Boundary Layer Meteorology

Boundary Layer Meteorology

Han van Dop

Equation of State

pV =RT

First law of thermodynamics

Adiabatic gradient

Potential temperature

Entropy

Reference state

Bousssinesq approximations

Bousssinesq approximations

Continuity equation

Momentum equation

Temperature equation

THE REYNOLDS EQUATIONS

Closure

Surface layer

Surface type Roughness length (m) Smooth water/ice 10⁻⁴

Short grass 10⁻²

Low vegetation 0.05

Countryside 0.20

Low built-up area 0.6

Forests/cities 1 − 5

Mean Kinetic energy

Turbulent Kinetic Energy Equation

Energy Spectrum

Inertial Subrange

First Order Closure

1.5 Order closure

Large Eddy Simulation

ATMOSPHERIC BOUNDARY LAYERS

Phenomenology

Turbulent fluxes:

The Surface Layer

The Monin-Obukhov length scale

z/L < 0:

z/L > 0:

z/L < 0:

z/L > 0:

Dimension gradients vs. stability

variances

Spectra

The neutral boundary layer

with

or

solution

Resistance laws

=z/

h

Far from the surface (z~h)

Near the surface

Stability effects

RESISTANCE LAWS

THE CONVECTIVE BOUNDARY LAYER

DYNAMICS OF THE CONVECTIVE BOUNDARY LAYER

or

THE STABLE BOUNDARY LAYER

Low Level Jet

Low level jet

SURFACE ENERGY BALANCE

Incoming short wave radiation S

Outgoing short wave radiation S

Incoming long wave radiation L

Outgoing long wave radiation L

Net radiation RN

Profile method

Energy balance method

Evaporation

Virtual potential temperature

Shallow lake

Heterogeneous boundary

layers