Turbulent Transport in the Atmospheric Surface Layer - Transport in the Atmosphere-Vegetation-Soil Continuum - page 131

Turbulence

is governed can be characterized with is responsible for

Statistical description Vertical transport

of vertical wind speed and
transported quantity yields
can be measured with

consists among others of

(Gradients of) mean values Variances TKE Covariances

Eddy-covariance method

can - for atmospheric
applications-
not be linked through

is affected by is affected by

Navier-Stokes equations can be linked through Buoyancy

can be determined from Wind shear

Experimental data

is incorporated in is incorporated in

Similarity theory

needs definition of

are needed to determine form
as well as coefficients of

can be calculated from

Dimensionless groups

are related through

Similarity relationships

can be rewritten to obtain

Fluxes from observations at two levels

can be approximated by

Approximate analytical solutions

can be applied to

can be applied to

can be used to explain can be used to explain

Tw o levels in atmosphere One level in atmosphere,

one at surface
needs definition of

Feedback between stability and heat flux

Schmidt paradox

Roughness length for momentum and heat

Figure 3.22 Overview of Chapter 3 . Everything above 'Similarity theory' relates to
the physical reality. Everything below 'Similarity relationships' is a direct - mathe-
matical - consequence of the empirical relationships found by combining similarity
theory and experimental data.

heat, momentum and various gases in the atmospheric part of the soil-vegetation-
atmosphere continuum. Second, turbulence cannot be described from irst principles
and therefore we can relate various quantities (e.g., luxes and mean values) only
through empirical relationships.
Turbulence is a speciic state of a luid in which chaotic, though organized move-
ments occur. Because of the chaotic nature, the low can be described only in terms
of statistical quantities. One of those is the turbulent kinetic energy, which is inlu-
enced both by wind shear ('mechanical production of turbulence') and buoyancy. In