Land Surface Processes in Global Climate Models (1) . Review of last lecture. Effects of different surface types: desert, city, grassland, forest, sea. Deeper heat/water reservoir, decreased Bowen ratio, thinner BL and enhanced convective instability.
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Land Surface Processes in Global Climate Models (1)
Sea Ice (CSIM)
The model is designed to run in three different configurations:
1. Stand-alone executable code as part of the Community Climate System Model (CCSM).
2. A subroutine call within the Community Atmosphere Model (CAM) in which CAM/CLM represent single executable code.
3. Stand-alone executable code in which the model is forced with atmospheric datasets. In this mode, the model runs on a spatial grid that can range from one point to global.
Dai, Qian, Trenberth and Milliman (2009), J. Climate
• Vegetation composition, structure, and phenology
• Absorption, reflection, and transmittance of solar radiation
• Absorption and emission of longwave radiation
• Momentum, sensible heat (ground and canopy), and latent heat
(ground evaporation, canopy evaporation, transpiration) fluxes
• Heat transfer in soil and snow including phase change
• Canopy hydrology (interception, throughfall, and drip)
• Snow hydrology (snow accumulation and melt, compaction, water transfer between snow layers)
• Soil hydrology (surface runoff, infiltration, sub-surface drainage, redistribution of water within the column)
• Stomatal physiology and photosynthesis
• Lake temperatures and fluxes
• Routing of runoff from rivers to ocean
• Volatile organic compounds
The land surface is represented by 5 primary sub-grid land cover types
The vegetated portion of a grid cell is further divided into patches of plant functional types,
each with its own leaf and stem area index and canopy height.
Each subgrid land cover type and PFT patch is a separate column for energy and water calculations.
Biogeophysical processes are simulated for
each subgrid landunit, column, and PFT independently and
each subgrid unit maintains its own prognostic variables.
The grid-average atmospheric forcing is used to force
all subgrid unit within a grid cell.
The surface variables and fluxes required by the atmosphere
are obtained by averaging the subgrid quantities
weighted by their fractional areas.