HR: 0830h
AN: A51E-0730    [PDF]
TI: Quantification of Ozone Formation Metrics in Southeastern New Hampshire During NEAQS 2002
AU: * Griffin, R J
EM: rob.griffin@unh.edu
AF: University of New Hampshire, EOS Morse Hall 39 College Road, Durham, NH 03824 United States
AU: Johnson, C
EM: caj42@uchicago.edu
AF: University of New Hampshire, EOS Morse Hall 39 College Road, Durham, NH 03824 United States
AB: Ozone formation metrics are calculated using ambient measurements taken during NEAQS 2002 at the Thompson Farm sampling station in rural southeastern New Hampshire. The metrics include the O3 production rate (OPR), O3 production efficiency (OPE), and reactivity (R). OPR is calculated as the rate of formation of peroxy radicals or the rate of conversion of NO to NO2. In each method, the rate calculated is assumed to be the rate-limiting step in O3 formation. OPR values illustrate the relative importance of chemical and transport mechanisms in leading to peaks in O3. OPE is defined as the ratio of the OPR to the rate of loss of NOx (assumed to be the HNO3 formation rate) and demonstrates the moles of O3 formed per mole of NOx emitted. A second method for calculating OPE gives a temporally averaged OPE by regressing O3 mixing ratios against NOy-NOx. Lastly, individual R values indicate the time scale for peroxy radical formation from reactions between CO or other reactive organic gases (ROGs) and OH. R for an individual gas is the product of its mixing ratio and reaction rate constant with OH. Total R is the sum of the individual values. Mixing ratio data for NO, NOy, O3, and CO are collected at 1-minute resolution. Temperature and jNO2 are also measured at 1-minute resolution. However, ten-minute averages of these parameters are used to coincide with ten-minute averages of ROG mixing ratios measured once per hour. Only data that coincide with sufficient sunlight intensity to ensure the photostationary state are used. A zero-dimensional version of a photochemical mechanism is used to estimate mixing ratios of relevant HOx radicals. Results show OPR and R values that are very low compared to other locations. OPR peaks during midday. R peaks earlier and later in the day and tends to be dominated by short-chain hydrocarbons. The low values of OPR indicate that peaks of O3 in this location are likely a result of the mixing of O3-rich air transported from higher levels of the atmosphere or other areas. The relatively high OPE values for this location confirm that the air in southeastern New Hampshire is typically NOx-limited.
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting