HR: 0800h
AN: A11C-0604    [Abstracts]
TI: Inter-annual Variations in CO as Seen at the Mt. Bachelor Observatory by Satellites, GEOS- Chem and Other Regional Surface Sites
AU: * Reidmiller, D R
EM: dreidm@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences, Box 351640, Seattle, WA 98195, United States
AU: Jaffe, D
EM: djaffe@u.washington.edu
AF: University of Washington - Bothell, Department of Interdisciplinary Arts & Sciences, 18115 Campus Way NE, Bothell, WA 98011, United States
AU: Novelli, P C
EM: paul.c.novelli@noaa.gov
AF: National Oceanographic & Atmospheric Administration, Earth Science Research Laboratory (ESRL), Global Monitoring Division (GMD), 325 Broadway, Boulder, CO 80303, United States
AU: Emmons, L
EM: emmons@ucar.edu
AF: National Center for Atmospheric Research, Atmospheric Chemistry Division, 3450 Mitchell Lane, Boulder, CO 80301, United States
AU: Zhang, L
EM: linzhang@fas.harvard.edu
AF: Harvard University, Department of Earth & Planetary Science, 29 Oxford St, Cambridge, MA 02138, United States
AB: Inter-annual variations in tropospheric trace gases are caused by variations in emissions (especially fires), variations in transport, OH, or other causes. Understanding this variability is essential for air quality regulation and attribution. We have made continuous measurements of O₃, CO, sub-micron σ_sp (aerosol scattering coefficient), NO_y, total airborne Hg and various meteorological parameters at the Mt Bachelor Observatory (MBO: 43.98°N, 121.69°W; 2.7 km ASL) since Feb 2004. These measurements, along with MOPITT satellite retrievals, GEOS-Chem chemical transport model output and 4 western U.S. NOAA ESRL/GMD surface sites all show the highest springtime (April) CO maximum from 2004-07 occurred in 2005. The April mean CO maximum reached 188 ppbv in 2005 at MBO. In 2006 and 2007, the April maximum was lower at ~145 ppbv (a 24% decline from 2005). This decrease, albeit on the order of 5-10 ppbv, was also observed in: MOPITT CO retrievals at 700 mb (a 5% decline from 2005 to 2006+07), GEOS-Chem output for the MBO region (a 7% decline), as well as at four ESRL/GMD sites in the western U.S (a 7% decline). We attempt to answer the following questions: 1) Why was the April CO maximum significantly higher in 2005 compared to 2006 and 2007?, and 2) Why is the decline from 2005 to 2006+07 so much greater at MBO than in the other platforms and model output? We analyze remotely sensed fire counts throughout the Northern Hemisphere to examine the role of biomass burning. We compile a climatology of backtrajectories from MBO to investigate the variability of meteorological transport conditions. We have also observed a steady decline in the late summer CO minimum at MBO from 2004-07 when all data are considered. We present several methodologies for segregating MBO data (e.g., NO_x cycles, water vapor and O₃ patterns, etc.) in an effort to understand the upslope / downslope flow at our mountain site on both diurnal and seasonal timescales. This has direct implications for the influence the regional BL (i.e., local wildfires) has on measurements at MBO and may provide insight into this decrease in the late summer CO minimum.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0368 Troposphere: constituent transport and chemistry
DE: 0438 Diel, seasonal, and annual cycles (4227)
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting