SMOKE biogenic emissions modeling can be accomplished with the Biogenic Emissions Inventory System, version 4 (BEIS4) approach using the processing scheme (Figure 2.11, “Biogenic-source processing steps and intermediate files”). The raw land use inventory data are imported and output as normalized emissions. Meteorology adjustments are then applied to the normalized emissions to create hourly model-ready emissions estimates.

The land use import can start with gridded BELD6 inputs along with summer and winter emission factors. In Section 2.16, “Biogenic processing”, we provide additional details about the SMOKE programs used for BEIS4 processing and its capabilities.

A variation can be run on the processing steps shown in Figure 2.11, “Biogenic-source processing steps and intermediate files” (see Figure 2.12, “Biogenic-source processing steps and intermediate files using both winter and summer emission factors”). In this variation, some grid cells use summer emission factors and some use winter emission factors. This is useful during the changes of seasons. Based on guidance from EPA, the summer emissions factors should be used for time periods after the last frost of the spring until the first frost of the fall, and winter emission factors should be used at other times of the year. To make such assignments by grid cell, the SMOKE utility Metscan analyzes the meteorology data for the entire year (or the period of interest) to establish which days each grid cell should use winter and summer emission factors. Metscan creates a winter/summer switch file that indicates the appropriate season for each grid cell for each day. More information on Metscan is available in Section 3.3.10, “Metscan”. The results of the meteorology analysis can then be used in the Figure 2.12, “Biogenic-source processing steps and intermediate files using both winter and summer emission factors” processing approach, in which both the summer and winter normalized emissions are provided to the meteorology adjustments step, along with the winter/summer switch file. The resulting model-ready emissions data have used the winter emission factors for all grid cells of the domain that have experienced the first freeze date of the year but not the last (within a calendar year, this is the time periods January through March and November through December in many regions), and the summer emission factors for all grid cells between the last and first freeze dates.

In Section 2.16, “Biogenic processing” we describe the SMOKE programs that are needed for each of these processing types for BEIS4 processing, and additional details about what activities are accomplished during each step.