The impact ofmeteorological persistence on the distribution and extremes of ozone

CASTNET (Clean Air Status and Trends Network) ozone and temperature data and large-scale meteorological analysis are used to quantify the extent to which meteorological events and their persistence impact ozone with an emphasis on the high end of the ozone distribution (greater than the 90th percentile). Ozone increases with each successive stagnation day in all regions of the U.S., with the highest increase in the Northeastern U.S. (0.4 standard deviation or similar to 4.7 ppb per successive stagnation day). Ozone increases with days since cyclone passage only in the Northeastern and Mid-Atlantic regions of the U.S., but on average not enough to reach the 90th percentile concentration. Persistent high temperature does not result in further ozone increases in any region. On the interannual timescale there is little evidence that summers with large numbers of the above events increase ozone preferentially on the high end of the ozone distribution.