Kipp&Zonen LAS MkII Scintillometer - Manual (Page 78)

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Instruction Manual - LAS MkII Scintillometer
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CFL
LAS
MOST
PBL
RS
SL
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Constant Flux Layer
In general, in the lowest 10 % of the PBL the surface fluxes are constant with height and this part of the PBL is also
known as the Constant Flux Layer of the Surface Layer. Therefore fluxes measured in the SL can be considered as
being representative fluxes for the heat and mass exchange processes between the atmosphere and the surface.
Large Aperture Scintillometer
Monin-Obukhov Similarity Theory
A relationship describing the vertical behaviour of non-dimensionalised mean flow and turbulence properties within
the Surface Layer as a function of the Monin-Obukhov key parameters.
Planetary Boundary Layer
The PBL is the lowest region of the troposphere, which is directly affected by heating and cooling of the Earth’s
surface. In general the depth of the PBL varies between 100 to 2000 m. The depth of the PBL increases during the
day, when the surface is heated by the sun, and decreases during the night.
Roughness Sub-layer
Lowest part of the SL, in which the flow is influenced by individual roughness elements. Consequently, the SL can be
divided into the Constant Flux Layer and the Roughness Sub-layer. The height of the Roughness Sub-layer strongly
depends upon the height (size and form) of the roughness elements, but also upon the distribution. Usually, over tall
vegetation, 3 times the obstacle height is taken as the height of the Roughness Sub-layer.
Surface Layer
In general the SL begins at 3 times the vegetation height and has a typical depth of 20 m (at night) to 100 m (during
daytime conditions).