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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Marco Gabella
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DOI:10.17265/2328-2223/2015.04.001
A convenient and effective method for the absolute calibration of vertical and horizontal (dual-) polarization weather radar receivers is presented. The method is based on the relationship between the solar flux accurately measured in the S-band by the DRAO (Dominion Radio Astrophysical Observatory) and the retrieved power in the C-band by the vertical and horizontal receivers. One disadvantage of the method is that it requires the weather radar to be off-line for a few minutes during the tracking of the Sun (antenna radiation pattern beam axis hitting the center of the Sun). In order not to interfere with the operational scan, the method has been applied off-line to the 5th and last weather radar that will be integrated in the Swiss network at the beginning of 2016. Both during the Factory Acceptance Tests (FAT5) in summer 2015 and at the Weissfluhgipfel site in autumn 2015, the antenna-mounted Vertical (V) and Horizontal (H) polarization receivers were used to retrieve the maximum solar irradiance hitting the parabolic antenna. For both H and V polarizations, best results were obtained at the site, as a consequence of a better assessment of receiver path losses. The average retrieved value of the horizontal channel is closer than the vertical one to the DRAO reference: at the site, for instance, the average multiplicative error (Bias) between the H (V) channel and the reference is -0.05 (-0.26) dB; the standard deviation of the error is 0.13 (0.09) dB for the H (V) channel. These preliminary results are so encouraging and promising that MeteoSwiss is planning to repeat such off-line Sun tracking observations using not only this 5th and last weather radar but also the other 4 operational ones.
Weather radar receivers, monitoring, absolute radar calibration, effective system antenna with radome Gain, solar emission.