CAMx Base 2011 version A MOVES2014 Sensitivity Simulation

Introduction

The Western Air Quality Study ran a CAMx sensitivity simulation derived from the 3SAQS Base 2011 version A CAMx configuration in which we replaced the onroad mobile emissions estimates from MOVES2010b with MOVES2014 emissions estimates. The CAMx 2011 MOVES emissions sensitivity simulation (CAMx_3SAQS_Base11a_MOVES) is a sensitivity to evaluate the change in model performance resulting from replacing the on-road mobile emissions estimates from the previous version of the MOVES (2010b) model with estimates from the current version of MOVES (2014). Other than the MOVES emissions data, the configurations of the Base11a and Base11a_MOVES simulations are exactly the same. Note that the Base11a simulation uses boundary conditions from the MOZART model.

EPA generated both MOVES simulations for the NEI2011 modeling platform. The on-road mobile emissions from the MOVES2010b simulation, which was used for the 3SAQS Base11a and Base11a2 CAMx simulations, was distributed by EPA as part of the NEI2011v1 platform. The MOVES2014 emissions are part of the NEI2011v2 platform and were released by EPA in early 2015.

The two MOVES simulations differ in the following ways:

• MOVES2014 is a reformulation of the MOVES model with different representations of the on-road mobile emissions processes, control programs, and user interface. See the EPA Q&A Fact Sheet on the differences between MOVES2014 and older versions of the model.
• Updated activity and speeds inventories
• Updated VOC speciation profiles

In March 2015 we used MOVES 2014 emissions factor look up tables created by EPA OAQPS for the NEI2011v2 modeling platform to prepare CAMx-ready emissions for the months of January and July. We used these emissions data to evaluate the sensitivity of CAMx to the changes resulting from the MOVES2014 on-road mobile emissions.

In the Results section of this page we are posting comparisons of the emissions and air quality modeling results for the base (2011a) and sensitivity simulations.

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Request for Comments

The Western States Air Quality Study modeling team is seeking comments from cooperators on the emissions and air quality results of this sensitivity simulation. In particular, we're interested in hearing from people with expertise in on-road mobile sources in the three-state region about the emissions changes between the two versions of MOVES.

We are seeking comments on the following questions about the MOVES emissions:

• Do the changes between the different versions of MOVES look reasonable?
• Are the winter/summer differences between the simulations reasonable?
• Are the magnitudes of the emissions reasonable?
• Are there other datasets/simulations available that we can use to validate the MOVES2014 results from EPA?

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Results

Emissions

We verified the MOVES activity comparisons presented here against the US EPA Notice of Data Availability for the NEI 2011v2 modeling platform. The EPA onroad mobile activity summaries are available here.

Table 1 shows annual county total activity comparisons between the EPA 2011v1 (MOVES2010b) and 2011v2 (MOVES2014) modeling platforms used for the two MOVES simulations. The Vehicle Miles Traveled (VMT) do not change in Colorado and Wyoming in the 2011v2 platform compared to 2011v1; several Utah counties exhibit decreases in VMT in the 2011v2 platform. The vehicle population (VPOP) does not change in Utah; counties in Colorado and Wyoming exhibit mixed VPOP changes.

Although the total VMT does not change in Colroado and Wyoming, the SCC6 plots show that the mix of vehicles changes in MOVES2010b relative to MOVES2014. Both states show a shift in VMT away from non-diesel passenger cars into non-diesel trucks and buses. Utah does not exhibit this same shift and instead shows a decrease across all fuel/vehicle classes in MOVES2014 relative to MOVES2010b.

The VPOP increase in Colorado is primarily attributed to an increase in the number of non-diesel trucks and buses. Although the state total VPOP does not change in Utah there is a slight shift in vehicles away from non-diesel passenger cars to non-diesel trucks and buses. They overall decrease in Wyoming VPOP is due to a decrease in all fuel/vehicle types.

Table 1. Comparison of Base11a (MOVES201b) and MOVES2014 County Total Annual Activity (VMT and Vehicle Population)

State	VMT	VPOP
Colorado	Plot	Plot
Utah	Plot	Plot
Wyoming	Plot	Plot

SCC6 VMT Comparisons between MOVES2010b and MOVES2014
SCC6 VPOP Comparisons between MOVES2010b and MOVES2014