Changes between Version 6 and Version 7 of doc/app/netcdf


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Timestamp:
Sep 16, 2010 1:56:44 PM (15 years ago)
Author:
herbort
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  • doc/app/netcdf

    v6 v7  
    11== netCDF data output ==
    22
    3 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 [wiki:doc/app/iofiles here]). By default, all data output files are in netCDF format ([[http://www.unidata.ucar.edu/software/netcdf/]]), 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 [wiki:doc/app/ncgen here] and [wiki:doc/app/ncexample here].
     3PALM 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 [wiki:doc/app/iofiles here]). By default, all data output files are in netCDF format ([[http://www.unidata.ucar.edu/software/netcdf/]]), 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.
    44
    55Due 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 is '''AVS''' (e.g. iso-surfaces of 3d volume data). A description of the usage of the '''AVS''' software is given [wiki:doc/app/avs here].
     
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    11 The standard data output of PALM is netCDF (network Common Data Form) in 64-bit offset format. netCDF is an interface to a library of data access functions for storing and retrieving data in the form of arrays. netCDF is an abstraction that supports a view of data as a collection of self-describing, portable objects that can be accessed through a simple interface (protable means that netCDF data files can be read on any machine regardless of where they have been created). Array values may be accessed directly, without knowing details of how the data are stored. Auxiliary information about the data, such as what units are used, may be stored with the data. Generic utilities and application programs can access netCDF datasets (files) and transform, combine, analyze, or display specified fields of the data, e.g. the contents of a netCDF dataset can be viewed using the command '''ncdump''' (see further below). Many (public domain) graphic software has built in interfaces to read netCDF datasets (e.g. '''ferret''' or '''NCL'''). The complete netCDF documentation is available from the netCDF homepage ([[http://www.unidata.ucar.edu/software/netcdf/]]). The netCDF tutorial for FORTRAN90 can also be found on our web server.
     11The standard data output of PALM is netCDF (network Common Data Form) in 64-bit offset format. netCDF is an interface to a library of data access functions for storing and retrieving data in the form of arrays. netCDF is an abstraction that supports a view of data as a collection of self-describing, portable objects that can be accessed through a simple interface (protable means that netCDF data files can be read on any machine regardless of where they have been created). Array values may be accessed directly, without knowing details of how the data are stored. Auxiliary information about the data, such as what units are used, may be stored with the data. Generic utilities and application programs can access netCDF datasets (files) and transform, combine, analyze, or display specified fields of the data, e.g. the contents of a netCDF dataset can be viewed using the command '''ncdump''' (see further below). Many (public domain) graphic software has built in interfaces to read netCDF datasets (e.g. '''ferret''' or '''NCL''' ([wiki:doc/app/ncl see here])). The complete netCDF documentation is available from the netCDF homepage ([[http://www.unidata.ucar.edu/software/netcdf/]]). The netCDF tutorial for FORTRAN90 can also be found on our web server.
    1212
    1313The general output format of PALM data is determined by the runtime-parameter [wiki:doc/app/d3par#data_output_format data_output_format] (data_output_format = 'netcdf', by default). For historical reasons, some alternative formats can be selected. The accuracy of the netCDF output data can be set with parameter [wiki:doc/app/d3par#netcdf_precision netcdf_precision]. By default, data have single (4 byte) precision. Runtime-parameter [wiki:doc/app/d3par#data_output_format data_output_format] can be used to choose between the different netCDF file formats (classic, 64-bit offset, netCDF4/HDF5). The 64-bit offset format allows creating large files (file size only limited by the underlying file system), but each output variable (array) is still limited to 2GB. In netCDF4 format, there is no limit for the size of variables, and it also allows parallel I/O into one output file. However, some (graphic) software still does not support netCDF4 format.
     
    1515PALM allows the output of various data (e.g. cross sections, vertical profiles, timeseries, etc.) into different files. The following table gives an overview about the different kind of netCDF output data offered by PALM. Beside the local names of the files, the table also lists the minimum parameter settings which are necessary to switch on the output, as well as the parameters to be used to control the output.
    1616
     17||='''Kind of data'''  =||='''Local filename'''  =||='''Parameter settings \\ necessary to switch on output'''  =|| \
     18||='''Further parameters for \\ output control'''  =||
     19|----------------
     20{{{#!td style="vertical-align:top; text-align:left;width: 150px"
     21vertical profiles
     22}}}
     23{{{#!td style="vertical-align:top; text-align:left;style="width: 50px"
     24DATA_1D_PR_NETCDF
     25}}}
     26{{{#!td style="vertical-align:top; text-align:left;style="width: 75px"
     27data_output_pr, dt_data_output (or dt_dopr)
     28}}}
     29{{{#!td
     30averaging_interval, (or averaging_interval_pr), data_output_format, dt_averaging_input, dt_averaging_input_pr, skip_time_data_output (or skip_time_dopr), statistic_regions
     31}}}
     32|----------------
     33{{{#!td style="vertical-align:top"
     34timeseries
     35}}}
     36{{{#!td style="vertical-align:top"
     37DATA_1D_TS_NETCDF
     38}}}
     39{{{#!td style="vertical-align:top"
     40dt_dots
     41}}}
     42{{{#!td
     43data_output_format, statistic_regions
     44}}}
     45|----------------
     46{{{#!td style="vertical-align:top"
     47spectra
     48}}}
     49{{{#!td style="vertical-align:top"
     50DATA_1D_SP_NETCDF
     51}}}
     52{{{#!td style="vertical-align:top"
     53comp_spectra_level, data_output_sp, dt_data_output (or dt_dosp), spectra_directions
     54}}}
     55{{{#!td
     56averaging_interval (or averaging_interval_sp), data_output_format, dt_averaging_input_pr, skip_time_data_output (or skip_time_dosp)
     57}}}
     58|----------------
     59{{{#!td style="vertical-align:top"
     602d cross section (xy)
     61}}}
     62{{{#!td style="vertical-align:top"
     63DATA_2D_XY_NETCDF
     64}}}
     65{{{#!td style="vertical-align:top"
     66data_output (or data_output_user), dt_data_output (or dt_do2d_xy), section_xy
     67}}}
     68{{{#!td
     69data_output_format, data_output_2d_on_each_pe, do2d_at_begin, skip_time_data_output (or skip_time_do2d_xy)
     70}}}
     71|----------------
     72{{{#!td style="vertical-align:top"
    1773
     74}}}
     75{{{#!td style="vertical-align:top"
    1876
     77}}}
     78{{{#!td style="vertical-align:top"
     79
     80}}}
     81{{{#!td
     82
     83}}}
     84|----------------
     85{{{#!td style="vertical-align:top"
     86
     87}}}
     88{{{#!td style="vertical-align:top"
     89
     90}}}
     91{{{#!td style="vertical-align:top"
     92
     93}}}
     94{{{#!td
     95
     96}}}
     97|----------------
     98{{{#!td style="vertical-align:top"
     99
     100}}}
     101{{{#!td style="vertical-align:top"
     102
     103}}}
     104{{{#!td style="vertical-align:top"
     105
     106}}}
     107{{{#!td
     108
     109}}}
     110|----------------
     111{{{#!td style="vertical-align:top"
     112
     113}}}
     114{{{#!td style="vertical-align:top"
     115
     116}}}
     117{{{#!td style="vertical-align:top"
     118
     119}}}
     120{{{#!td
     121
     122}}}
     123|----------------
     124{{{#!td style="vertical-align:top"
     125
     126}}}
     127{{{#!td style="vertical-align:top"
     128
     129}}}
     130{{{#!td style="vertical-align:top"
     131
     132}}}
     133{{{#!td
     134
     135}}}
     136|----------------
     137{{{#!td style="vertical-align:top"
     138
     139}}}
     140{{{#!td style="vertical-align:top"
     141
     142}}}
     143{{{#!td style="vertical-align:top"
     144
     145}}}
     146{{{#!td
     147
     148}}}
     149|----------------
     150{{{#!td style="vertical-align:top"
     151
     152}}}
     153{{{#!td style="vertical-align:top"
     154
     155}}}
     156{{{#!td style="vertical-align:top"
     157
     158}}}
     159{{{#!td
     160
     161}}}
     162|----------------