[Review] Surface energy fluxes

Surface energy fluxes are the exchanges of energy, water and other atmospheric constituents on the surface, such as water molecule.

Surface energy fluxes mainly occur in the form of radiant energy, latent heat, sensible heat, and soil heat. The residue term of the heat fluxes is the heat that diffuses into the ground and be stored. The heat storage include physical energy storage, biochemical energy storage (2% of the incoming solar energy, which is amazingly small) , and the advected energy (which is important at the heterogeneous surface, such as oasis).

Some typical numbers (w/m2),

Downward shortwave radiation, 350

Longwave net radiation, Nighttime net radiation, -75

Terrestrial surfaces with different land cover types substantially alter the amount of the solar radiation. And the partitioning into latent and sensible heat changes from day to night.

(1) From albedo perspective:

dark color and rougher surface reflects less solar radiation, so therefore higher net radiation. Forest, wet soil have higher incoming energy.

(2) From partitioning in latent and sensible heat perspective: 

(a) For soil, wet soil is latent heat dominant, while dry soil is sensible heat dominant. 

(b) For forest, latent heat is slightly greater than sensible heat.

(c) For crop, latent heat is dominant. Why no sensible heat?

(3) From daytime and nighttime perspective: 

Wet soil have better thermal conductivity and store more heat at night.