wradlib Documentation - Bitbucket

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wradlib Documentation, Release 0.1.1 At the moment, the national RADOLAN composite is a 900 x 900 grid with 1 km resolution and in polarstereographic projection. Parameters fname : path to the composite file Returns output : tuple of two items (data, attrs) • data : numpy array of shape (number of rows, number of columns) • attrs : dictionary of metadata information from the file header References [DWD2009] 3.2 Reading BUFR Files The Binary Universal Form for the Representation of meteorological data (BUFR) is a binary data format maintained by the World Meteorological Organization (WMO). The BUFR format was adopted by the OPERA program for the representation of weather radar data. This module provides a wrapper around the OPERA BUFR software, currently only for decoding BUFR files. In the future, functions for BUFR encoding might be added as well. If you intend to work with BUFR data, we recommend reading OPERA’s BUFR software documentation. decodebufr parse_desctable Main BUFR interface: Decodes BUFR file and returns metadata and values Parses the decriptor table and returns a dictionary of descriptors 3.2.1 wradlib.bufr.decodebufr wradlib.bufr.decodebufr(buffile) Main BUFR interface: Decodes BUFR file and returns metadata and values The BUFR file format is a self-describing binary format for meteorological data. wradlib uses the decoding software from the OPERA 3 program. All background information is available under http://www.knmi.nl/opera/bufr.html. Basically, a BUFR file consists of a set of descriptors which contain all the relevant metadata and a data section. The descriptors are identified as a tuple of three integers. The meaning of these tupels is described in the so called BUFR tables. There are generic BUFR tables provided by the WMO, but it is also possible to define so called local tables - which was done by the OPERA consortium for the purpose of radar data representation. This decoding function returns a two element tuple. The first element of the return tuple is the actual data array. It is a multi-dimensional numpy array of which the shape depends on the descriptor specifications (mostly it will be 2-dimensional). The second element is a tuple of two dictionaries (descnames, descvals). descnames relates the descriptor identifiers to comprehensible descriptor names. descvals relates the descriptor names to descriptor values. E.g. if the descriptor identifier was (0, 30, 21), the descriptor name would be ‘Number of pixels per row’ and the descriptor value could be an integer which actually specifies the number of rows of a grid. Parameters buffile : Path to a BUFR file Returns output: a tuple with two elements (data, metadata) : • data : the actual data as a multidimensional numpy array • metadata : tuple of two elements (descnames, descvals) 38 Chapter 3. Library Reference
wradlib Documentation, Release 0.1.1 – descnames: a dictionary of descriptor names – descvals: dictionary of descriptor values Examples >>> import wradlib.bufr as bufr >>> buffile = "wradlib/examples/data/test.buf" >>> data, metadata = bufr.decodebufr(buffile) >>> metadata >>> data.shape 3.2.2 wradlib.bufr.parse_desctable wradlib.bufr.parse_desctable(fpath) Parses the decriptor table and returns a dictionary of descriptors Parameters fpath : string representing the path to the descriptor table file Returns output : a tuple of two dictionaries (descnames, descvals) • descnames: a dictionary of descriptor names • descvals: dictionary of descriptor values 3.3 Data Transformation Module transforms data e.g. from RVP-units to dBZ-values to Z-values and vice versa. rvp2dBZ decibel idecibel r2depth Calculates dBZ-values from DWD RVP6 values as given in DX-product Calculates the decibel representation of the input values Calculates the inverse of input decibel values Computes rainfall depth (mm) from rainfall intensity (mm/h) 3.3.1 wradlib.trafo.rvp2dBZ wradlib.trafo.rvp2dBZ(x) Calculates dBZ-values from DWD RVP6 values as given in DX-product files. Parameters x : a number or an array 3.3.2 wradlib.trafo.decibel wradlib.trafo.decibel(x) Calculates the decibel representation of the input values dBZ = 10*log10(z) Parameters x : a number or an array (must not be
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