Improvement of X-band radar rainfall estimates using a microwave link

In recent years the significance of highly resolved rainfall information in space and time for hydrological applications increased steadily. Weather radar systems provide this information but the derivation of quantitatively reliable radar rainfall estimates is still known to be problematic. The attenuation of the radar signal by rainfall has been identified as crucial and especially X-band radars are affected by this phenomenon. The current methods of correcting for attenuation face many problems, mainly because the actual amount of attenuation is unknown. s paper attenuation and rainfall information derived from a microwave link are used as a reference to correct an X-band radar for rainfall. A microwave link receiver is co-located with an X-band weather radar in Essen, Germany. Therefore, the microwave link provides path integrated attenuation and rainfall information parallel to a radar beam over a distance of 30 km. The correction of radar rainfall is done in two steps: first, the radar data are corrected for attenuation and in a second step the microwave link derived rainfall is used together with information obtained from distrometer data to calculate the rainfall from the corrected radar reflectivities. A network of twelve rain gauges located in the vicinity of the link path provide a measure of the ‘ground truth’ rainfall. shown that the microwave link gives valuable information to improve the radar rainfall estimates of the X-band radar.