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CHARACTERIZATION OF THE SPATIOTEMPORAL VARIABILITY OF NON-URBAN OZONE CONCENTRATIONS OVER THE EASTERN UNITED STATES
Citation:
Eder, B., J. Davis, AND P. Bloomfield. CHARACTERIZATION OF THE SPATIOTEMPORAL VARIABILITY OF NON-URBAN OZONE CONCENTRATIONS OVER THE EASTERN UNITED STATES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/489 (NTIS PB94130259).
Description:
The spatial and temporal variability of the maximum 24 hourly 03 concentrations over non-urban areas of the eastern United States was examined for the period 1985-1990 using principal component analysis. tilization of Kaiser's Varimax orthogonal rotation led to the delineation of six contiguous subregions (together accounting for 64.02% of the total variance), which each displayed statistically unique 03 characteristics. xamination of these characteristics revealed that when compared to the entire domain, the Mid-Atlantic and South Subregions observe higher ozone concentrations. oncentrations are near the domain average for the Northeast and Southwest Subregions and are lowest in the Great Lakes and Florida Subregions. he percentage of observations exceeding 120 ppb were greatest in the Mid-Atlantic and Southwest Subregions, near the domain average in the Northeast and South Subregions and lowest in the Great Lakes and Florida Subregions.Examination of the time series of the principal component scores associated with the Subregions indicated that the Great Lakes, Northeast, South and Mid-Atlantic Subregions all exhibit a seasonality characterized by higher concentrations during the period from June through August. he Great Lakes and Mid-Atlantic Subregions tend to observe a stronger seasonal cycle, with maximum concentrations occurring during the last week in June and the first week in July, respectively. he strength of this seasonality is weakened for the Northeast and South Subregions and its timing delayed, until the end of July and the first of August, respectively. he Southwest Subregion experiences a greatly diminished seasonality, with maximum concentrations delayed until the middle of August. he seasonality found in the Florida Subregion is unique in both its strength and timing, as the highest concentrations consistently occur during the months of April and May. he time series were then deseasonalized and autocorrelations and spectral density estimates calculated, revealing that persistence is much more prevalent in the Florida (autocorrelation significant to a lag of 4 days), South (3 days) and Southwest (3 days) Subregions. onversely, autocorrelations are only significant to a lag of one day in the Northeast and two days for the Great Lakes and Mid-Atlantic Subregions. nnually, the highest concentrations generally occurred in 1988; however, the Southwest and Florida Subregions recorded equally high concentrations in other years. o one other year stood out statistically across all subregions. rends analyses indicated a slight. though not statistically significant, decrease in moon concentrations for the Mid-Atlantic, Northeast and Southwest Subregions and a slight increase over the Great Lakes, South and Florida Subregions.