simulating isoprene oxidation in gfdl am3 model
DESCRIPTION
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. Summertime ozone over eastern US is a problem for most models. Northeast US. Standard AM3. - PowerPoint PPT PresentationTRANSCRIPT
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
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)
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 onPeeters et al. (2009, PCCP) and Crounse et al. (2011, PCCP) .
How fast is the isomerization?
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
71% 29%
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
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
First generation of isoprene nitrates degraded to second generation nitrates!OH
ONO2
ISOPN (1,4)
OHONO2
ISOPN (1,2)
OHONO2
ISOPN (4,3)
ONO2
OH
ISOPN (4,1)
O
OH
ONO2
methylvinylketone nitrate (MVKN)
O
ethanal nitrate(ETHLN)
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
O2NO
O2NO 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 Thornton’s group, C5<< C4.
NO3
ONO2
OO
NO3
ONO2
O
ONO2
O
OH
O2NO
O
R4N2
Nighttime chemistry
Based on Rollins et al. (2009) and Xie et al. (2012)
Nighttime yield of organic nitrates is 70%>> daytime yield (11.7%)
This chemistry was implemented in GEOS-Chem
Ozone in the boundary layer during ICARTT 2004Observations 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).
(Mao et al., submitted to JGR)
Mean vertical profiles during ICARTT
O3 has no bias in boundary layer and free troposphere.HCHO provides good constraint on isoprene emissions.
ObservationsModel (GEOS-Chem)
(Mao et al., submitted to JGR)
Total organic nitrates excluding peroxyacylnitrates (∑ANs)
Model well reproduced ∑ANs.
∑ ANs is dominated by secondary organic nitrates(C3-C4).
∑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
Species Emission Chemical(P-L)
Dry Deposition
Wet Deposition
Net Export
NOx 386 -337 44 ------ 5PANs 24 13 ------ 11∑ANs ANs 18 7.4 3.6 7 R4N2 10 0.5 ------- 10HNO3 277 180 110 -3
Export of ∑ANs > Export of PANs
New chemistry
Previous studies without NOx recycling
Current anthro NOx emissions (2004)
Reduce current anthro NOx emissions by 50%
Isoprene↑NOx ↓OH ↓O3 ↓ due to O3+ISOP
Surface ozone response to isoprene emissions
NOx emissions↓
Sensitivity of ozone to isoprene emissions ↓
GFDL AM3 configuration for SENEX• Fully coupled chemistry-climate model
o Parameterizes aerosol activation into liquid cloud dropletso 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
Updated chemistry Standard AM3 Observations
CASTNET sites
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
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
HCHO yield at different NOx conditions
Computed in a photochemical box model. Initialized with 1ppb isoprene.O3 (40ppb), CO (100ppb), and NOx are held constant.
Prompt HCHO formation, important for deriving isoprene emission from satellite observations.
Yield of HCHO is lower at lower NOx concentrations, according to the model.
But the model could be wrong!
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)
(Lamsal et al., 2010)
Surface NOx emissions >> other emissions above the surface.
10% leak of surface NOx will double the effect of lightning.
Surface NOx ventilation will be critical for NOx/ozone in free trop
Observed ventilation from LIDAR (aerosol profiles Jul. 3, 2001, Barcelona, Campus Nord, UPC)!