4.5 Data analysis and visualization

PALM is able to output data of different quantities as time series, vertical profiles (usually horizontally averaged), two-dimensional cross sections or 3d-volume data. Depending on the kind of output (time series, profiles, etc.) and the output format (ASCII  or binary) data are written to different files (file descriptions can be found in chapter 3.4). By default, all data output files are in NetCDF format (link to the NetCDF documentations in the Internet and on the PALM homepage), which can be processed by many public domain and commercial (graphic) software. Data from NetCDF files can also be easily read from FORTRAN programs provided that a NetCDF library is available. More detailed informations about the PALM-NetCDF-output is given in the next subchapter (4.5.1).

Due to historical reasons, PALM can also output data in other formats suitable for some special graphic software. The exact format of these files corresponds to the requirements of the respective software. Still available at IMUK are profil (time series, profiles), iso2d (2d cross sections) and AVS (e.g. iso-surfaces of 3d volume data). The special files created by PALM can be directly used as input files for these plot programs. Beyond that, profil and iso2d need additional information about the plot layout (e.g. titles, axes labels, arrangement of the coordinate systems, etc.) provided by so-called parameter files. These files are also created by the PALM, providing a default layout (e.g. plots produced by iso2d show. only isolines and no color shading). Within certain limits the plot layout can be steered by some PALM parameters. Beyond that the user can edit the parameter files created by PALM and change, supplement or remove the given default values according to his needs. Beside the file with the (binary) data to be visualized, AVS additionally needs a file with coordinate information (likewise binary) and an ASCII file in the so-called FLD format, which describes the structure of the two binary files. Coordinate and FLD file are also created by the PALM. However, with AVS (differently than with profile or iso2d) the plot layout must always be additionally designed by the user with the help of the AVS network editor.  

In the following subchapters, steering of the different data output and how to create plots of the data is described by some examples. Not all details of steering are mentioned. If necessary, these can be found within the description of the respective parameters.

 For most purposes it should be sufficient to read chapter 4.5.1 which explains the PALM-NetCDF-output.

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