HR: 0800h
AN: A31B-0056    [Abstracts]
TI: The Distribution of Molecular Hydrogen in the Lower Troposphere
AU: * Novelli, P C
EM: Paul.C.Novelli@noaa.gov
AF: Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Lang, P M
EM: Patricia.M.Lang@noaa.gov
AF: Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Masarie, K A
EM: Kenneth.A.Masarie@noaa.gov
AF: Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AB: The National Oceanic and Atmospheric Administration, Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) has measured the distribution of molecular hydrogen using a cooperative air sampling network since the early 1990s. The global H$_{2}$ distribution and budget were examined by Novelli et al. (JGR, 104, 30427, 1999) using network data through 1997. Here we expand on the earlier paper to examine effects of the 1997/1998 wildfires on H$_{2}$ distributions, evaluate its decadal changes, and review the H$_{2}$ budget in terms of coincident measurements with carbon monoxide (CO). While CO and H$_{2}$ share many common sources, CO is predominately destroyed through reaction with OH while H$_{2}$ has a strong soil sink. Both gases exhibited anomalously high mixing ratios in 1998 which we attribute to emissions from extensive tropical and boreal wildfires. Despite their common sources, correlations between CO and H$_{2}$ were only significant during the northern winter and early spring. This relationship reflects their anthropogenic source combined with the absence of a significant sink. From a globally smoothed surface we extracted estimates of decadal changes in hydrogen. Average rates of change between 1992 and 2003 were small [$\pm$ 0.5 ppb yr$^{-1}$ or less ($<$ 0.1% yr$^{-1}$)] but showed both seasonal and latitudinal features. The eleven year time series showed greatest rates of change in the high latitudes of the Northern Hemisphere during winter. The changes tended to be negative in the Northern Hemisphere while slightly positive in the extra-tropical and polar Southern Hemisphere. These changes are discussed in terms of the distribution of H$_{2}$ sources and sinks.
UR: http://www.cmdl.noaa.gov/ccg/index.html
DE: 0315 Biosphere/atmosphere interactions
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting