wradlib.qual.QualMethods

class wradlib.qual.QualMethods(obj)

Bases: XarrayMethods

wradlib xarray SubAccessor methods for Qual Methods.

pulse_volume(h, theta, **kwargs)

Calculates the sampling volume of the radar beam per bin depending on range and aperture.

We assume a cone frustum which has the volume \(V=(\pi/3) \cdot h \cdot (R^2 + R \cdot r + r^2)\). R and r are the radii of the two frustum surface circles. Assuming that the pulse width is small compared to the range, we get \(R=r= \tan ( 0.5 \cdot \theta \cdot \pi/180 ) \cdot range\) with theta being the aperture angle (beam width). Thus, the pulse volume simply becomes the volume of a cylinder with \(V=\pi \cdot h \cdot range^2 \cdot \tan( 0.5 \cdot \theta \cdot \pi/180)^2\)

Parameters:

obj (xarray.DataArray | xarray.Dataset)

Keyword Arguments:

• h (float) – pulse width (which corresponds to the range resolution [m])

• theta (float) – the aperture angle (beam width) of the radar beam [degree]

Returns:

obj (xarray.Dataset) – obj with volumes of radar bins at each range in ranges [\(m^3\)].

Examples

See Recipe #1: Clutter and attenuation correction plus composition for two DWD radars.

get_bb_ratio()

Returns the Bright Band ratio of each PR bin

With SR, we refer to precipitation radars based on space-born platforms such as TRMM or GPM.

This function basically applies the Bright Band (BB) information as provided by the corresponding SR datasets per beam, namely BB height and width, as well as quality flags of the SR beams. A BB ratio of <= 0 indicates that a bin is located below the melting layer (ML), >=1 above the ML, and in between 0 and 1 inside the ML.

Parameters:

obj (xarray.DataArray | xarray.Dataset)

Returns:

obj (xarray.Dataset) – obj with bb ratio and boolean array containing the indices of SR bins connected to the BB.

get_bb_ratio()	Returns the Bright Band ratio of each PR bin
pulse_volume(h, theta, **kwargs)	Calculates the sampling volume of the radar beam per bin depending on range and aperture.