cctreat/HPM-Arctic: HPM-Arctic

• Main Author: cctreat
• Format: Software
• Language: unknown
• Published: 2021
• Subjects: Arctic; Canada; permafrost
• Online Access: https://zenodo.org/record/4647666; https://doi.org/10.5281/zenodo.4647666

HPM-Arctic version integrates two earlier models: The Holocene Peat Model (HPM), a coupled carbon-hydrologic model for peatlands [Frolking et al., 2010], the Geophysical Institute Permafrost Lab soil thermal model GIPL2 [Marchenko et al., 2008]. Briefly, HPM simulates the development of a peat profile over millennia, from initiation, using an annual litter cohort approach so that results can be compared to dated peat cores. Rates of peat accumulation and decomposition are a function of plant community composition (litter quality), modified by dynamic environmental conditions, including water table level and water content in the unsaturated zone, and temperature profiles. Plant community composition (i.e., relative litter inputs from different plant functional types) is dynamic, responding to mean growing season water table depth and peat depth as a proxy for nutrient status. Annual net primary productivity (NPP) is set equal to annual litterfall, the carbon input for peat accumulation. NPP temperature sensitivity was modeled as a Q10 function, with a Q10 value of 1.8, based on an empirical relationship between mean annual air temperatures and above-ground net primary productivity for mosses, vascular plants, and trees that was developed for a transect of peatland sites in boreal Manitoba, Canada [Camill et al., 2001]. Peat bulk density in HPM is computed for each annual litter/peat cohort, and increases non-linearly from a minimum to a maximum value (50 – 130 kg m-3) as the cohort loses mass through decomposition (Frolking et al. 2010). The water table level is calculated from a simple water balance model (precipitation minus evapotranspiration plus net run-on/run-off, and the net peat water content determines the water table location, where the peat water content in the unsaturated zone is a function of peat bulk density and distance above the water table (Frolking et al. 2010) HPM-Arctic has been modified from the original version of HPM in several ways. Principally, it has been coupled to the Geophysical ...