1. The Surface Energy Balance and Turbulent Fluxes
Why The SEB?
What and How?
SEB components (Rn, SH, LE, G, B, Tskin, ε, α, examples)
ABL (neutral, stable, unstable, Ri, z/L, entrainment, LCL, eddy covariance, bulk formulations, examples)
SEB measurements
SEB remote sensing
SEB modeling (LSMs)
International Programs (GEWEX)
Bonan, Ch. 13, Ch. 14; Kiehl and Trenberth (1997)

2. The Atmospheric Boundary Layer
ABL = The part of the troposphere that is directly influenced by the presence of the earth’s surface, and responds to surface forcings with a time scale of about an hour or less. See

3. The Atmospheric Boundary Layer
Definition: ABL = The part of the troposphere that is directly influenced by the presence of the earth’s surface, and responds to surface forcings with a time scale of about an hour or less.
Structure: free atmosphere, entrainment zone, mixed layer (where U, θ, q almost constant with height), surface layer (where vertical fluxes of momentum, heat, and moisture are almost constant with height)
Thickness: typically 1 km; varying from 20 m to several km; deeper with strong solar heating, strong winds, rough surface, or upward mean vertical motion in the free troposphere.
Both structure and thickness have a strong diurnal cycle.
Turbulent motions (opposite to laminar flow)
chaotic swirls; rapid chaotic fluctuations in winds, temperature, moisture, other mass
generated mechanically (in the presence of strong near surface mean winds), or
generated thermally (strong solar heating  high buoyancy  vertical motion)
(mostly daytime, land; also common over the oceans)
ABL clouds: fog, fair weather cumulus, stratocumulus
               ,

4. Potential Temperature
The potential temperature (θ) of a parcel of air at pressure P is the temperature that the parcel would acquire if adiabatically brought to a standard reference pressure P0 (= 1000 millibars).
where T = the current absolute temperature (in K) of the parcel, R = the gas constant of air, and cp = the specific heat capacity at a constant pressure. See GPC Appendix C for derivations.
θ is a more dynamically important quantity than T. Under almost all circumstances, θ increases upwards in the atmosphere, unlike T which may increase or decrease. θ is conserved for all dry adiabatic processes, and as such is an important quantity in the ABL (which is often very close to being dry adiabatic). The dry adiabatic lapse rate: Γd = g/cp = 9.8 °C/km
θ is a useful measure of the static stability of the unsaturated atmosphere.
stable, vertical motion is suppressed;
unstable, convection is likely

5. Stüve diagram (Thermodynamic Diagram)
Isotherms are straight and vertical, isobars are straight and horizontal and dry adiabats are also straight and have a 45 degree inclination to the left while moist adiabats are curved (see also GPC Appendix C, Fig. C.1).
T=20°C,
P=1000 mb
 θ= 20°C
P=900 mb
θ= 28.96°C
A parcel with P, T, q  Td =? q*=?, RH=?, LCL=? Δq=?

6. Thermodynamics

7. Air Flow and Turbulent Vortices
Air flow can be imagined as a horizontal flow of numerous rotating eddies, a turbulent vortices of various sizes, with each eddy having 3D components, including vertical components as well. The situation looks chaotic, but vertical movement of the components can be measured from the tower.

8. Determine Vertical Fluxes

9. Reynolds Decomposition and Eddy Covariance

10. Reynolds Decomposition and Eddy Covariance

11. Bulk Aerodynamic Formulas (Parameterizations)
τ = ρ CDM Ur2
SH = cp ρ CDH Ur [Ts – Ta(zr)]
LE = L ρ CDE Ur [qs – qa(zr)]
CDN = [κ / ln(zr/z0)]2
CDM = CDN,M fM(RiB)
CDH = CDN,H fH(RiB)
CDE = CDN,E fE(RiB) or Eqn (14.31) in Bonan (2008)

12. Global Distribution of Sensible Heat Flux

13. Global Distribution of Latent Heat Flux

14. Regional Patterns of The Surface Energy Balance
West Palm Beach, Fl energy balance (ly/day) West Palm Beach, Florida  is located in a warm and moist climate. Latent energy transfer into the air is greatest during the summer time which is the wettest period of the year, and when net radiation is the highest. During the summer, sensible heat transfer decreases as net radiation is allocated to evaporation and latent heat transfer.
Yuma, AZ energy balance (ly/day)
At the other extreme is Yuma, Arizona, a warm and dry climate. The most noticeable characteristic of this place is the lack of latent heat transfer. Though  ample radiation is available here, there is no water to evaporate. Nearly all net radiation is used for sensible heat transfer which explains the hot dry conditions at Yuma.

15. Modeling of The Surface Energy Balance
NCAR CLM: for global climate modeling and projections
NCEP Noah LSM: for numerical weather predictions

16. 2008 CCSM Distinguished Achievement Award
NCAR CLM 3.5
Biogeochemistry
Ecosystem Dynamics
Hydrology
Biogeophysics
2008 CCSM Distinguished Achievement Award
Niu & Yang, 2003, 2006
Yang et al., 1997, 1999
Niu, Yang, et al., 2005
Niu, Yang, et al., 2007
Yang & Niu, 2003
Collaborators: UT (Z.-L. Yang, G.-Y. Niu, R.E. Dickinson); NCAR (G.B. Bonan, K. Oleson, D. Lawrence)

17. Noah LSM with hydrological enhancements
Collaborators: UT (Z.-L. Yang, G.-Y. Niu, D. Maidment), NCAR (Fei Chen, Dave Gochis); NCEP (Mike Ek, Ken Mitchell)
Explicit diffusive wave overland flow
Groundwater discharge,
reservoir routing &
Explicit channel routing
Subgrid Disaggregation
Dynamical Routing Methodologies
The Noah land surface model has been significantly enhanced to enable physically-based, spatially-distributed treatment of surface hydrological processes such as hillslope runoff, shallow groundwater flow and streamflow.
Explicit saturated
subsurface flow
fully distributed flow/head
reservoir levels
distributed soil moisture
distributed land/atmo fluxes
distributed snow depth/SWE
1-D ‘Noah’ Community
Land Surface Model

18. Observing The Surface Energy Balance
FLUXNET
See also other flux measurement networks (e.g., Ameriflux, CarboEurope, Fluxnet Canada, and iLEAPS).

19. International Programs
GEWEX