Applications - Surface Based Remote Sensing of the Atmospheric Boundary Layer - page 125

Fig. 4.32 Sensible heat flux profile ( lines connecting squares and circles) from windprofiler/RASS
measurements compared to model forecasts ( dashed line ) and in situ data ( dots and triangle ). From
Engelbart and Bange ( 2002 )

flux from the measured variances of the RASS sound propagation velocity (this still
includes effects of the vertical wind component), of temperature, and of the vertical
velocity component. Figure 4.32 shows an example.
Davis et al. ( 2009 ) determined the vertical turbulent heat flux from a vertically
pointing pulsed Doppler LIDAR using an estimation of the energy dissipation rate.
They started from (Davis et al. 2008 ):

∂
∂

1

2 w 3

,

w ≈ 0
g

+ 3 (4.23)

z

While the fluctuations of the vertical velocity components are taken directly from
the Doppler LIDAR soundings, the dissipation can be determined in two ways. The

so-called spatial spectral method estimates it from the slope of the spectrum of the
longitudinal velocity correlation. The so-called temporal spectra method estimates
it from the spectral energy at a given frequency and the mean horizontal wind speed.
Similarity laws for the atmospheric boundary layer may be used to determine
the near-surface turbulent fluxes of sensible ( H ) as well as latent heat ( LE )from
surface-layer turbulence measurements with scintillometers. For unstable condi-
tions, Kohsiek ( 1982 ) gives, using the structure functions for temperature, C T and
for moisture C q :