The Stable Boundary Layer exhibits a complex flow regime when the turbulent
motions are suppressed by thermal stratification. In this context, Turbulent Kinetic
Energy Dissipation Rate is an important term in the Turbulent Kinetic Energy
budget and knowing its behavior is important to understand this peculiar flow
regime. Furthermore, Turbulent Kinetic Energy budget has a relevant role in
numerical models so the proper representation of this term in terms of other Stable
Boundary Layer quantities is fundamental for numerical simulation and forecast. In
this work, some aspects of Turbulent Kinetic Energy Dissipation Rate have been
explored using Fluxes over Snow-covered Surfaces II data set. The vertical
profiles and Turbulent Kinetic Energy Dissipation Rate dependence with
different velocity and length scales and stability parameters have been analyzed.
Besides, the Turbulent Kinetic Energy Dissipation Rate role in the transition
between coupled and decoupled states has also been investigated. The turbulent
quantities were evaluated from 60-second time series sampled at 60Hz, starts at
2000 local standard time (1300 UTC) during 10 hours approximately, for 7
vertical levels (1, 2, 5, 10, 15, 20 and 30 m above surface). The Turbulent
Kinetic Energy Dissipation Rate has been determined from the same time
series using the longitudinal wind velocity second order structure function
(S_{u}^{2} = ⟨[u(r + Δr) - u(r)]^{2}⟩), where u is longitudinal wind velocity, r is the
spatial coordinate (spatial scale) over this direction and ⟨⟩ denotes the average
operator. In the subinertial range, the second order structure function is
described for a power-law gave by S_{u}^{2} = C_{k}ε^{2∕3}r^{2∕3}, proposed by Kolmogorov,
where C_{k} = 2.13 is Kolmogorov’s constant and ε is Turbulent Kinetic Energy
Dissipation Rate. For this study, Turbulent Kinetic Energy Dissipation Rate was
determined through second order structure function best fit for inertial subrange,
since the correlation coefficient is greater than 80% and power-law exponent
varies between 95%-105% of 2∕3 power-law. The time series that did not
ensure these parameters were refuse and correspond less than 5% of all data
set. In general, these time series had a very small vertical velocity variance.
All data obtained were sorted following values increasing longitudinal wind
velocity at 1 m level, and bin-averaged with a 1000 samples. To separate
coupled (weakly stable) and decoupled (very stable) regimes was applied a
crossover threshold in the longitudinal wind velocity at 1 m level equal to
2.11ms^{-1}. The general results shown that Bulk Richardson Number is a
most appropriated stability parameter to describe similarity relationships for
Turbulent Kinetic Energy Dissipation Rate, if using both local and for a
layer close to the ground values. Moreover, when the sensible heat flux is
introduced in the similarity relationship the data are better fitted than use only
a geometric height and friction velocity, as ordinary used in this kind of
approach. For this reason, length scale combined geometrical height and
Monin-Obukov length was adjusted to best fit the similarity relationship.