240
WILLIAM B. LARGE
(non-dimensionalized) by z, u*, 0*, q* and L should be functions of the
non-dimensional group C = z/L. With all the scales common to all
surface layer flows, the structure of any layer and its turbulence, according to the theory, must always be "similar", with any dependencies on
5 universal. The most important consequences are the familiar logarithmic vertical profiles of mean wind (Tennekes, 1973), temperature and
humidity. Scaling the mean property gradients gives :
where I€ sets the non dimensional profiles for momentum, +,(<), and
for scalars, &(<) equal to 1 at neutral stability, < = 0. These functions
of the stability parameter, 5, have been determined empirically, and
acceptable fits to the data for present purposes are (Hogstrom, 1988) :
The uncertainty in these functions are a major problem with inferring
fluxes (u*, O* and q*) from measurements of mean property gradients.
Other serious issues with "the profile method" are the need for very
accurate instrumentation, the small signals (gradients) except near the
surface, and the danger of measuring below the surface layer.
Integration of these gradient relations (Paulson, 1970) gives the mean
property profiles in the surface layer, but not below,
The constants of integration, z0, ze and zq, are the roughness lengths,
that fully describe the surface as seen by the flow in the surface layer.
The integrated non-dimensional profiles for Y = (1 - 16 <)'I4 are:
3.1
Eddy covariance
Vertical transport through a PBL is accomplished by three dimensional turbulent eddies. At a fixed point their frequency is related to the
WILLIAM B. LARGE
(non-dimensionalized) by z, u*, 0*, q* and L should be functions of the
non-dimensional group C = z/L. With all the scales common to all
surface layer flows, the structure of any layer and its turbulence, according to the theory, must always be "similar", with any dependencies on
5 universal. The most important consequences are the familiar logarithmic vertical profiles of mean wind (Tennekes, 1973), temperature and
humidity. Scaling the mean property gradients gives :
where I€ sets the non dimensional profiles for momentum, +,(<), and
for scalars, &(<) equal to 1 at neutral stability, < = 0. These functions
of the stability parameter, 5, have been determined empirically, and
acceptable fits to the data for present purposes are (Hogstrom, 1988) :
The uncertainty in these functions are a major problem with inferring
fluxes (u*, O* and q*) from measurements of mean property gradients.
Other serious issues with "the profile method" are the need for very
accurate instrumentation, the small signals (gradients) except near the
surface, and the danger of measuring below the surface layer.
Integration of these gradient relations (Paulson, 1970) gives the mean
property profiles in the surface layer, but not below,
The constants of integration, z0, ze and zq, are the roughness lengths,
that fully describe the surface as seen by the flow in the surface layer.
The integrated non-dimensional profiles for Y = (1 - 16 <)'I4 are:
3.1
Eddy covariance
Vertical transport through a PBL is accomplished by three dimensional turbulent eddies. At a fixed point their frequency is related to the