Changes between Version 49 and Version 50 of doc/tec/bc

Timestamp:

Nov 19, 2018 11:05:57 AM (6 years ago)

Author:

suehring

Comment:

--

doc/tec/bc

@@ -309 +309 @@
 '''Method 2:''' In many cases detailed information about the Reynolds stress and turbulent length scales are not available, so that these information need to be parametrized. If no ASCII input file is provided in the input folder, this will be done automatically and the turbulence statistics at the inflow boundary will be estimated. 
 Please note, the derived turbulence statistics will depend on the height above ground but not on the horizontal location. Parametrization of the Reynolds stress follows [#rotach1996 Rotach et al. (1996)].
-The diagonal components ''u,,11,,'', ''u,,22,,'', indicating the horizontal velocity variances, are estimated as follows:
-{{{
-#!Latex
-\begin{equation*}
-u_{i,i} = u_{*} ( 0.35\,(-\frac{z_i}{\kappa\,L})^\frac{2}{3}) + (5 - 4\,\frac{z}{z_i}, \: (i \in (1,2) )\,,
-\end{equation*}
-}}}
-with ''u'',,*,, being the friction velocity, ''k'' the von-Karman constant, ''L'' the Obukhov length, and ''z,,i,,'' the mean boundary-layer depth. 
-''u'',,*,, is estimated from the mean horizontal wind speed at the boundary at the first vertical grid point.
+The diagonal components ''R,,11,,'', ''R,,22,,'', indicating the horizontal velocity variances, are estimated as follows:
+{{{
+#!Latex
+\begin{equation*}
+R_{i,i} = u_{*} ( 0.35\,(-\frac{z_i}{\kappa\,L})^\frac{2}{3}) + (5 - 4\,\frac{z}{z_i}, \: (i \in (1,2) )\,,
+\end{equation*}
+}}}
+with ''u'',,*,, being the friction velocity, ''k'' the von-Kármán constant, ''L'' the Obukhov length, and ''z,,i,,'' the mean boundary-layer depth. Please note, ''u'',,*,,, ''L'' and ''z,,i,,'' are area-averaged values in this case.
+''z'' describes the height of the respective model grid level. 
+''u'',,*,, is estimated from the mean horizontal wind speed at the first vertical grid point from the data provided at the lateral boundary using MOST. For the sake of simplicity, neutral conditions are assumed with Φ,,m,, = 1. 
+''L'' is computed from the area-averaged surface temperature, sensible heat flux profile and roughness length in the model domain. 
+''z,,i,,'' is estimated from the bulk Richardson criterion, with ''z,,i,,'' being the height where the bulk Richardson first exceeds the critical Richardson number of 0.25, according to [=#heinze2017 Heinze et al. (2017)]. 
+In case of stable stratification (''L'' > 0) or neutral stratification (''L'' = 0), the first term is omitted for the computation of ''R,,ii,,''.  
+
+
+
+method 2 undergoes testing
 
 At this point we emphasize that this method only generates turbulence which is statistically correlated. Large coherent structures such as e.g.  hexagonal pattern as typically observed in a convective boundary layer, however, cannot be generated by this method. So far, turbulence is only added to the three wind components. No perturbations are added to the subgrid-scale turbulent-kinetic energy and potential temperature.
@@ -586 +594 @@
 * [=#rotach1996] '''Rotach M, Gryning SE, Tassone C.''' 1996. A two-dimensional Lagrangian stochastic dispersion model for daytime condtions. Q.J.R. Meteorol. Soc. 122: 367–389.
 
+* [=#heinze2017] '''Heinze R, Moseley C, Böske L, Muppa S, Maurer V, Raasch S.''' 2017. Evaluation of large-eddy simulations forced with mesoscale model output for a multi-week period during a measurement campaign. Atmos. Chem. Phys. 17: 7083-7109
+
 * [=#briscolini1989] '''Briscolini M, and Santangelo P.''' 1989. Development of the mask method for incompressible unsteady flows. J. Comput. Phys. 84: 57–75.