HR: 0800h
AN: A11C-0605    [Abstracts]
TI: The Effect of Synoptic Scale Mountain Meteorology on Nocturnal Peak Ozone Mixing Ratios for Wintertime Conditions
AU: * Stockwell, W R
EM: wstockwell@howard.edu
AF: Dept. of Chemistry, Howard University, 525 College Street, NW, Washington, DC 20059, United States
AU: kim, D
EM: dckim@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
AB: Nocturnal maxima in ozone mixing ratios are commonly observed in mountainous regions including those without strong emission sources of nitrogen oxides. Local photochemistry does not explain the nocturnal ozone maxima in the absence of emissions of nitrogen oxides. Simulations were performed using the on-line coupled meteorological atmospheric chemistry model (MM5-chem) with relatively course resolution to investigate the synoptic scale mechanisms that lead to nocturnal ozone peaks. These studies show that although chemistry is one factor, synoptic scale flows from mountainous terrain in the Sierra-Nevada Mountains can contribute strongly to nocturnal ozone peaks. Synoptic scale mountain waves can cause strong vertical mixing that produces complex structure in the three dimensional wind fields and ozone mixing ratios over the Sierra-Nevada Mountains and the surface ozone mixing ratios are strongly correlated with the vertical wind direction and speed. Higher ozone mixing ratios were found to be associated with stronger downward vertical winds, higher carbon monoxide and NOx mixing ratios, and with air masses of greater photochemical age. These factors often occurred at night and this suggests that synoptic scale transport of ozone was a very major factor for the high ozone mixing ratios found at many of the mountain sites.
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
DE: 6334 Regional planning (1880)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting