Changes between Version 28 and Version 29 of doc/tec/lsm

Timestamp:

Apr 15, 2016 1:56:12 PM (9 years ago)

Author:

maronga

Comment:

--

doc/tec/lsm

@@ -294 +294 @@
 
 For more details, see also [#viterbo Viterbo et al. (1995)] and [#balsamo Balsamo et al. (2009)].
+
+== Exception: water surfaces ==
+When prescribing grid points with water surface (i.e. {{{veg_class = 14,15}}}), the energy balance is solved as for land surface without evaporation from vegetation canopy and bare soil. Moreover, the water temperature is constant and time and is derived from the value of {{{pt_surface}}} at model start. In order to obtain realistic results, it is required to set a zero heat capacity for the ocean skin layer (e.g. {{{c_surface = 0.0}}}).
+
+A special feature of the treatment of water surfaces is the treatment of surface roughness chances due to water waves. The roughness lengths for momentum, heat, and moisture (''z'',,0,,, ''z'',,0,h,,, and ''z'',,0,q, respectively) are hence calculated after [#beljaars Beljaars (1994)] at each grid point as:
+{{{
+#!Latex
+\begin{align*}
+z_0 &= \dfrac{0.11 \nu}{u_\ast} + \alpha_\mathrm{Ch} \dfrac{u_\ast^2}{g}
+z_\mathrm{0,h} &= \dfrac{0.4 \mu}{u_\ast}
+z_\mathrm{0,h} &= \dfrac{0.62 \mu}{u_\ast}
+\end{align*}
+}}}
+Here, ''ν'' is the molecular viscosity, and ''α'',,Ch,, = 0.018 is the Charnock constant taken from the ECMWF-IFS model.
+
+Please note that this parameterization was developed for large-scale models where waves are a pure subgrid-scale phenomenon. When using large-eddy simulations, however, this might no longer be the case. It has not been studies whether this parameterization is appropriate in such cases and should only be used with caution.
+
+== Exception: pavement ==
+
+
+
 
 == Technical details ==
@@ -345 +366 @@
 }}}
 
-=== Exception: water surfaces ===
-When prescribing grid points with water surface (i.e. {{{veg_class = 14,15}}}), the energy balance is solved as for land surface without evaporation from vegetation canopy and bare soil. Moreover, the water temperature is constant and time and is derived from the value of {{{pt_surface}}} at model start. In order to obtain realistic results, it is required to set a zero heat capacity for the ocean skin layer (e.g. {{{c_surface = 0.0}}}).
-
-A special feature of the treatment of water surfaces is the treatment of surface roughness chances due to water waves. The roughness lengths for momentum, heat, and moisture (''z'',,0,,, ''z'',,0,h,,, and ''z'',,0,q, respectively) are hence calculated after [#beljaars Beljaars (1994)] at each grid point as:
-{{{
-#!Latex
-\begin{align*}
-z_0 &= \dfrac{0.11 \nu}{u_\ast} + \alpha_\mathrm{Ch} \dfrac{u_\ast^2}{g}
-z_\mathrm{0,h} &= \dfrac{0.4 \mu}{u_\ast}
-z_\mathrm{0,h} &= \dfrac{0.62 \mu}{u_\ast}
-\end{align*}
-}}}
-Here, ''ν'' is the molecular viscosity, and ''α'',,Ch,, = 0.018 is the Charnock constant taken from the ECMWF-IFS model.
-
-Please note that this parameterization was developed for large-scale models where waves are a pure subgrid-scale phenomenon. When using large-eddy simulations, however, this might no longer be the case. It has not been studies whether this parameterization is appropriate in such cases and should only be used with caution.
-
-=== Exception: pavement ===
-
-
 
 == Job preparation ==