Addressing m odel over- prediction of ozone influx from the Gulf of Mexico Jim Sm ith, Mark Estes and Jocelyn Mellberg Texas Com m ission on Environm ental Quality Ou Nopm ongcol and Greg Yarw ood Ram boll-Enviro n Presented at: CMAS 2 0 1 5 Air Quality Division
I ntroduction • Regional photochemical models are known to over-predict ozone concentrations transported onshore from the Gulf of Mexico. • Chlorine, iodine, and bromine along with numerous compounds containing them are known to participate in ozone formation and/ or destruction. • Halogen chemistry results in significant depletion of ozone in maritime environments. • Global models also over-predict marine ozone concentrations, adding to bias through derived boundary conditions. TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 2
Three Meteorological Regim es June 2 0 1 2 Continental/ Easterly Flow Reversal Flow Southerly Flow TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 3
Three Meteorological Regim es June 2 0 1 2 Continental/ Easterly Flow Reversal Flow Southerly Flow June 7-9, 2012 14:00 back June 10-15, 2012 14:00 back June 22-26, 2012 14:00 back trajectories, 50m agl at Galveston trajectories, 50m agl at Galveston trajectories, 50m agl at Galveston TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 4
Halogen Chem istry in CAMx • Augmented version of CB6r2: CB6r2 h • Iodine, Bromine and Chlorine pathways • Adds 88 reactions and 41 species to CB6r2 (in addition to current 216 reactions involving 75 species) • CAMx run time with CB6r2h ~ 1.6X longer than CB6r2 (when aerosols are not explicitly modeled) TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 5
Ozone Destruction Pathw ays Chlorine Cycles: ClO + HO 2 cycle ClO + ClO cycle ClNO 3 + H 2 O cycle Cl + O 3 → ClO + O 2 (Cl + O 3 → ClO + O 2 ) x 2 Cl + O 3 → ClO + O 2 ClO + HO 2 → HOCl + O 2 ClO + ClO → Cl 2 + O 2 ClO + NO 2 → ClNO 3 HOCl + hν → Cl + OH Cl 2 → 2 Cl ClNO 3 + H 2 O − aer → HOCl + HNO 3 HOCl + hν → Cl + OH Net: O 3 + HO 2 → OH + 2 O 2 2 O 3 → 3 O 2 O 3 + NO 2 + H 2 O → O 2 + HNO 3 + OH Bromine Cycles: BrO + HO 2 cycle BrNO 3 + H 2 O cycle HOBr + HBr cycle Br + O 3 → BrO + O 2 Br + O 3 → BrO + O 2 Br + O 3 → BrO + O 2 BrO + HO 2 → HOBr + O 2 BrO + NO 2 → BrNO 3 BrO + HO 2 → HOBr + O 2 HOBr + hν → Br + OH BrNO 3 + H 2 O − aer → HOBr + HNO 3 Br + R- H → HBr + R HOBr + hν → Br + OH HOBr + HBr − aer → Br 2 + H 2 O Br 2 → 2 Br Net: O 3 + HO 2 → OH + 2 O 2 O 3 + NO 2 + H 2 O → O 2 + HNO 3 + OH O 3 + HO 2 + R- H → 2 O 2 + H 2 O + R TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 6
Ozone Destruction Pathw ays ( cont.) Iodine Cycles: IO + HO2 cycle IO + IO cycle IO + NO2 cycle I + O3 → IO + O2 (I + O3 → IO + O2) x 2 I + O3 → IO + O2 IO + HO2 → HOI + O2 IO + IO → I + OIO IO + NO2 → IONO2 HOI + h ν → I + OH OIO + h ν → I + O2 IONO2 + hν → I + NO3 NO3 + h ν → NO + O2 NO + O3→ NO2 + O2 Net: O 3 + HO 2 → OH + 2 O 2 2 O 3 → 3 O 2 2 O3 → 3 O2 These cycles are referred to as catalytic cycles because the halogen atoms are regenerated in the reactions and therefore one I, Cl, or Br atom can potentially destroy many O 3 molecules. TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 7
Halogen Em issions • Molecular iodine (I 2 , CB6h species I2) emissions from seawater are assigned a constant flux of 4X10 8 molecules cm -2 sec -1 . • Chlorine and bromine-content of sea salt aerosols (SSCL and SSBR, respectively) are assumed to be produced by oceanic turbulence, bubble breaking, and viscous shear and are modeled using the CAMx sea-salt preprocessor. TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 8
Halogen Em issions • Halomethanes are generated by organic sources and allocated spatially according to monthly average chlorophyll-a observations from the SeaWIFS satellite. These include: – Iodomethane (CH 3 I, CH3I) – Diiodomethane (CH 2 I 2 , MI2) – Chloroiodomethane (CH 2 ICl, MIC) – Bromoiodomethane (CH 2 IBr, MIB) – Chlorobromomethane (CH 2 BrCl, MBC) – Dibromomethane (CH 2 Br 2 , MB2) – Dichlorobromomethane (CHBrCl 2 ,MBC2) – Chlorodibromomethane (CHBr 2 Cl, MB2C) – Bromoform (CHBr 3 , MB3) TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 9
Halogen Com pound Em issions: iodom ethane ( CH 3 I ) May 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 10
Halogen Com pound Em issions: iodom ethane ( CH 3 I ) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 11
Halogen Com pound Em issions: dibrom om ethane ( CH 2 Br 2 ) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 12
Halogen Com pound Em issions: chlorodibrom om ethane ( CHClBr 2 ) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 13
Halogen Com pound Em issions: brom oform ( CHBr 3 ) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 14
Halogen Com pound Em issions: chlorobrom om ethane ( CH 2 ClBr) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 15
Halogen Com pound Em issions: dichlorobrom om ethane ( CHCl 2 Br) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 16
Halogen Com pound Em issions: diiodom ethane ( CH 2 I 2 ) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 17
Halogen Com pound Em issions: brom oiodom ethane ( CH 2 I Br) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 18
Halogen Com pound Em issions: chloroiodom ethane ( CH 2 ClI ) June 2 0 1 2 , Each Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 19
Halogen Com pound Em issions: I odine ( I 2 ) Constant, Every Day TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 20
Halogen Com pound Em issions: Chloride from Sea Salt May 3 1 , 2 0 1 2 TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 23
Halogen Com pound Em issions: Chloride from Sea Salt June 1 6 , 2 0 1 2 TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 24
The TCEQ 2 0 1 2 Modeling Platform • Same Continental U.S. (CONUS) grid as EPA 2011 modeling platform, 36 km coarse grid • 2012 ozone season (May through September) • Nested 12-km South-Central US and 4-km East Texas grids • Updated emissions – MEGAN 2.10 biogenics with high-resolution LULC data (Guenther 2008 30-second data) – Link-based on-road emissions in Houston and Dallas-Fort Worth areas • CAMx with CB6 chemistry TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 25
The TCEQ 2 0 1 2 Modeling Platform • GEOS-Chem V9-01-03 boundary conditions • WRF 3.6.1 – 38 vertical layers – Pleim-Xiu land-surface model – YSU PBL scheme – WRFCAMx w/ 100 m K V patch • Not based on Texas’ hottest, driest year on record! TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 26
The TCEQ 2 0 1 2 Modeling Platform Texas Ozone Modeling Domains TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 27
Model Perform ance Com parison Galveston C1 0 3 4 Continental/ Easterly Flow Reversal Flow Southerly Flow TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 28
Model Perform ance Com parison Eastern Texas ( 4 km grid) Num ber Area DFW Monitors NETX Dallas-Fort Worth 17 (DFW) Houston-Galveston- 46 Brazoria (HGB) Beaumont-Port 8 Arthur (BPA) Northeast Texas CNTX 3 (NETX) BPA Central Texas 17 HGB (CNTX) Corpus Christi- CCV 10 Victoria (CCV) Other areas 7 Eastern Texas Total 109 (4 km grid) TCEQ Air Quality Division/ Ramboll Environ • Smith - Gulf of Mexico Ozone • CMAS - October 5, 2015 • Page 29
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