SMOKE currently supports the Biogenic Emissions Inventory System (BEIS) 4 and previous versions for processing emissions from biogenic origin. The overall processing performed by these models is quite different from the processing done for anthropogenic source categories. BEIS4 starts with spatial allocation of land use data as the first processing step (which is the same as importing the raw inventory data for anthropogenic sources). In the next step, the model computes compute normalized emissions for each grid cell and land use category. The final step is adjusting the normalized emissions based on gridded, hourly meteorology data and assigning the chemical species to output a model-ready biogenic emissions file. The following two subsections provide more detail about the most recent biogenic model implementation in SMOKE and give references to additional detail elsewhere.
The concepts in BEIS4 are similar to those in BEIS3 and previous versions, except the program Normbeis4 reads gridded land use data from a single file in I/O API input format (BELD6), and gridded Leaf Biomass inputs from a separate file BIOMASS. Normbeis4 creates normalized biogenic emissions for both winter and summer. The Tmpbeis4 program reads the MCIP meteorology data and makes these adjustments; these include the effects of temperature and solar radiation.
Tmpbeis4 gives the user two options for using the winter and summer normalized emissions. The recommended option is to use the gridded
soil temperature from the MCIP data to determine the fraction of summer and winter normalized emissions to use for each grid
cell. When gridded soil temperature is greater or equal to 290K, the summer normalized emissions will be used in the hourly
emissions calculations. If gridded soil temperature is below 282K, then the winter normalized emissions will be used in
calculations. Any grid cell with a soil temperature between 282K and 290K will use a certain fraction of winter and a fraction
of the summer normalized emissions in hourly emissions calculations. This recommended option should provide more realistic
emissions during season transition periods (e.g. winter to spring). The option for using winter and summer normalized emissions
is the same approach with Tmpbeis3 where Metscan is used. The winter emission factors are to be used during the "winter" period, which is defined as being after the first
date of freezing ground temperature and before the last date of freezing ground temperature. The SMOKE Metscan program can determine this time period and create a gridded file that indicates whether each grid cell is in a winter or
summer period for each day of the year. Using this file, which is optional, will cause Tmpbeis4 to read and use both the winter and summer normalized emissions files from Normbeis4. Whether the winter or summer normalized emissions are used for a given grid cell and hour is set by the output from the
Metscan program. Users can define the chemical species that are output from Tmpbeis4 using the speciation profile file, GSPRO. In this file, you can set an environment variable (BIOG_SPRO) that indicates which speciation profile code should be used for biogenic emissions. More information on Normbeis4 and Tmpbeis4 is provided in Section 4.13, “Normbeis4” and Section 4.19, “Tmpbeis4”.