Advancing Biogenic VOC Emissions Modeling for the Wasatch Front: Emission Factors, Speciation, and Stress-Induced Emissions

Project Goals

Improve Biogenic Volatile Organic Compound (BVOC) Emissions Modeling: The Wasatch Front experiences ozone nonattainment, and BVOCs (like isoprene and terpenes) significantly influence the region’s atmospheric chemistry. Accurate BVOC modeling is essential for developing effective air pollution control strategies.

Address Model of Emissions of Gases and Aerosols from Nature (MEGAN) Model Deficiencies: Previous modeling efforts for the Wasatch Front did not update BVOC emission factors or enhance landcover data for rural areas, particularly for shrubs and grasses.

Scope of Work

BVOC Emission Factor Database for Wasatch Front:

Synthesize a comprehensive, updated BVOC emission factor database for dominant urban and rural vegetation (trees, shrubs, grasses, crops) in the Wasatch Front by reviewing literature and incorporating recent data.
This will cover all 18 MEGAN BVOC classes and identify low BVOC-emitting urban vegetation.

Growth Form, Ecotype, and Species Composition Landcover Inputs for Rural Landscapes:

Update the MEGAN ecotype distribution for rural Utah using the 2022 LANDFIRE 30-m dataset and link it to species composition data from the USFS Forest Inventory and Analysis (FIA) and USDA Soil Data Mart databases.
Develop a more accurate 30-m resolution database for growth form cover fractions (trees, shrubs, grasses, crops) for rural landscapes, especially around the Wasatch Front, by calibrating NLCD and CDL data with high-resolution NAIP imagery and iTree surveys.

Update MEGAN Species Mappings to Chemical Mechanisms for Air Quality Modeling:

Review and update existing chemical mechanism mappings in MEGAN.
Incorporate support for a new chemical mechanism: CB7 with VCP.
Test and validate the new mappings with a one-day simulation of the Utah domain.

Estimate the Contribution of Stress-Induced Emissions to Total BVOC Emissions:

Use MEGAN3.2 stress algorithms to assess the impact of windstorms, air pollution (ozone), and temperature extremes on BVOC emissions, which are believed to underestimate monoterpenes and sesquiterpenes in current models.
Quantify the contribution of BVOCs from lawn mowing in the Wasatch Front.

Deliverables and Outcomes

Improved MEGAN emission model inputs for the Wasatch Front (updated emission factors, landcover files, and species mappings).
A more accurate BVOC emissions inventory for the region.
Quantification of stress-induced and lawn-mowing BVOC emissions.
All data, models, and documentation will be provided to UDAQ and integrated into the publicly available global MEGAN input files.