Changes between Version 17 and Version 18 of doc/app/examples/cbl

Timestamp:

Sep 16, 2010 12:55:05 PM (14 years ago)

Author:

suehring

Comment:

--

doc/app/examples/cbl

@@ -33 +33 @@
 The initialization parameters ([../../inipar &inipar]) are located at the beginning of the file. For analysis of a convective boundary layer of approx. 1000 m thickness the horizontal size of the model domain should amount to at least ''2 km x 2 km''. In order to resolve the convective structures a grid spacing of [../../inipar#dx dx]'' = ''[../../inipar#dy dy]'' = ''[../../inipar#dz dz]'' = 50 m'' is enough, since the typical diameter of convective plumes is more than ''100 m.'' Thereby the upper array index in the two horizontal directions needs to be [../../inipar#nx nx]'' = ''[../../inipar#ny ny]'' = 39'' . Since in each case the lower array index has the value ''0'', ''40'' grid points are used along both horizontal directions. In the vertical direction the domain must be high enough to include the entrainment processes at the top of the boundary layer as well as the propagation of gravity waves, which were stimulated by the convection. However, in the stably stratified region the grid resolution has not necessarily to be as high as within the boundary layer. This can be obtained by a vertical stretching of the grid starting from ''1200 m'' via [../../inipar#dz_stretch_level dz_stretch_level]''= 1200.0 m.'' \\\\
 
-Fast Fourier transformations ([../../inipar#fft_method fft_method]) are calculated using the Temperton-algorithm.\\
-The initial profiles for wind and temperature can be assigned via [../../inipar#initializing_actions initializing_actions]'' = 'set_constant_profiles'.'' The wind speed, constant with height, amounts to [../../inipar#ug_surface ug_surface]'' = ''[../../inipar#vg_surface vg_surface]'' = 0.0 m/s.'' In order to allow for a fast onset of convection, a neutral stratified layer up to ''z = 800 m'' capped by an inversion with ''dtheta/dz = 1K/100 m'' is given: [../../inipar#pt_vertical_gradient pt_vertical_gradient]'' = 0.0, 1.0,'' [../../inipar#pt_vertical_gradient_level pt_vertical_gradient_level]'' = 0.0, 800.0.'' The surface temperature, which by default amounts to ''300 K'', provides the fixed point for the temperature profile (see [../../inipar#pt_surface pt_surface]). Convection is driven by a given, near-surface sensible heat flux via [../../inipar#surface_heatflux surface_heatflux]'' = 0.1 K m/s''. A given surface sensible heta flux requires the bottom boundary condition for potential temperature to be [../../inipar#bc_pt_b bc_pt_b]'' = 'neumann'.'' Thus all initialization parameters are determined. These can not be changed during the run (also not for restart runs).
+Fast Fourier transformations ([../../inipar#fft_method fft_method]) are calculated using the Temperton-algorithm. The initial profiles for wind and temperature can be assigned via [../../inipar#initializing_actions initializing_actions]'' = 'set_constant_profiles'.'' The wind speed, constant with height, amounts to [../../inipar#ug_surface ug_surface]'' = ''[../../inipar#vg_surface vg_surface]'' = 0.0 m/s.'' In order to allow for a fast onset of convection, a neutral stratified layer up to ''z = 800 m'' capped by an inversion with ''dtheta/dz = 1K/100 m'' is given: [../../inipar#pt_vertical_gradient pt_vertical_gradient]'' = 0.0, 1.0,'' [../../inipar#pt_vertical_gradient_level pt_vertical_gradient_level]'' = 0.0, 800.0.'' The surface temperature, which by default amounts to ''300 K'', provides the fixed point for the temperature profile (see [../../inipar#pt_surface pt_surface]). Convection is driven by a given, near-surface sensible heat flux via [../../inipar#surface_heatflux surface_heatflux]'' = 0.1 K m/s''. A given surface sensible heta flux requires the bottom boundary condition for potential temperature to be [../../inipar#bc_pt_b bc_pt_b]'' = 'neumann'.'' Thus all initialization parameters are determined. These can not be changed during the run (also not for restart runs).
 
 Now the run parameters ([../../d3par &d3par] ) must be specified. To produce a quasi stationary boundary layer the simulated time should be at least one hour, i.e. [../../d3par#end_time end_time]'' = 3600 s.'' To stimulate convection, the initially homogeneous (zero) wind field must be disturbed ([../../d3par#create_disturbances create_disturbances]'' = .T.''). These perturbations should be repeated in a temporal interval of [../../d3par#dt_disturb dt_disturb]'' = 150.0 s'' until the energy of the perturbations exceeds the value [../../d3par#disturbance_energy_limit disturbance_energy_limit]'' = 0.01 m^2^/s^2^''. After each time step run time informations (e.g. size of the timestep, maximum velocities, etc.) are to be written to the local file [../../iofiles#RUN_CONTROL RUN_CONTROL] ([../../d3par#dt_run_control dt_run_control]'' = 0.0 s'').