Soil physics and hydrology modules

The soil physics module consists of four prognostic states, comprised of three soil layers and a snow layer. The soil layers (\(W_{ly1}\), \(W_{ly2}\), and \(W_{ly3}\)), are defined with depths z1, z2 and z3. We characterize the three layers as functionally distinct entities in which \(W_{ly1}\) represents near-surface moisture for bare soil evaporation and plant water uptake, and energy states to determine the temperature of heterotrophic respiration, \(W_{ly2}\) represent an additional plant water uptake reservoir, and \(W_{ly3}\) represents water and energy states innaccessible to plant water. Functionally, infiltration–including snowmelt–enter \(W_{ly1}\). Moisture and energy exchanges between \(W_{ly1}\), \(W_{ly2}\) and \(W_{ly3}\) are derived through thermal and hydraulic gradients. For each layer, we define the water balance differential equation as \(d(W_{n})/dt\), where \(W_n\) represents the moisture state of layer \(n\) (in mm H₂O), and the energy balance as \(d(E_{n})/dt\), where \(E_n\) represents the bulk energy content per unit area (in J m^-2).

Hydrology:

• Soil hydrology
  • Overview
  • Prognostic and diagnostic water states
  • Infiltration into surface
  • Inter-layer water transfers
  • Subsurface runoff
• Snow hydrology

Energy balance:

• LST-driven soil energy balance
  • 1. Closure of the soil energy inputs and outputs
  • 2. Water-mediated energy fluxes
  • 2. intra-soil energy exchanges mediated by thermal gradients and water fluxes
  • 3. LST-forced surface-to-suburface energy heat flux submodule
  • 4. diagnostic derivations of soil temperature and liquid H2O fraction, in coordination with the soil H2O balance module.