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 on Peeters et al. (2009, PCCP) and Crounse et al. (2011, PCCP). How fast is the isomerization?

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! 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.

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 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)

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)

Total organic nitrates excluding peroxyacylnitrates (∑ANs) Model well reproduced ∑ANs. ∑ ANs is dominated by secondary organic nitrates (C3-C4). ∑ANs vs. HCHO∑ANs 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

NO y budget in eastern U.S. boundary layer for July 2004 SpeciesEmission Chemical (P-L) Dry Deposition Wet Deposition Net Export NO x PANs ∑ANs ANs R 4 N HNO Export of ∑ANs > Export of PANs

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 ↓

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

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 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!

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 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

Observed ventilation from LIDAR (aerosol profiles Jul. 3, 2001, Barcelona, Campus Nord, UPC)!