wradlib Documentation - Bitbucket

wradlib Documentation, Release 0.1.1
Parameters r : a float or an array of floats
Corresponds to rainfall intensity in mm/h
a, b : Parameters of the Z/R relationship
Standard values according to Marshall-Palmer are a=200., b=1.6 The German Weather
Service uses a=256 and b=1.42 instead of the Marshall-Palmer defaults.
Returns output : a float or an array of floats
reflectivity in mm**6/m**3
3.4.3 wradlib.zr.z2rEnhanced
wradlib.zr.z2rEnhanced(z)
Calculates rainrates from radar reflectivities using the enhanced three-part Z-R-relationship used by the DWD
(as of 2009)
To be used with polar representations so that one dimension is cyclical. i.e. z should be of shape (nazimuths,
nbins) –> the first dimension is the cyclical one. For DWD DX-Data z’s shape is (360,128).
Parameters z : a float or an array of floats
Corresponds to reflectivity Z in mm**6/m**3 must be a 2-D array
Returns r, si : r - array of shape z.shape - calculated rain rates
si - array of shape z.shape - calculated shower index for control purposes. May be
omitted in later versions
3.5 Georeferencing
polar2latlon
polar2latlonalt
polar2centroids
polar2polyvert
centroid2polyvert
project
create_projstr
projected_bincoords_from_radarspecs
Transforms polar coordinates (of a PPI) to latitude/longitude coordinates.
Transforms polar coordinates to lat/lon/altitude coordinates.
Computes the lat/lon centroids of the radar bins from the polar coordinates.
Generate 2-D polygon vertices directly from polar coordinates.
Calculates the 2-D Polygon vertices necessary to form a rectangular polygon ar
Convert from latitude,longitude (based on WGS84) to coordinates in map proje
Conveniently supports the construction of proj.4 projection strings
Convenience function to compute projected bin coordinates directly from
3.5.1 wradlib.georef.polar2latlon
wradlib.georef.polar2latlon(r, az, sitecoords, re=6370040)
Transforms polar coordinates (of a PPI) to latitude/longitude coordinates.
This function assumes that the transformation from the polar radar coordinate system to the earth’s spherical
coordinate system may be done in the same way as astronomical observations are transformed from the horizon’s
coordinate system to the equatorial coordinate system.
The conversion formulas used were taken from http://de.wikipedia.org/wiki/Nautisches_Dreieck [accessed
2001-11-02] and are only valid as long as the radar’s elevation angle is small, as one main assumption of
this method is, that the ‘zenith-star’-side of the nautic triangle can be described by the radar range divided by
the earths radius. For lager elevation angles, this side would have to be reduced.
3.5. Georeferencing 41