the horizontal/vertical resolution considered. For PM2.5 nonattainment applications where large

spatial gradients of primary PM2.5 exist, a dispersion model may be needed in addition to a

photochemical model.

4. Select appropriate meteorological time periods to model. Like the preceding step, this

step requires review of available air quality and meteorological data. It also requires a thorough

understanding of the form of the ozone and PM2.5 NAAQS, the regional haze goals, and the

modeled attainment tests described in Sections 3-6. Finally, it requires a review of

meteorological conditions which represent annual PM2.5 concentrations, both good and bad

visibility days, and time periods which have been observed to accompany monitored

exceedances of the 8-hour ozone or 24-hour PM2.5 NAAQS. The object of these reviews is to

select periods which a) include days with observed concentrations exceeding site-specific design

values (8-hour ozone or 24-hour PM2.5 NAAQS), b) select a representative mix of days for each

quarter in applications dealing with the annual NAAQS and/or c) select days which are

representative of those corresponding with good and poor visibility.

Due to increased computer speeds, it is now prudent to recommend modeling relatively

long time periods. For 8-hour ozone and 24-hour PM2.5, at a minimum, modeling episodes which


n751 - n752 - n753 - n754 - n755 - n756 - n757 - n758 - n759 - n760 - n761 - n762 - n763 - n764 - n765 - n766 - n767 - n768 - n769 - n770 - n771 - n772 - n773 - n774 - n775 - n776 - n777 - n778 - n779 - n780 - n781 - n782 - n783 - n784 - n785 - n786 - n787 - n788 - n789 - n790 - n791 - n792 - n793 - n794 - n795 - n796 - n797 - n798 - n799 - n800


   Flag of Portugal 


 castellano: DISPER CUSTIC DESCAR RADIA    italiano:     


 français:    português:  






deutsch: DIS CUS  DES  RAD

castellano: DIS CUS DES  RAD   english: DIS CUS DES RAD  


 português: DIS CUS DES RAD   italiano:   DIS CUS  DES RAD


français:  DIS CUS DES RAD