16 the modeling system (Bergin et al., 2008). Sensitivity coefficients relating source emissions to

17 air quality are estimated during the model simulation and output at the resolution of the

18 photochemical grid model. An important difference between source apportionment and source

19 sensitivity is that source apportionment answers the “contribution” question, “How much did a

20 source contribute overall to modeled air quality?” and source sensitivity answers the

21 “responsiveness” question, “How will modeled air quality change if the source’s emissions

15 Several photochemical grid modeling approaches that allow for estimation of the secondary PM2.5 impacts from a

proposed new or modifying source were presented during the Emerging Models / Techniques Session of the 10th

Modeling Conference. Additional information regarding and presentations from the 10th Modeling Conference can

be found on the SCRAM website at: http://www.epa.gov/ttn/scram/10thmodconf.htm.

III.2.3.3 Sub-grid Plume Treatment in Photochemical Grid Models

4 In some instances where the source and critical receptors are in very close proximity, the

5 source and receptors may be located in the same photochemical grid model cell. Since physical

6 and chemical processes simulated in the model represent a volume average, this may not

7 adequately (or appropriately) represent the gradients of pollution that may exist between the

8 source and receptors. One approach to more explicitly represent the spatial gradient in source9

receptor relationships when they are in close proximity would be to use smaller sized grid cells.

10 Grid resolution would be defined such that the source and receptors are no longer in the same

11 grid cell. Ideally, there would also be several grid cells between the source and receptors to best

12 resolve near-source pollution gradients.

13 In these situations of close proximity


n451 - n452 - n453 - n454 - n455 - n456 - n457 - n458 - n459 - n460 - n461 - n462 - n463 - n464 - n465 - n466 - n467 - n468 - n469 - n470 - n471 - n472 - n473 - n474 - n475 - n476 - n477 - n478 - n479 - n480 - n481 - n482 - n483 - n484 - n485 - n486 - n487 - n488 - n489 - n490 - n491 - n492 - n493 - n494 - n495 - n496 - n497 - n498 - n499 - n500



   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