Analytical Analysis of Energy Transfer within Canopies over Complex Terrain

Canopy layer acts as a buffer layer for momentum and energy transfer between atmosphere and ground. The ecosystem-atmosphere exchanges of materials, such as water, carbon dioxide, methane, nutrition, and pollutant, are directly or indirectly driven by the flows of momentum and energy through the canopy layer. We need basic knowledge of how momentum and energy transfer within canopies to understand the mechanisms of ecosystem-atmosphere exchanges. Without canopy, land-atmosphere interactions can be well incorporated into weather and climate models by a roughness-parameterization scheme formulated with K-theory and mixing-length theory. With canopy, if one still uses the roughness-parameterization scheme for the weather and climate models, the dynamic processes within canopy are ignored at all. A lot of efforts have been made to apply the K-theory and mixing-length theory into the canopy layer. However, observational evidence (e. g. Denmead and Bradley, 1985) indicate that these classic theories are invalidate within the canopy layer. Therefore, the transfer theory of momentum and energy through canopy layer is a persistent knowledge gap. Here, we review these theoretical issues and report some initial analytical results.

Key Words: energy transfer; K-theory; mixing-length theory; radiation cooling, vegetation, transfer coefficient, velocity-squared law, turbulent flux.

Acknowledgement: This research was supported by NSF Grants ATM-0930015, PSC-CUNY ENHC-42-64 & CUNY HPCC.