On-line Monitoring of Weather Radar using Solar Interferences

The use of the radio frequency radiation of the sun for off-line calibration of the alignment of the antenna and the sensitivity of the receiver is a well established method and most radar manufacturers offer tools as part of their software packages. At the previous AMS radar conference, Darlington et al. (2003) showed that the pointing of weather radar antennas can be monitored using the sun without disturbing the operational scanning. Here we will present two methods for determining the antenna pointing and the receiver sensitivity using operational scan data.

Solar interferences can be detected automatically in polar reflectivity data produced operationally by a weather radar. Using a linear model the collected solar interferences can be analyzed quantitatively, and thus the biases of the elevation and azimuth reading of the radar antenna and the received solar power can be extracted. In the presentation the methods for monitoring of the weather radars will be introduced. In addition, the impact of atmospheric attenuation and refraction of solar radiation received at low elevations and the accuracy of correction methods will be discussed. Finally, the potential of the sun for quantitatively monitoring of operational weather radars will be demonstrated by examples from the Finnish and Dutch weather radar networks.