Search Results

You are looking at 1 - 8 of 8 items for :

  • Regional effects x
  • NOAA/EPA Golden Jubilee x
  • All content x
Clear All
Edith Gégo, P. Steven Porter, Alice Gilliland, and S. Trivikrama Rao

anthropogenic emissions would affect the intraday and diurnal variations of ozone, pointing to a high degree of local control. More important to us, they showed that reducing emissions from large elevated point sources has a limited effect on short-term time scales but has substantial effects at longer time scales (synoptic and longer), pointing to a regional control of ozone variations (i.e., pollution transport–based control). Following the results of Hogrefe et al. (2000) , we calculated the standard

Full access
Ho-Chun Huang, Xin-Zhong Liang, Kenneth E. Kunkel, Michael Caughey, and Allen Williams

1. Introduction Human activities have led to several important air quality issues, such as elevated tropospheric ozone (O 3 ), particulate matter, and visibility problems, which affect human health and the natural environment. Anthropogenic increases in atmospheric concentrations of greenhouse gases also are increasing concerns about future climate change ( Houghton et al. 2001 ). Global warming could have detrimental effects on future air quality, such as increased frequency of harmful

Full access
M. Talat Odman, Yongtao Hu, Alper Unal, Armistead G. Russell, and James W. Boylan

dust, construction, grinding, and agriculture), and it is formed in the atmosphere through chemical transformation of precursor gases. It can travel long distances and affect very large geographic areas. In certain parts of the United States the visual range has been reduced considerably from natural conditions. Visibility is a measure of the clearness of the atmosphere. Regional haze is the impairment of visibility caused by the presence of PM in the atmosphere and is usually expressed in term of

Full access
Armin Aulinger, Volker Matthias, and Markus Quante

1. Introduction Polycyclic organic hydrocarbons (PAHs) belong to the so-called persistent organic pollutants (POPs), a group of substances with known adverse effects on ecosystems and human health. Single ones or mixtures of these compounds can, for example, cause cancer or impair reproduction ( Mumatz and George 1995 ). The concentrations of PAHs in the environment are relatively low, but they gain their extraordinary ecotoxicity from their persistency in various environmental compartments

Full access
George Kallos, Marina Astitha, Petros Katsafados, and Chris Spyrou

-pollution modeling techniques, together with air-quality observations. Some key issues concerning the knowledge of the air-quality status in the Euro-Mediterranean region are the identification of the geographic distribution of pollutant sources and the regional climatological description for the GMR. The PM levels and composition and European Union (EU) policies addressing PM levels should be kept in mind and are hence briefly discussed herein. Paths and scales of transport and transformation of air pollution

Full access
John S. Irwin, William B. Petersen, and Steven C. Howard

envisioned as (adapted from Venkatram 1988 ) where α are the model input parameters, β are the variables needed to describe the unresolved transport and dispersion processes, the overbar represents an average over all possible values of β for the specified set of model input parameters α , c (Δ c ) represents the effects of measurement uncertainty of the concentration values, and c ″( α , β ) represents our ignorance of β (unresolved deterministic variations and stochastic fluctuations

Full access
Francis S. Binkowski, Saravanan Arunachalam, Zachariah Adelman, and Joseph P. Pinto

that total surface irradiance is output rather than actinic flux because irradiance is more appropriate than actinic flux for CMAQ applications that examine the potential effects of changes in UV radiation in response to changes in concentrations of gaseous and aerosol species. Stratospheric ozone column amount is modeled using the method of Van Heuklon (1979) . Michalsky et al. (1995) have shown that this approach might yield column amounts that are too high and may need to be scaled to a lower

Full access
C. Hogrefe, W. Hao, K. Civerolo, J.-Y. Ku, G. Sistla, R. S. Gaza, L. Sedefian, K. Schere, A. Gilliland, and R. Mathur

severe overpredictions during the early morning and evening hours. CMAQ predictions have a pronounced double-peak structure that is either not present at all (sulfate, OM) or much weaker (nitrate, EC) in the observations. In contrast to the other species investigated here, EC does not have a secondary formation mechanism, that is, ambient concentrations are determined by the combined effects of emissions, horizontal and vertical transport, and deposition. To investigate which of these processes may

Full access