Recent Updates in v6.40 Chris Emery, Bonyoung Koo, Prakash Karamchandani, Gary Wilson, Greg Yarwood March 2, 2017

Outline Sponsored updates Miscellaneous updates Condensed halogen chemistry (TCEQ) Gas/PM chemistry and wet deposition updates (EPA) Parallel updates in OSAT/PSAT and DDM Land/ocean mask to support oceanic halogen emissions Miscellaneous updates ACM2 solver speed Landuse-dependent snow parameters Anthropogenic & biogenic SOA precursors in VBS

Updates in CAMx v6.4 Condensed Halogen Chemistry (TCEQ) Issue Oceanic halogen emissions are important for ozone depletion CB6r2h (v6.2) adds 88 reactions involving 40 I, Br, Cl species Approach CB6r2 + 16-reaction mechanism involving 9 Ix species (I-16b) Most important Ix reactions determined from DDM rate sensitivity analysis Add in-line Ix emissions = f(O3, SST, wind speed) Ix emission fluxes output to deposition file for diagnostics/reporting CB6r2h and I16-b result in similar ozone decrements (~5 ppb) over the Gulf of Mexico

Updates in CAMx v6.4 Condensed Halogen Chemistry (TCEQ) Schematic of the full iodine chemistry mechanism (I-30) in CB6r2h.

Updates in CAMx v6.4 Condensed Halogen Chemistry (TCEQ)

Updates in CAMx v6.4 Chemistry Updates (EPA) CB6r4 photochemistry Combine I-16b halogen mechanism + CB6r3 CB6r3 (v6.3): T/P dependent organic nitrate branching from alkanes Important for cold/high altitude photochemical applications Add pseudo-heterogeneous hydrolysis of isoprene-derived organic nitrate (INTR) INTR hydrolysis to HNO3 can be an important NOx loss pathway Add heterogeneous sulfate chemistry on fine crustal aerosols Negligible/minor sulfate impacts typically; larger impacts with high dust CB6 halogen chemistry (CB6r2h and I-16b) is disproportionately slow Inorganic Ix reactions are numerically “stiff” to solve Fast EBI solver for I species and improved EBI performance overall by ~20%

Updates in CAMx v6.4 Chemistry Updates (EPA) EPA 2011 Modeling Platform (July 28, 2015 NODA) CB6r4 1-hr O3 performance statistics (40 ppb cutoff) for July 2011   NMB (%) NME (%) R Region CB6r2 CB6r4 Change Northwest 2.3 1.6 -0.7 13.2 0.90 California -2.6 -3.7 -1.1 16.9 16.7 -0.2 0.75 0.77 +0.02 Rockies 1.0 0.6 -0.4 11.1 0.71 Southwest -8.5 -9.1 -0.6 16.0 16.3 +0.3 0.51 0.50 -0.01 Northern Plains 9.2 8.0 -1.2 15.6 15.2 0.73 0.72 Southern Plains 8.6 6.2 -2.4 18.7 17.8 -0.9 0.68 0.70 Midwest 10.5 -1.3 14.9 0.74 Southeast 21.3 18.9 23.7 21.8 -1.9 Northeast 8.9 7.4 -1.5 14.4 13.6 -0.8 0.85

Updates in CAMx v6.4 Chemistry Updates (EPA) 1-hr O3 at 4 rural sites along Gulf coastline, July 2011 CB6r2 CB6r4

Updates in CAMx v6.4 Chemistry Updates (EPA) 1-hr O3 at 4 rural sites along Atlantic coastline, July 2011 CB6r2 CB6r4

Updates in CAMx v6.4 Chemistry Updates (EPA) Land/ocean mask Necessary to ensure that in-line Ix emissions are emitted from ocean bodies only Removed from O3MAP file (optional field) Now explicitly defined in the landuse file LU = 1: “water” Historically all water coverage was assigned here Now used for ocean coverage LU = 3: “lake” Historically empty Now used for fresh water A "watermask" program allows for converting LU files if needed WRFCAMx may or may not be able to make this distinction Depends on LU database used in WRF

Updates in CAMx v6.4 Chemistry Updates (EPA) SOAP organic aerosol chemistry Remove 3 CG-SOA pairs and SOAH (17 species reduced to 10) 2 anthropogenic CG-SOA pairs by volatility (aromatics) 2 biogenic CG-SOA pairs by volatility (isoprene and terpenes) 2 non-volatile products (SOPA for anthropogenic and SOPB for biogenic) Add anthropogenic IVOC precursor (but not for biogenics due to greater uncertainties) Add aqueous SOA pathway from biogenic isoprene products (glyoxal) Literature update for SOA yields, saturation, water solubility You can still run CAMx with the original parameters Higher SOA with updated parameters – SOAP2 (over predictions) Lower SOA with original parameters – SOAP (under predictions)

Updates in CAMx v6.4 Chemistry Updates (EPA) Total SOA averaged over July 2011 SOAP (v6.3) SOAP2 – SOAP (v6.3) SOAP (v6.4) – SOAP (v6.3) SOAP2+newH – SOAP2

Updates in CAMx v6.4 Chemistry Updates (EPA) Total OC MPE over July 2011 SOAP (v6.3) SOAP2 SOAP2+newH SOAP (v6.3) SOAP (v6.4)

Updates in CAMx v6.4 Chemistry Updates (EPA) RADM-AQ aqueous PM chemistry Literature update for metal-catalyzed and peroxide sulfate oxidation Mostly minor impacts to sulfate concentrations SO2: v6.4 – v6.3 June 20, 2011 PSO4: v6.4 – v6.3 June 20, 2011

Updates in CAMx v6.4 Chemistry Updates (EPA) Probing Tools Tie in CB6r4 into OSAT and H/DDM OSAT accounts for an additional ozone destruction pathway by iodine and conversion of nitrogen tracer classes involving iodine nitrate (INO3) No change to tracer number, so OSAT runtimes are not be affected Tie in CB6r4, SOAP and RADM-AQ updates into PSAT (PM-DDM updates forthcoming) SOAP update reduces OA tracers, so PSAT will run faster for OA class

Updates in CAMx v6.4 Wet Deposition Update (EPA) Formulation/efficiency improvements (more removal, less “vertical transport” of semi-soluble species) June 20, 2011

Updates in CAMx v6.4 Wet Deposition Update (EPA) June 20, 2011

Updates in CAMx v6.4 Miscellaneous Updates ACM2 solver speedup as in CMAQ v5.1 CAMx/ACM2 runtimes are now similar to the default K-theory option. Extend ACM2 to work with H/DDM (has always worked with SA) Internal landuse-dependent snow parameters Changes for urban and shrub land to increase snow cover (and thus albedo) for a given snow depth Based on results reported by the Utah DAQ Simplified anthropogenic vs. biogenic VBS SOA classification Reflects the fact that aromatic precursors are mostly anthropogenic and isoprene and terpenes are mostly biogenic No impact to SOAP, no impact on VBS model results Use the updated PREPVBS tool to develop VBS emission inputs

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