Visualizing Winter Nitrate Formation Using CMAQ Process Analysis Charles Stanier – University of Iowa CENTER FOR GLOBAL AND REGIONAL ENVIRONMENTAL RESEARCH

Background Based on the work in –Yoo Jung Kim, S.N. Spak, G.R. Carmichael, N. Riemer, C.O. Stanier. Modeled aerosol nitrate formation pathways during wintertime in the Great Lakes region of North America. J. Geophys. Res., vol. 119, no. 21, pp –12445, doi /2014JD022320, Charles Stanier and Yoo Jung Kim have given a number of presentations on nitrate formation visualized through process analysis. These visualizations might be useful in atmospheric chemistry classes, so we are putting the powerpoints up there. Please use with the attribution: “Kim, Yoo Jung, et al. J. Geophys. Res. 2014; used with permission of Charles Stanier, Univ. or Iowa”. Questions – please contact Charles Stanier Sept 9, 2010IDNR Workgroup - Stanier 2

3 LADCO Winter Nitrate Study (Jan 1 – Mar 31, 2009)

Nitrate formation analysis by process analysis NO 2 + OH  HNO 3 (b) NO 2 + O 3  NO 3 + O 2 (a) NO 3 + NO 2 ↔ N 2 O 5 (c) NO 3 + VOC  organic products(g) N 2 O 5 + H 2 O(g)  2HNO 3 (d) N 2 O 5 + H 2 O(l)  2HNO 3 (e) RH and composition dependent accommodation coefficient, uncertain Daytime Nighttime

Model Configuration U of Iowa Community Multiscale Air Quality Model (CMAQ) v4.7.1 –CB05 gas phase / AERO5 aerosol module –ACM2 PBL closure –Mass-conserving advection –35 vertical layers LADCO’s 12 km regional modeling grid –Hourly boundary conditions from a 36 km simulation (with the same configuration) covering the continental United States. Meteorology –WRF with the RPO configuration selected by Iowa DNR, SESARM, and LADCO –ACM2 PBL closure –Pleim-Xu land surface module –RRTM radiation –Morrison microphysics –Kain-Fritsch cumulus –NARR 3-hourly met for initial and boundaries –Analysis nudging on NARR above the PBL, horizontal winds used for observational nudging in the PBL Emissions –LADCO’s 2007 emissions inventory used for 12km domain. –Day-specific biomass burning emissions from MODIS fire detection products. Process Analysis –Chemical and process rates stored for all layers up to 550 m, with focus on NOy processing and N2O5 heterogeneous chemistry

6 Mean total nitrate Jan – Mar CMAQ. µg / m 3

7 Reactio n ReactantsProducts R1NO 2 + hνNO + O R3O 3 + NONO 2 R4O + NO 2 NO R5O + NO 2 NO 3 R6O + NONO 2 R7NO 2 + O 3 NO 3 R14NO 3 NO 2 + O R15NO 3 NO R16NO 2 + NO2 NO 2 R17NO 3 + NO 2 NO + NO 2 R18NO 3 + NO 2 N2O5N2O5 R19N 2 O 5 + H 2 O2 HNO 3 R20N 2 O 5 + H 2 O + H 2 O2 HNO 3 R21N2O5N2O5 NO 3 + NO 2 R22NO + NO + O 2 2 NO 2 R23NO + NO 2 + H2OHONO R24NO + OHHONO R25HONONO + OH R26OH + HONONO 2 R27HONO + HONONO + NO 2 R28NO 2 + OHHNO 3 R29OH + HNO 3 NO 3 R30HO 2 + NOOH + NO 2 R31HO 2 + NO 2 PNA R32PNAHO 2 + NO 2 R33OH + PNANO 2 R46NO 3 + ONO 2 R47NO 3 + OHHO 2 + NO 2 R48NO 3 + HO 2 HNO 3 R49NO 3 + O 3 NO 2 R50NO 3 + NO 3 2 NO 2 R51PNA0.61HO NO OH NO 3 R52HNO 3 OH + NO 2 R53N2O5N2O5 NO 2 + NO 3 R89PANC 2 O 3 + NO 2 R90PANC 2 O 3 + NO 2 Integrated Reaction Rate Analysis

8 Daytime pathway (µmole/m 2 -day) Nighttime pathway (µmole/m 2 -day) Homogeneous nighttime pathway (µmole/m 2 -day) Heterogeneous nighttime pathway (µmole/m 2 -day) Through model layer 20 (~3.15 km)

9 DaytimeNighttime Total Nighttime Fraction

10 Aerosol Nitrate Fraction x10 Dotted = nighttime period. Solid = daytime. Mayville episode buildup periods N2O5 x 100 (ppb) Nitric Acid (ug/m3) Nitrate Aerosol (ug/m3) O 3 /10 Gas Ratio Total Ammonia NH3(g) OH+NO2 (day) N2O5 pathways (night)

11 Reservoir in µmole N / m 2. Fluxes are in µmole N / m 2 -hr. Black lines Aerosol process Horizontal advection and diffusion Vertical advection and diffusion Emissions DDEP a: net NO 3 radical formation c: net N 2 O 5 formation g: HNO 3 formation from the NO 3 radical Colored lines b: NO 2 + OH → HNO 3 d: homogenous formation of HNO 3 from N 2 O 5 Flux e: heterogeneous formation of HNO 3 from N 2 O 5 Milwaukee Day

12 Reservoir in µmole N / m 2. Fluxes are in µmole N / m 2 -hr. Black lines Aerosol process Horizontal advection and diffusion Vertical advection and diffusion Emissions DDEP a: net NO 3 radical formation c: net N 2 O 5 formation g: HNO 3 formation from the NO 3 radical Colored lines b: NO 2 + OH → HNO 3 d: homogenous formation of HNO 3 from N 2 O 5 Flux e: heterogeneous formation of HNO 3 from N 2 O 5 Milwaukee Night

13 Reservoir in µmole N / m 2. Fluxes are in µmole N / m 2 -hr. Black lines Aerosol process Horizontal advection and diffusion Vertical advection and diffusion Emissions DDEP a: net NO 3 radical formation c: net N 2 O 5 formation g: HNO 3 formation from the NO 3 radical Colored lines b: NO 2 + OH → HNO 3 d: homogenous formation of HNO 3 from N 2 O 5 Flux e: heterogeneous formation of HNO 3 from N 2 O 5 Mayville Day

14 Reservoir in µmole N / m 2. Fluxes are in µmole N / m 2 -hr. Black lines Aerosol process Horizontal advection and diffusion Vertical advection and diffusion Emissions DDEP a: net NO 3 radical formation c: net N 2 O 5 formation g: HNO 3 formation from the NO 3 radical Colored lines b: NO 2 + OH → HNO 3 d: homogenous formation of HNO 3 from N 2 O 5 Flux e: heterogeneous formation of HNO 3 from N 2 O 5 Mayville Night