Ozone and organic nitrates over the eastern US: sensitivity to isoprene chemistry Jingqiu Mao (NOAA GFDL) , Fabien Paulot (Harvard), Daniel Jacob (Harvard), Ronald Cohen (UC Berkeley), John Crounse (Caltech), Paul Wennberg (Caltech), Christoph Keller (Harvard), Rynda Hudman (EPA), Michael Barkley(U Leicester), Larry Horowitz (NOAA GFDL)
14
Embed
Ozone and organic nitrates over the eastern US: sensitivity to isoprene chemistry
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Ozone and organic nitrates over the eastern US:sensitivity to isoprene chemistry
Jingqiu Mao (NOAA GFDL), Fabien Paulot (Harvard), Daniel Jacob (Harvard), Ronald Cohen (UC Berkeley), John Crounse (Caltech), Paul Wennberg (Caltech), Christoph Keller (Harvard), Rynda Hudman (EPA), Michael Barkley(U Leicester), Larry Horowitz (NOAA GFDL)
Summertime ozone over eastern US is a classic problem for most models
(Fiore et al., 2009, JGR)
Multimodel mean
Obs from CASTNET surface sites
Northeast US
Southeast US
Multimodel mean
Obs from CASTNET surface sites
We didn’t have this problem during ICARTT!
(Hudman et al., 2007, JGR)
DC-8 ozone
WP-3D ozone
NO
12
34
OH
11.7%
O
MVK
First generation isoprene nitrates
O
MACRH
O
H
HCHO
88%Organic peroxides
OHOO
OO
OH
-hydroxyl peroxy radicaland isomers
-hydroxyl peroxy radicaland isomers
79% 21%
HO2 1,6-H shif t isomerization
4.7%
7.3%
12%26% 40% 66%
HOOO
HPALDs
hvOH100%
100%
C2 and C3 carbonyl compounds
ISOPO2 ISOPO2
Switching to Fabien’s isoprene chemistry
(1) smaller yield of isopreneNitrate (IN)
(2) IN is not a terminal sink!
OH
ONO2
ISOPN (1,4)
OHONO2
ISOPN (1,2)
OHONO2
ISOPN (4,3)
ONO2
OH
ISOPN (4,1)
O
OH
ONO2
methylvinylketone nitrate (MVKN)
O2NO O
ethanal nitrate(ETHLN)
O2NO
O
propanone nitrate(PROPNN)
O
methacrolein nitrate(MACRN)
ONO2
OH
OH/O2
OH
ONO2
OHOO
NO
OH
ONO2
OHO
OHONO2
OHOO
NO
OHONO2
OHO
ONO2
OH
OHOO
NO
ONO2
OH
OHO
OHONO2
OHOO
NO
OHONO2
OHO
OH/O2OH/O2OH/O2
First generation of isoprene nitrates degraded to second generation nitrates!
NOx recycling efficiency is 55%!
Ozone bias is about +5 ppb in both boundary layer and free troposphere!
ObsStd chem (v8-2-3)Paulot isoprene chem
Surface
500 hPa
A few more updates (impact on July afternoon ozone of 2004)
(Mao et al., ACP 2013) Implemented by Christoph Keller
(Parrella et al., ACP 2012)
We are now in good shape...
Ozone in the boundary layer during ICARTTObservations Model
Obs vs. ModelImproved O3-CO correlations due to:1. Recycling of NOx
from isoprene nitrates
2. HO2 uptake (lower OH and increase NOx lifetime).
Mean vertical profiles during ICARTT
O3 has no bias in boundary layer and free troposphere.HCHO provides good constraint on isoprene emissions.
ObservationsModel (this work)
Total organic nitrates excluding peroxyacylnitrates (∑ANs)
Model well reproduced ∑ANs.
∑ ANs is dominated by secondary organic nitrates.
∑ANs vs. HCHO ∑ANs vs. O3
Model well reproduced ∑ANs vs. HCHO and ∑ANs vs. O3 correlations.
These correlations cannot be reproduced by a fast isomerization channel of ISOPO2.
Vertical profiles Speciation of ∑ANs
NOy budget in eastern U.S. boundary layer for July 2004