Land Surface Modelling Flashcards
What are land surface models?
Numerical models that solve the coupled fluxes of water, energy and carbon between the land surface and the atmosphere.
What are land surface models also known as?
Land carbon models
DGVM (dynamic global vegetation model)
Why are land surface models useful?
They help to understand and manage the earths natural resources.
What is the earth system model?
A set of models that can be run independently or together to simulate the Earth global climate.
What are the terrestrial feedbacks within the earth system?
- Snow cover and climate
- Soil moisture and evapotranspiration, precipitation
- Land use and cover change
- Carbon cycle
- Reactive nitrogen
- Biomass burning
How much of C is stored in land as a sink?
~30%
How many land models were used in the last Global Carbon Budget 2022?
16
What land surface models are used in the Global Carbon Budget?
- Vegetation
- Permafrost
- Soils
- Rivers and lakes
- Land use change
- Biosphere
How have land surface models changed over time?
They have become more complex.
70s - thought that land was a lower boundary to the atmosphere
Now - land is an integral part of the Earth system
What is the 3 main roles of land models within the Earth system model?
To show:
- Land atmosphere exchanges
- Land surface states (e.g. temp, C/N stocks)
- Land surface characteristics (e.g. albedo, roughness, vegetation type, LAI)
What do surface energy fluxes account for in the Earth system model?
What are the 3 ways land surface affects energy balance?
Solar energy input and output.
Input needs to balance output, extra will warm up sea.
- Albedo: trees are darker than grasses, so have lower albedo
- Surface roughness: trees are tall and aerodynamically rough
- Evapotranspiration: trees transpire more water than grasses, has a cooling effect
How does deforestation affect the climate at different latitudes?
Deforestation cools at high latitudes and warms at low latitudes.
What is the role of surface water balance in the Earth system model?
Water balances out
Rainfall = evapotranspiration, runoff, change in soil moisture over time.
What is the role of surface carbon balance in the Earth system model?
It takes into account GPP (photosynthesis), fire, respiration and land use change.
What are some land modelling challenges?
- Land surface heterogeneity
- Parameterisations. e.g. lab understanding of processes, trying to get data from as large sample as possible.
