Download Biome-BGC 4.2
This project page serves as a central place for model information and source code. Biome-BGC is an ecosystem process model that estimates storage and flux of carbon, nitrogen and water. Biome-BGC is a computer program that estimates fluxes and storage of energy, water, carbon, and nitrogen for the vegetation and soil components of terrestrial ecosystems.
We call it a process model because its algorithms represent physical and biological processes that control fluxes of energy and mass. These processes include:
- New leaf growth and old leaf litterfall
- Sunlight interception by leaves, and penetration to the ground
- Precipitation routing to leaves and soil
- Snow accumulation and melting
- Drainage and runoff of soil water
- Evaporation of water from soil and wet leaves
- Transpiration of soil water through leaf stomata
- Photosynthetic fixation of carbon from CO2 in the air
- Uptake of nitrogen from the soil
- Distribution of carbon and nitrogen to growing plant parts
- Decomposition of fresh plant litter and old soil organic matter
- Plant mortality
- Fire
The model uses a daily time-step. This means that each flux is estimated for a one-day period. Between days, the program updates its memory of the mass stored in different components of the vegetation, litter, and soil.
Weather is the most important control on vegetation processes. Flux estimates in Biome-BGC depend strongly on daily weather conditions. Model behavior over time depends on the history of these weather conditions, the climate.
Biome-BGC: Required meteorological inputs
The primary driving variables for estimating ecosystem processes with Biome-BGC are daily meteorological data. One of the main premises of the Biome-BGC logic is that if we can adequately describe the dependence of key processes on environmental factors related to daily meteorology, then we can estimate these processes anywhere that daily meteorological data are available.
The following near-surface meteorological parameters are required by Biome-BGC:
- Daily maximum temperature (°C)
- Daily minimum temperature (°C)
- Daylight average temperature (°C)
- Daily total precipitation (cm)
- Daylight average partial pressure of water vapor (Pa)
- Daylight average shortwave radiant flux density (W/m2)
- Daylength (s)
In many cases, the only data available for a particular site are the daily maximum and minimum temperatures, and the daily total precipitation. We have developed simple and accurate algorithms to estimate the radiation and humidity parameters when they are missing (see our
MT-CLIM page).
In other cases, we are interested in performing simulations at a site that has no meteorological measurements at all. In this case, if there is a nearby weather station, perhaps at a different elevation, then
MT-CLIM is used to estimate the site meteorology. Often there is not a station very nearby, or there are two or more neighboring stations that might be used to estimate the daily meteorological parameters for the site. In that case it may be necessary to interpolate between individual stations, and possibley extrapolate to a different elevation. This is often the case when we perform gridded Biome-BGC simulations over large regions. We have developed a sophisticated set of algorithms to treat this problem (see our
Daymet page).
Conceptual Diagrams
