wradlib Documentation - Bitbucket

wradlib Documentation, Release 0.1.1
Parameters r : array
array of ranges [m]
az : array
array of azimuth angles containing values between 0° and 360°. These are assumed to
start with 0° pointing north and counted positive clockwise!
sitecoords : a sequence of two floats
the lat / lon coordinates of the radar location
re : float
earth’s radius [m]
Returns lat, lon : tuple of arrays
two arrays containing the spherical latitude and longitude coordinates
Notes
Be aware that the coordinates returned by this function are valid for a sphere. When using them in GIS make
sure to distinguish that from the usually assumed WGS coordinate systems where the coordinates are based on
a more complex ellipsoid.
Examples
A few standard directions (North, South, North, East, South, West) with different distances (amounting to
roughly 1°) from a site located at 48°N 9°E
>>> r = np.array([0., 0., 111., 111., 111., 111.,])
>>> az = np.array([0., 180., 0., 90., 180., 270.,])
>>> csite = (48.0, 9.0)
>>> lat1, lon1= __pol2latlon(r, az, csite)
>>> for x, y in zip(lat1, lon1):
... print ’{0:6.2f}, {1:6.2f}’.format(x, y)
48.00, 9.00
48.00, 9.00
49.00, 9.00
47.99, 10.49
47.00, 9.00
47.99, 7.51
The coordinates of the east and west directions won’t come to lie on the latitude of the site because doesn’t
travel along the latitude circle but along a great circle.
3.5.2 wradlib.georef.polar2latlonalt
wradlib.georef.polar2latlonalt(r, az, elev, sitecoords, re=6370040.0)
Transforms polar coordinates to lat/lon/altitude coordinates.
Explicitely accounts for the beam’s elevation angle and for the altitude of the radar location.
This is an alternative implementation based on VisAD code (see http://www.ssec.wisc.edu/visaddocs/javadoc/visad/bom/Radar3DCoordinateSystem.html#toReference%28float[][]%29
and
http://www.ssec.wisc.edu/~billh/visad.html ).
42 Chapter 3. Library Reference