PHOTOCHEMICAL MODELING OF THE OZARKS ISOPRENE EXPERIMENT (OZIE): COMPARISON OF MEGAN AND BEIS Kirk Baker and Annmarie Carlton U.S. Environmental Protection Agency October 12, /24/2015 1

Biogenic VOCs 5/24/  Biogenic VOC comprise approximately 75-80% of the North American annual 2005 NEI  Biogenic emissions largely a function of plant type, leaf area index, temperature, and solar radiation (PAR)  Biogenic emissions for regional and global scale photochemical are typically developed from either MEGAN or BEIS  Model of Emissions of Gases and Aerosols from Nature (MEGAN), currently developed by NCAR  Biogenics Emission Inventory System (BEIS), currently developed by US EPA  July 1998 OZarks Isoprene Experiment (OZIE) field study designed for evaluation of biogenic models

MOTIVATION 5/24/  Compare MEGAN and BEIS emission estimates to surface and upper air measurements from OZIE field study  Evaluate sensitivity of CMAQ predictions when using alternative biogenic emissions models for  Primary gas phase species: e.g., isoprene, monoterpenes, sesquiterpenes  secondary species: e.g., O 3, PM 2.5, SOA  Primary and secondary: formaldehyde (HCHO)  Predictions of BVOCs are highly dependent on meteorology e.g., temperature, solar radiation  What is the bias in met model predictions of these variables?  How do predictions differ when alternative source of solar radiation are employed, e.g., how photosensitive are MEGAN and BEIS emission estimates?

Ozarks Isoprene Experiment: July /24/2015 4

OZIE Project Details 5/24/  Surface  TNMOC, isoprene, a-pinene, b-pinene, HCHO, O 3  Solar radiation, soil temperature, wind speed, wind direction, temperature, relative humidity  Aloft  Balloon: Isoprene, a-pinene, b-pinene  Aircraft (7 flights):, O 3, isoprene, TNMOC, HCHO Other Available Observation Data:  AIRS (1-hr avg)  Ozone, NO 2 /NO X, PM 10, CO  CASTNET/IMPROVE (24-hr avg)  Speciated PM 2.5  FSL RAOB Springfield, MO  Temperature, wind vector  U.S. Airways (DS472) (Hourly reported)  Temperature, mixing ratio, wind speed, wind direction

CMAQ Modeling Overview  Modeled June 15-July 31, 1998 episode  CMAQ v4.7.1 (N2a)  CB05 & AERO5  WRF v3.1  MCIP v  BEIS v3.14  MEGAN v2.04  2001 v2 based anthropogenic emissions  SMOKE inline emissions  36 km – continental US  12 km (blue)  34 and 14 vertical layers 5/24/2015 6

Biogenic Modeling 5/24/  BEIS v3.14 and MEGAN v2.04  WRF 2m Temp. and shortwave downward radiation (98a)  WRF 2m Temp. and satellite estimated photosynthetically activated radiation (PAR) (98b)  PAR is the visible light fraction of shortwave downward radiation  Satellite PAR estimates taken from GEWEX Continental Scale International Project (GCIP) and Americas Prediction Project (GAPP) Surface Radiation Budget (SRB) [  Satellite PAR resolution 0.5 ◦ x 0.5 ◦ and covers the continental U.S.  Missing hours and days replaced by hourly monthly average satellite estimated PAR

Monthly domain (12OZIE1) total emissions 5/24/ Moles/Day/ a98b98a 98b BEIS MEGAN 98a98b 98a: WRF PAR 98b: satellite PAR

Isoprene Emissions 5/24/ BEIS: Isoprene MEGAN: Isoprene Hour of the day (LST) Emissions (moles/sec)

Monoterpene Emissions 5/24/ BEIS: Monoterpenes MEGAN: Monoterpenes Hour of the day (LST) Emissions (moles/sec)

Sesquiterpene Emissions 5/24/ BEIS: Sesquiterpenes MEGAN: Sesquiterpenes Hour of the day (LST) Emissions (moles/sec)

Temperature & PAR at OZIE Sites 12  Warm bias over all hours & days  Morning and early afternoon PAR underestimated  Satellite PAR estimates compare better to ground observations Hour of the day (LST) Temperature Bias: OZIE sitesPAR Bias: OZIE sites Temperature (C) Watts/m 2

Isoprene Performance 12km grid, 34 vertical layers 13 Measured (ppbC) Modeled (ppbC)

Isoprene Bias: July Episode 5/24/ ppbC BEIS: Isoprene MEGAN: Isoprene

Monoterpene* Performance 15 α-pinene + β-pinene are approx % of total monoterpenes (Sakulyanontvittaya et al, 2008). There should be an overprediction. α-pinene + β-pinene Measured (ppbC) Modeled “TERP” (ppbC) α-pinene + β-pinene Measured (ppbC) Modeled “TERP” (ppbC)

Surface Formaldehyde Performance 5/24/ Measured (ppbC) Modeled (ppbC)

Balloon Measurements: Isoprene  Balloon: isoprene (right)  Model estimates (using satellite PAR) compared to vertical balloon and aircraft measurements  Measurements made in an open field 5/24/ Model Layer Concentration (ppbC)

Aircraft Measurements 5/24/ IsopreneFormaldehydeOzone Concentration (ppbC)Concentration (ppb) Model Layer measurements made over tree canopy

Model Performance: Ozone  MEGAN predicts slightly higher regional O 3  Satellite PAR MEGAN estimates result in slightly less O 3 than using WRF PAR 19 Bias (ppb) Observed Ozone Bin (ppb)

Model Performance: speciated PM2.5  Similar PM 2.5 performance using BEIS and MEGAN at rural speciated monitors  Sulfate performance related to SO 2 controls between 1998 and 2001  More OC using MEGAN emissions 20 98a98b98a98b BEIS MEGAN OBS Concentration (μg/m 3 )

Daily CMAQ PM2.5 SOC Estimates 21 *semi-emipirical EC tracer method to estimate SOC (Yu et al 2007) µg/m 3

Conclusions and Future Directions 22  MEGAN BVOC estimates are substantially higher and more photosensitive than BEIS  CMAQ O 3 and PM 2.5 estimates are similar with BEIS or MEGAN  Accept either for SIP modeling based on current state of chemical mechanisms  Future modeling study to investigate if control strategies would differ  Simulations with process analysis to investigate importance of VOCs, oVOCs  Test with different chemical mechanisms, e.g, low NO x isoprene chemistry  SOC predictions much higher with MEGAN but rural SOC still substantially underpredicted  Field Study to re-visit OZIE  Have BVOC emissions/ambient mixing ratios changed in response to changes in emissions and/or climate?  Measure SOA tracers to investigate which individual precursors/pathways contribute most to the SOC underprediction

Acknowledgements 5/24/  Allan Beidler, James Beidler, and Chris Allen (CSC) for BEIS, MEGAN, and SMOKE emissions modeling  Lara Reynolds (CSC) for WRF application  Rob Gilliam (US EPA/ORD) for assistance and troubleshooting for 4 km WRF application  Marc Houyoux and Rich Mason (US EPA/OAQPS) for assistance with anthropogenic emissions inventory  Christine Wiedenmyer (NCAR) for observation data  Mike Koerber (LADCO) for observation data  George Pouliot and Tom Pierce (US EPA/ORD)

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Future Field Study Directions 5/24/ What/where would a new “OZIE” experiment include?  Ozarks  Surface and aloft measurements  Isoprene, monoterpenes, and sesquiterpenes  SOC tracer measurements  OH radical  Speciated PM2.5; Ozarks get a lot of acidic aerosol in the summer from the Ohio Valley region  Carbon dioxide, NOX (is this a low NOX environment?)  Summer and non-summer periods like winter/fall/spring?  Roving measurements to different land use types like crops and grasslands? Urban biogenic assessment?

5/24/ MEGAN: Broadleaf Trees BELD3: Oak+Others BELD3: USGS Deciduous Trees *Others = Sycamore+Sweetgum+Willow+Populus Landuse Information MEGAN uses MODIS landuse and plant species information to make gridded emission factors BEIS uses BELD3, a combination of plant species information and USGS landuse Different isoprene emission factors for high emitting species (top right) and USGS deciduous tree category (bottom right) in BEIS Difficult to differentiate plant coverage and emissions with MEGAN’s gridded emission factor product (one plant functional type shown below)

Nitric Oxide Emissions  Biogenic nitric oxide (NO) estimated with BEIS3.12 comprises approximately 9% of the total continental United States 2005 annual NO emission inventory 5/24/ BEIS: Nitric Oxide MEGAN: Nitric Oxide

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