HR: 1340h
AN: A13C-0930    [Abstracts]
TI: Hydroperoxy Radical Flux Measurements Using the LIF Detection Technique With the Eddy-Covariance Method
AU: * Naik, C V
EM: cvn1@psu.edu
AF: Department of Meteorology, Pennsylvania State University, 503 Walker Building, University Park, PA 16802 United States
AU: Brune, W H
EM: brune@ems.psu.edu
AF: Department of Meteorology, Pennsylvania State University, 503 Walker Building, University Park, PA 16802 United States
AB: The hydroperoxy radical (HO₂) is an important radical for the NOx-ozone photochemistry in the troposphere. Because of the rapid chemical exchange with the hydroxyl radical (OH), HO₂ mixing ratios depend on the production and losses of both OH and HO₂. The typical atmospheric lifetime of HO₂ is on the order of few minutes, which is comparable to eddy transport times near the surface. Thus, surface deposition of HO₂ could be another potential loss. To understand the exchange of HO₂ in the surface layer, eddy fluxes of HO₂ have been measured about 5 m above the ground at Rock Springs near State College, PA. The laser induced fluorescence (LIF) technique was used to measure HO₂ concentrations at 5 Hz. Commercial three dimensional sonic anemometer (CSAT3) was used to measure wind speed and virtual temperature. Eddy-covariance method is used to determine the fluxes. Power spectra of HO₂ mixing ratios follow the -5/3 law reasonably well, indicating good data quality. Preliminary analysis shows that during day time, typical HO₂ flux is on the order of 10^-6 μmol/m²s, and tends to be downward, indicating deposition. At night, even when HO₂ mixing ratios are above detectable limits of the instrument, the HO₂ flux approaches zero. These first measurements of HO₂ flux and their implications for understanding the exchange of HO₂ in the surface layer will be presented.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005