Changes between Version 27 and Version 28 of doc/tec/lsm

Timestamp:

Apr 15, 2016 1:55:24 PM (9 years ago)

Author:

maronga

Comment:

--

doc/tec/lsm

@@ -345 +345 @@
 }}}
 
-== Usage ==
+=== 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 ==
+The lsm is activated by specifying a {{{&lsm_par}}} NAMELIST in the _p3d file, e.g.:
+{{{
+ &lsm_par veg_type = 2, soil_type = 3,
+          conserve_water_content = .T.,
+          c_surface = 0.0,
+          zs = 0.07, 0.28, 1.0, 2.89,
+          soil_moisture = 0.491, 0.491, 0.491, 0.491,
+          root_fraction = 0.49, 0.26, 0.25, 0.0,
+          soil_temperature = 279.5, 279.6, 279.1 279.1, 279.1, 
+/
+}}}
+In particular, PALM provides a set of predefined land surface types (parameter [wiki:doc/app/lsmpar#veg_type veg_type]) for which typical parameters are used to intialize the model. Moreover, a set of predefined soil types can be chosen (parameter [wiki:doc/app/lsmpar#soil_type soil_type]). You can overwrite the default parameters by explicitly prescribing them in the NAMELIST.
+
+A complete list of parameters and a detailed description can be found [wiki:doc/app/lsmpar here].
 
 == References ==