to derive improved estimates of net emissions of biogenic compounds and their possible degradation products into the planetary boundary layer. The OH radicals, which can provide a major sink for VOCs, were detected directly by laser-induced fluorescence (LIF) at 308 nm. The HO$_2$ radicals, which can result from reactions of VOCs with radicals like OH or NO$_3$, were measured by LIF following the conversion of HO$_2$ into OH by reaction with NO. During the campaign, a newly developed LIF instrument was deployed which is much more compact and light weighted than the instrument previously used by our group. The relatively small size of the new instrument (foot-print 150 x 70 cm) allowed to place the instrument on a movable platform that could be lifted up and down along a 38 m high tower which was set up in the forest. On the same tower, a comprehensive set of meteorological parameters and other trace gases ( NO$_3$, O$_3$, NO$_x$, VOC, HCHO, HONO, PAN, photolysis frequencies etc.) was measured at different heights above ground. The experimental set up was successfully used a) to measure diurnal variations of radicals and trace gases in and above the canopy and at ground in the forest, b) to measure for the first time vertical concentration gradients of OH and HO$_2$ near ground up to 38 m altitude, and c) to detect fast variations of HO$_x$ radical concentrations with an improved time resolution of 5.5 s. During the intensives of the campaign more than 6 diurnal cycles were measured and 14 vertical profiles at day and nighttime were achieved. This contribution presents the experimental set up of the radical measurements during the ECHO campaign and first results from our radical measurements.
DE: 0315 Biosphere/atmosphere interactions
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting