Masked data output

From release 3.7a (r483) output of masked data is implemented in PALM. This feature allows to output quantities at different mask locations, e.g. 3d volume data or 2d cross sections of arbitrary extension within the model domain; 0d or 1d data at any positions and of any amount.
NetCDF4 file format is already available for masked data output.
Default quantities (instantaneous and time averaged) are declared with the parameter data_output_masks, user-defined quantities can be output with data_output_masks_user (see also User-defined output quantities).

Since r3436, terrain-following masked output is implemented. This allows to output masked quantities at a specified height above the surface.

Output steering

Different runtime parameters steer the output of the quantities assigned with data_output_masks and/or data_output_masks_user:

mask_x	all x-coordinates of mask locations (in multiples of mask scale)
mask_y	all y-coordinates of mask locations (in multiples of mask scale)
mask_z	all z-coordinates of mask locations (in multiples of mask scale)
mask_x_loop	loop begin, end and stride for x-coordinates of mask locations for masks (in multiples of mask scale)
mask_y_loop	loop begin, end and stride for y-coordinates of mask locations for masks (in multiples of mask scale)
mask_z_loop	loop begin, end and stride for z-coordinates of mask locations for masks (in multiples of mask scale)
mask_k_over_surface	vertical grid index above a surface to use for terrain-following masked output

These parameters define the masks. Each mask can be steered with a separate set of x-, y- and z-parameters. By default all gridpoints along the respective direction are used.

mask_scale_x	scaling length for masked data output in x-direction
mask_scale_y	scaling length for masked data output in y-direction
mask_scale_z	scaling length for masked data output in z-direction

The scaling lengths can be used to scale the parameters which defines the masks (mask_x, mask_y, mask_z, mask_x_loop, mask_y_loop or mask_z_loop). The scaling lengths apply for all masks.

dt_domask	temporal interval at which instantaneous masked data shall be output (in s)
skip_time_domask	no output of masked data before this interval has passed (in s)

The time intervals of the output times for each mask are determined with dt_domask. Individual time interval for output of temporally averaged data can be assigned using the parameter dt_data_output_av. The length of the averaging interval is controlled with averaging_interval. So far no particular parameters are existent for steering the time averaged output of each separate mask.


An umlimited amount of different masks can be defined. Each mask is output to one local file:

Instantaneous data of mask 1 are output to file DATA_MASK_01_NETCDF, time averaged data to file DATA_MASK_01_AV_NETCDF.
Instantaneous data of mask 2 are output to file DATA_MASK_02_NETCDF, time averaged data to file DATA_MASK_02_AV_NETCDF.
Instantaneous data of mask 3 are output to file DATA_MASK_03_NETCDF, time averaged data to file DATA_MASK_03_AV_NETCDF.
...

By default 50 different masks can be assigned. The amount of masks is steered with max_masks (=50 by default), which can only be changed in modules.f90. If more than 50 masks are desired, max_masks has to be changed to the corresponding value.

Examples

The following examples are given for the example_cbl run with a model domain size of 2000m x 2000m x 2000m and a resolution of 50.0m.

• 1. Output of one mask
• 2. Output of two different masks
• 3. Output of three different masks
• 4. Output of three different masks with scaling length
• 5. Output of four different masks with user-defined quantities
• 6. Output of terrain-following mask

1. Output of one mask

Mask 1: 3d volume data with an extension of 500m x 200m x 2000m from x = 0m to x = 500m, from y = 800m to y = 1000m and from the bottom to the top of the model domain. Output of instantaneous data of the three wind components.

&initialization_parameters

    nx = 39, ny = 39, nz = 40,
    dx = 50.0, dy = 50.0, dz = 50.0,
    .../

&runtime_parameters

    ...
    data_output_masks(1,:) = 'u','v','w',
   
    mask_x_loop(1,:) = 0., 500. ,50. ,
    mask_y_loop(1,:) = 800., 1000., 50. ,/

If mask_x, mask_y, mask_z or mask_x_loop, mask_y_loop, mask_z_loop are not assigned, all gridpoints are used along the corresponding direction.
Output is done at t = dt_data_output since dt_domask is not assigned.

2. Output of two different masks

Mask 1: xy cross section from x = 500m to x = 1000m and from y = 1000m to 2000m at heights 0m, 50m, 100m, 500m, 1000m and 1200m. Output of instantaneous and time averaged data of the three wind components.
Mask 2: Every second gridpoint in all directions. Output of instantaneous data of the potential temperature.

&initialization_parameters

    nx = 39, ny = 39, nz = 40,
    dx = 50.0, dy = 50.0, dz = 50.0,
    .../

&runtime_parameters

    ...
    data_output_masks(1,:) = 'u','v','w','u_av','v_av','w_av',
    data_output_masks(2,:) = 'theta',
   
    mask_x_loop(1,:) = 500.,1000.,50. ,
    mask_y_loop(1,:) = 1000.,2000.,50. ,
    mask_z(1,:) = 0.,50.,100.,500.,1000.,1200.,

    mask_x_loop(2,:) = 0.,2000.,100.,
    mask_y_loop(2,:) = 0.,2000.,100.,
    mask_z_loop(2,:) = 0.,2000.,100.,

    dt_domask = 600.,1800.,
    skip_time_domask = 3600.,3600.,/

Output starts after 1h simulation time (see skip_time_domask) for both masks and is done every 10 minutes for mask 1 and every 30 minutes for mask 2 (see dt_domask).

3. Output of three different masks

Mask 1: 1d data along x-direction at y = 50m, 200m, 500m and 1000m and every fifth grid point in z-dircetion. Output of instantaneous data of the w-velocity component.
Mask 2: Output of the potential temperature at position x = 0m, y = 500m, z = 200m, 300m and 400m.
Mask 3: xz cross section at y = 400m, 450m, 600m. Output of time averaged data of the three wind components.

&initialization_parameters

    nx = 39, ny = 39, nz = 40,
    dx = 50.0, dy = 50.0, dz = 50.0,
    .../

&runtime_parameters

    ...
    data_output_masks(1,:) = 'w',
    data_output_masks(2,:) = 'theta',
    data_output_masks(3,:) = 'u_av','v_av','w_av',
  
    mask_y(1,:) = 50., 200., 500., 1000.,
    mask_z_loop(1,:) = 0.,2000.,250.,

    mask_x(2,:) = 0.,
    mask_y(2,:) = 500.,
    mask_z_loop(2,:) = 200.,400.,100.,

    mask_y(3,:) = 400., 450., 600.,

    dt_domask = 1800.,
    skip_time_domask = 0.,3600.,3600.,/

Output starts from the beginning for mask 1 and after 1h simulation time (see skip_time_domask) for mask 2 and 3. It is done every 30 minutes for mask 1 and at time intervals of dt_data_output for mask 2 and 3 (see dt_domask).

4. Output of three different masks with scaling length

Mask 1, 2 and 3 as in example 3

&initialization_parameters

    nx = 39, ny = 39, nz = 40,
    dx = 50.0, dy = 50.0, dz = 50.0,
    .../

&runtime_parameters

    ...
    data_output_masks(1,:) = 'w',
    data_output_masks(2,:) = 'theta',
    data_output_masks(3,:) = 'u_av','v_av','w_av',

    mask_scale_x = 10.0,
    mask_scale_y = 10.0,
  
    mask_y(1,:) = 5., 20., 50., 100.,
    mask_z_loop(1,:) = 0.,2000.,250.,

    mask_x(2,:) = 0.,
    mask_y(2,:) = 50.,
    mask_z_loop(2,:) = 200.,400.,100.,

    mask_y(3,:) = 40., 45., 60.,

    dt_domask = 1800.,
    skip_time_domask = 0.,3600.,3600.,/

Output starts from the beginning for mask 1 and after 1h simulation time (see skip_time_domask) for mask 2 and 3. It is done every 30 minutes for mask 1 and at time intervals of dt_data_output for mask 2 and 3 (see dt_domask).

Since mask_scale_x and mask_scale_y are assigned, the parameters for steering the mask locations along x- and y-direction (here mask_x and mask_y) has to be given in multiples of mask_scale_x and mask_scale_y.

5. Output of four different masks with user-defined quantities

Mask 1: 1d data along x-direction at y = 50m, 200m, 500m and 1000m and every fifth grid point in z-dircetion. Output of instantaneous data of the w-velocity component.
Mask 2: Output of the potential temperature at position x = 0m, y = 500m, z = 200m, 300m and 400m.
Mask 3: xz cross section at y = 400m, 450m, 600m. Output of time averaged data of the three wind components and the user-defined quantity u2.
Mask 4: xy cross section at z = 100m, 250m, 500m. Output of the user-defined quantity u2.

&initialization_parameters

    nx = 39, ny = 39, nz = 40,
    dx = 50.0, dy = 50.0, dz = 50.0,
    .../

&runtime_parameters

    ...
    data_output_masks(1,:) = 'w',
    data_output_masks(2,:) = 'theta',
    data_output_masks(3,:) = 'u_av','v_av','w_av',
  
    mask_y(1,:) = 50., 200., 500., 1000.,
    mask_z_loop(1,:) = 0.,2000.,250.,

    mask_x(2,:) = 0.,
    mask_y(2,:) = 500.,
    mask_z_loop(2,:) = 200.,400.,100.,

    mask_y(3,:) = 400., 450., 600.,

    mask_z(4,:) = 100., 250., 500.,

    dt_domask = 1800.,
    skip_time_domask = 0.,3600.,3600.,/

&user_parameters

    data_output_masks_user(3,:) = 'u2',
    data_output_masks_user(4,:) = 'u2',

Output starts from the beginning for mask 1 and after 1h simulation time (see skip_time_domask) for mask 2, 3 and 4. It is done every 30 minutes for mask 1 and at time intervals of dt_data_output for mask 2, 3 and 4 (see dt_domask).

6. Output of terrain-following mask

Mask 1: xy cross section from x = 500m to x = 1000m and from y = 1000m to 2000m at the second, fith and tenth grid point above the surface. Output of instantaneous and time averaged data of the three wind components.

&initialization_parameters

    nx = 39, ny = 39, nz = 40,
    dx = 50.0, dy = 50.0, dz = 50.0,
    .../

&runtime_parameters

    ...
    data_output_masks(1,:) = 'u','v','w','u_av','v_av','w_av',
   
    mask_x_loop(1,:) = 500.,1000.,50. ,
    mask_y_loop(1,:) = 1000.,2000.,50. ,
    mask_k_over_surface(1,:) = 2, 5, 10,

    dt_domask = 600.,
    skip_time_domask = 3600.,/

Output starts after 1h simulation time (see skip_time_domask) for both masks and is done every 10 minutes for mask 1 and every 30 minutes for mask 2 (see dt_domask).