SMOKE handles SCCs differently for on-road mobile sources compared with all other source categories. SMOKE programs assume that on-road mobile SCCs have the following form:

MOVES can model six different fuel types: Gasoline, Diesel, Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), Ethanol, and Electricity. Table 2.2, “MOVES Fuel Type” indicates a list of original MOVES fule types. Table 2.3, “Aggregated fuel types and corresponding MOVES fuel types” shows how the four aggregated SCC fuel types are mapped to the six MOVES fuel types.

The vehicle types used in SMOKE’s on-road mobile source processing are described in Table 2.4, “MOVES Vehicle type codes and descriptions”. Table 2.5, “Aggregated vehicle types and corresponding MOVES vehicle types” shows how the eight aggregated MOVES vehicle types are mapped to the original MOVES vehicle types.

MOVES can produce emission factors for possible combinations between 13 MOVES vehicle types and fuel types. For the efficiency of SMOKE processing, the emission factors can be aggregated to a list of vehicle types listed in Table 2.5, “Aggregated vehicle types and corresponding MOVES vehicle types”.

MOVES can model nine different road types: rural restricted/unrestricted access with ramps, rural restricted/unrestricted access without ramps, urban restricted/unrestricted access with ramps, urban restricted/unrestricted access without ramps, and off-network (Table 2.6, “Road class and corresponding MOVES road type”). Table 2.7, “Aggregated road types and corresponding MOVES road types” indicates how the 6 aggregated MOVES road classes are mapped to the nine MOVES road types.

MOVES can model 14 different process types: including on-roadway and off-network emissions processes, for the selected pollutants. Off-network emission processes (e.g., parked engine-off, engine starts, and idling, and fuel vapor venting in MOVES (Table 2.8, “Process types and corresponding MOVES road type”). Table 2.9, “Aggregated process types and corresponding MOVES process types” indicates how the 14 aggregated MOVES process types are mapped to the 14 MOVES process types.

The approach for running MOVES for SMOKE relies on the concept of reference counties. These are counties that are used during the creation and use of emission rates to represent a set of similar counties (i.e., inventory counties) called a county group. The purpose of the reference county approach is to reduce the computational burden of running MOVES on every county in your modeling domain. By using a represenative county, the user generates key emission rates for the single county in MOVES and then utilizes these factors to estimate emissions for all counties in the county group through SMOKE. The reference county is modeled at a range of speeds and temperatures to produce emission rate lookup tables (grams/mile or grams/vehicle/hour, depending on mobile emission process). The variables that are assumed to be constant across the county group members (and the reference county) are fuel parameters, fleet age distribution and inspection/maintenance (I/M) programs. The variables that can vary within the county group are vehicle miles traveled (VMT), source type vehicle population, roadway speed, and grid cell temperatures. Determining the reference counties and their respective county groups is a key aspect of utilizing the SMOKE-MOVES tool. It is ideal for the user to create each county group based on the similarity between the county characteristics (e.g., urban and rural) and the meteorological conditions (e.g., temperature and relative humidity). The user should avoid grouping counties that have significantly different meteorological conditions.

Along with the concept of reference county approach, the concept of a fuel month is very important. It is used to indicate when a particular set of fuel properties should be used in a MOVES simulation. Similar to the reference county, the fuel month reduces the computational time of MOVES by using a single month to represent a set of months. To determine the fuel month and which months it corresponds to, the user should review the State-provided fuel supply data in the MOVES database for each reference county. If the fuel supply data change throughout the year, then group the months by fuel parameters. For example, if the grams/mile exhaust emission rates in January are identical to February's rates for a given reference county, then use a single fuel month to represent January and February. In other words, only one of the months needs to be modeled through MOVES.

The meteorological data processor program Met4moves prepares spatially and temporally averaged temperatures and relative humidity data to set up the meteorological input conditions for MOVES and SMOKE using the Meteorology-Chemistry Interface Processor (MCIP) output files.

Met4moves must be run after MCIP and before the MOVES Driver script “Runspec_generator.pl” and SMOKE modeling system.

The following are the major processing steps that Met4moves performs:

When the MOVES model runs for SMOKE, it runs for all emissions processes (or modes), including on-roadway and off-network emissions processes, for the selected pollutants. Off-network emission processes (e.g., parked engine-off, engine starts, and idling, and fuel vapor venting) in MOVES are hour-dependent due to vehicle activity assumptions built into the MOVES model; the emission rate depends on both hour of the day and temperature. On-roadway emission processes (e.g., running exhaust, crankcase running exhaust, brake wear, tire wear, and on-road evaporative), on the other hand, do not depend on hour. In MOVES, these emission processes are categorized into three major groups:

MOVES emission rates are organized into four lookup tables (RPD, RPV, RPP, RPH), depending on emission process and whether the vehicle is parked or in motion. The approach to running MOVES for SMOKE is unique for each emission rate table listed in Table 2.10, “MOVES Emission Processes by Emission Rate Tables”. A complete inventory must use the emission rates from all three tables. Note that refueling emission process is not a subject to MOVES emission rate table approach yet.

The RPD lookup table is used to provide estimates of on-roadway emissions processes from mobile sources, using a separate file for each reference county. The on-road running processes that appear in this table include running exhaust, crankcase running exhaust, brake wear, tire wear, on-road evaporative permeation, on-road evaporative fuel leaks, and on-road evaporative vapor venting. The units of the emission rates in this table are grams/mile. The lookup fields for the factors are temperature and average speed. There are 16 set speed bins defined in Table 2.11, “MOVES Default Speed Bins” (i.e., avgSpeedBinID 1=2.5mph, 2=5mph, 3=10mph, …16=75mph). The avgBinSpeed is used for interpolation in the RPD table.

The RPV lookup table is used to provide estimates of off-network emission processes (parked engine-off, engine starts, and idling), except for the evaporative off-network vapor venting emissions process. A separate file is provided for each reference county. The off-network emission processes include start exhaust, crankcase start exhaust, off-network evaporative permeation, off-network evaporative fuel leaks, extended idle exhaust, and crankcase extended idle exhaust. Fuel month, temperature, and local hour are the lookup fields in this table, and hours are in the local time of the modeling county. The units of the emission rates are grams/vehicle/hour. Note: Although the units are grams/vehicle/hour, the number of vehicles (i.e., population) should not be temporally allocated to hours in SMOKE. Instead, a county total of vehicle population should be multiplied by emission rates at any given hour. The number of starts per vehicle by hour is already accounted for in the MOVES lookup table.

The RPP table is used only to estimate emissions for off-network fuel vapor venting when the vehicle is parked. This process type includes diurnal (when the vehicle is parked during the day) and hot soak (immediately after a trip when the vehicle parks) emissions types. The process depends on the rate of rise in temperature and the maximum temperature achieved during the day for the diurnal emissions type, and on the hourly temperatures for the hot soak emission type. The lookup fields for this table are reference fuel month and hour of day. As with the RPV table, the units of the emission rates are grams/vehicle/hour. The estimated emissions rates need to be multiplied by the county vehicle population. The reference county lookup tables contain 24-hour emission rates per hour per vehicle using a reference county temperature profile with different minimum and maximum temperatures. The average day county emissions are determined by interpolating between the minimum and maximum temperatures for the modeling county generated by Met4moves. Section 2.8.4.8, “Meteorological Data Processing” summarizes how Met4moves processes meteorological data for both MOVES and SMOKE.

The RPH table is used only to estimate emissions for on-roadway extended idle exhaust process from mobile sources, using a separate file for each reference county.

The following Table 2.12, “MOVES Pollutant Groups” provides a list of available MOVES pollutant groups that the user can specify to model within MOVES. The choice of pollutant groups(s) determines what pollutants are included in the three emission rate lookup tables (RPD, RPV, and RPP) output by MOVES. The letter 'X' marks the key pollutants for inclusion, and a letter 'd' signifies that the pollutant is included as a default in the MOVES run because a key pollutant depends on it. The user modifies the control.in input file to specify the pollutant group.