HR: 10:20h
AN: A42B-01 INVITED     [Abstracts]
TI: Reexamining HOx measurements from NASA airborne field campaigns: Lessons learned and future needs
AU: * Crawford, J H
EM: James.H.Crawford@nasa.gov
AF: NASA Langley Research Center, Mail Stop 483, Hampton, VA 23681
AU: Olson, J R
EM: j.r.olson@larc.nasa.gov
AF: NASA Langley Research Center, Mail Stop 483, Hampton, VA 23681
AU: Chen, G
EM: Gao.Chen-1@nasa.gov
AF: NASA Langley Research Center, Mail Stop 483, Hampton, VA 23681
AU: Brune, W H
EM: brune@ems.psu.edu
AF: Pennsylvania State University, Department of Meterology, University Park, 16802
AB: The body of airborne HOx (OH and HO2) observations has grown considerably over recent years. Here, we focus on measurements collected during NASA airborne field campaigns. While results from particular campaigns have raised questions, particularly in the upper troposphere, little has been done to examine the current body of data in a single integrated analysis. In trying to establish consistency between data sets, observations are compared with calculations from a single photochemical model with the most recent reaction rates included. Minor corrections have also been applied to some of the earlier HOx measurements to account for the improved understanding of instrument sampling characteristics that has been established over time. Although this work is ongoing, early results have identified airmass heterogeneity as an issue impacting some previous conclusions regarding HOx. Specifically, model calculations based on 1-minute averages for some flight data differ dramatically from results modeled on much shorter time-scales. There is also some indication that bulk statistical approaches to comparing model calculations and measurements may be influenced by the range of solar zenith angle or primary HOx production encountered. Finally, the buffering of HOx abundance against large changes in production and loss indicates the need for improved measurements of other species (e.g., CH2O) that are more sensitive to changes in photochemical conditions. Current progress on these topics will be presented.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting