Accounting for Attenuation of X-Band Dual-Polarization Radar Data Due to Radome Wetting

X-band radars are growing in popularity as low-cost alternatives to larger radars for applications such as urban hydrology and gap filling for example. Due to their short wavelength such radars are prone to signal attenuation due to attenuation during periods of precipitation. While methods have been proposed to adjust for attenuation using dual-polarization fields, one major problem that requires attention is how to handle the data from the radar when it is suffering from attenuation due to the wetting of the radome. Using the MZZU dual-polarization radar situated outside of Columbia, MO, the authors are attempting to account for this type of attenuation issue.

The first step in the process has been the development of a radome attenuation detection algorithm based on radial reflectivity gradients. Once the attenuation has been detected attenuation is adjusted for by blending nowcast fields produced using the radar time series prior to the onset of radome wetting. Post-processing is also achieved by using ‘hindcasting’ reflectivity fields to blend a backward extrapolated field once the heavy precipitation has passed the radar.

The process produces good results for systems with coherent structures such as linear convective systems that pass over the radar, but has less success when the convection is disorganized.