Simulating isoprene oxidation in GFDL AM3 model Jingqiu Mao (NOAA GFDL), Larry Horowitz (GFDL),...
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Simulating isoprene oxidation in GFDL AM3 model Jingqiu Mao (NOAA GFDL), Larry Horowitz (GFDL), Vaishali Naik (GFDL), Meiyun Lin (GFDL), Arlene Fiore (Columbia
Simulating isoprene oxidation in GFDL AM3 model Jingqiu Mao
(NOAA GFDL), Larry Horowitz (GFDL), Vaishali Naik (GFDL), Meiyun
Lin (GFDL), Arlene Fiore (Columbia U) Funding from NOAA CPO
Slide 2
Summertime ozone over eastern US is a 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 Standard AM3 (Naik et al., 2013, JGR, in press)
Slide 3
A new isoprene chemistry for global models (Mao et al.,
submitted to JGR) ISOPO2 + NO is based on Paulot et al. (2009,
ACP). ISOPO2 + HO2 is based on Paulot et al. (2009, Science).
Isomerization of ISOPO2 is based on Peeters et al. (2009, PCCP) and
Crounse et al. (2011, PCCP). How fast is the isomerization?
Slide 4
Was OH really that high over SE US during ICARTT? (Ren et al.,
2008, JGR) OH measured by traditional method during ICARTT 2004
(Mao et al., 2012, ACP) Part of OH signal could be due to
interference, probably from Criegee Intermediate! A new method of
measuring OH was deployed in Blodgett Forest
Slide 5
First generation of isoprene nitrates degraded to second
generation nitrates! Second generation isoprene nitrates (C3-C4)
First generation isoprene nitrates (C5) C5 alkyl nitrate is
short-lived due to oxidation by OH and ozone, with photochemical
lifetime of 2-3 hrs. Consistent with measurements from Thorntons
group, C5
Nighttime chemistry Based on Rollins et al. (2009) and Xie et
al. (2012) Nighttime yield of organic nitrates is 70%>>
daytime yield (11.7%)
Slide 7
This chemistry was implemented in GEOS-Chem Ozone in the
boundary layer during ICARTT 2004 Observations Model Obs vs. Model
Improved O 3 -CO correlations due to: 1.Recycling of NO x from
isoprene nitrates 2.HO 2 uptake (lower OH and increase NO x
lifetime). (Mao et al., submitted to JGR)
Slide 8
Mean vertical profiles during ICARTT O 3 has no bias in
boundary layer and free troposphere. HCHO provides good constraint
on isoprene emissions. Observations Model (GEOS-Chem) (Mao et al.,
submitted to JGR)
Slide 9
Total organic nitrates excluding peroxyacylnitrates (ANs) Model
well reproduced ANs. ANs is dominated by secondary organic nitrates
(C3-C4). ANs vs. HCHOANs vs. O 3 Model well reproduced ANs vs. HCHO
and ANs vs. O 3 correlations. These correlations cannot be
reproduced by a fast isomerization channel of ISOPO 2. Vertical
profiles Speciation of ANs
Slide 10
NO y budget in eastern U.S. boundary layer for July 2004
SpeciesEmission Chemical (P-L) Dry Deposition Wet Deposition Net
Export NO x 386-33744------5 PANs 2413------11 ANs ANs 187.43.67 R
4 N 2 100.5-------10 HNO 3 277180110-3 Export of ANs > Export of
PANs
Slide 11
New chemistry Previous studies without NO x recycling Current
anthro NO x emissions (2004) Reduce current anthro NO x emissions
by 50% Isoprene NO x OH O 3 due to O 3 +ISOP Surface ozone response
to isoprene emissions NO x emissions Sensitivity of ozone to
isoprene emissions
Slide 12
GFDL AM3 configuration for SENEX Fully coupled
chemistry-climate model o Parameterizes aerosol activation into
liquid cloud droplets o solves both tropospheric and stratospheric
chemistry over the full domain Nudging wind with GFS meteorological
field High resolution (50 x 50 km) and coarse resolution (200 x 200
km) MEGAN biogenic emissions Anthropogenic emissions use RCP 8.5
scenario (0.5 x 0.5 degree) New isoprene chemistry (Mao et al.,
submitted to JGR) New heterogeneous chemistry (Mao et al., 2013a,
ACP; 2013b, GRL) C48 (200 x 200km) C180 (50 x 50km) Monthly mean
ozone for July of 2012
Slide 13
Updated chemistry Standard AM3 Observations CASTNET sites
Slide 14
Improvement on ozone over SE US (Naik et al., 2013, JGR, in
press) Bias is reduced from 12.9 ppbv to 3.3 ppbv. This should be
reexamined by MDA8 ozone. Model tends to overestimate monthly mean
ozone. Standard AM3 New chemistry in AM3
Slide 15
Sunrise Entrainment zone Model shows large amount of VOCs and
OVOCs in the residual layer. Is it possible to do a early morning
flight to see the entrainment zone? Boundary layer structure by
Stull (1988). Does nighttime chemistry affect global nitrogen/ozone
budget? Sunset
Slide 16
HCHO yield at different NO x conditions Computed in a
photochemical box model. Initialized with 1ppb isoprene. O 3
(40ppb), CO (100ppb), and NO x are held constant. Prompt HCHO
formation, important for deriving isoprene emission from satellite
observations. Yield of HCHO is lower at lower NO x concentrations,
according to the model. But the model could be wrong!
Slide 17
Next step: merging in-cloud SOA module with new isoprene
chemistry (Ford et al., 2013, ACPD) A new module of in-cloud SOA
production developed in AM3 (Liu et al., 2012, JGR)
Slide 18
(Lamsal et al., 2010) Surface NO x emissions >> other
emissions above the surface. 10% leak of surface NO x will double
the effect of lightning. Surface NO x ventilation will be critical
for NO x /ozone in free trop