Document ID: EPA-HQ-OAR-2005-0172-0178
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-06-20T04:00Z

Lydia Wegman/RTP/USEPA/US 

05/11/2007 05:04 PM

	

To

rjohansson@omb.eop.gov, Thomas.Grahame@HQ.DOE.GOV

cc

martin.karen@epa.gov, Joseph Pinto/RTP/USEPA/US@EPA,
richmond.harvey@epa.gov, sasser.erika@epa.gov, wegman.lydia@epa.gov

Subject

Responses to Tom's PRB questions

Tom,

Please find attached answers to the questions on PRB that we discussed
yesterday.  I believe that Joe has responded to all of your questions,
Tom, but let us know if we've missed something.   We can plan to discuss
any further questions you have next week. 

I also wanted to note that there is a section of the CAA, section 179B,
that is designed to address the effects of pollution from outside the US
on nonattainment areas.  It has been used a couple of times and is
potentially available to address the kinds of concerns you raised, Tom,
toward the end of our meeting yesterday.  We can also discuss this next
week if you'd like. 

----- Forwarded by Lydia Wegman/RTP/USEPA/US on 05/11/2007 04:57 PM
-----

Joseph Pinto/RTP/USEPA/US 

05/10/2007 06:09 PM

	

To

Lydia Wegman/RTP/USEPA/US@EPA

cc

Karen Martin/RTP/USEPA/US@EPA, Susan Stone/RTP/USEPA/US@EPA, Harvey
Richmond/RTP/USEPA/US@EPA, Ila Cote/RTP/USEPA/US@EPA, Mary
Ross/RTP/USEPA/US@EPA

Subject

Re: Follow up NAAQS questions

1. GEOS -CHEM chemistry. I spoke to Daniel and he confirmed what I
thought. Changes in chemistry show a very small effect on the ozone
budget of about 5 % in ozone production as shown in Figure 5 of the
attached (Wu et al.).  Fiore et al. used version 4.33 of GEOS-CHEM.  As
they note, changes in production are compensated largely by changes in
chemical destruction. Therefore, the changes in PRB ozone are likely to
be less than 5%.  

  2. Can EPA run MOZART? Not in the foreseeable future given the effort
it takes to learn the model architecture and the manpower resources to
run it.  It is being used routinely at NOAA/GFDL and an arrangement
would have to be worked out with them to run it.

6. a) Ozone from Canada and Mexico - Attached are figures sent by Arlene
Fiore showing differences in monthly mean ozone in the afternoon between
a simulation in which only anthropogenic emissions were shut off and one
in which anthropogenic emissions were shut off in Canada, the U.S. and
Mexico.  Note that for the most part, long range transport occurs above
the planetary boundary layer even during episodes, so for cities located
a few hundred km from the borders during conditions conducive to ozone
episodes, the ozone from Canada and Mexico is likely depleted at the
surface compared to that aloft, because of inhibited vertical mixing.
However, for nearby border areas this is not really a consideration and
transport occurs near the surface. 

b) Build-up of ozone precursors during winter. There's data from Ed
Browell of NASA Langley (J. Geophys. Res. 108, no D4, 8369,
doi:10.1029/2001JD001390, 2003) showing that most ozone in spring at mid
to high latitudes comes from tropospheric sources - not the
stratosphere. It appears that during late winter and early spring most
of the precursors are recycled from the U.S. and Canada and then later
in the spring more of it comes from Eurasia. 

7. China - Estimates of the contribution of ozone coming from China (and
East Asia) to the U.S. range from about 4 or 5 ppb on the Pacific Coast
(cf. Trinidad Head data)down to 1 or 2 ppb in the East. These are the
highest values, and are found during spring. Contributions during other
seasons are lower. You can appreciate that this is so by examining this
transport climatology prepared for me by Rudi Husar for 1999. I don't
see a big problem with scaling the contributions by the emissions
increases, provided the overall concentrations are relatively low in
plumes - not 100 ppb, but more like 40 - 50 ppb.

Let me know if I forgot anything.

Joseph Pinto, PhD.

U.S. Environmental Protection Agency

Mailing address:   B-243-01, RTP, NC  27711

Physical address: 109 T.W. Alexander Dr., RTP, NC  27709

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Fax: 919 541-1818