Robust Attenuation Correction System for Radar Reflectivity and Differential Reflectivity

Accurate attenuation value retrieval without radar bias interference

At a Glance

​Researchers at Colorado State University have developed a robust attenuation correction system (ACS) for dual-polarization radars correcting the reflectivity factor as well as differential reflectivity profiles. The major advantage of the algorithm developed here is that the procedures are immune to the bias effect of reflectivity and differential reflectivity. In addition, this method is not very sensitive to the variation of temperature.

The ACS has been evaluated with X-band radar observations simulated from drop size distribution derived from high-resolution S-band measurements observed by the CSU-CHILL radar. Evaluation of the retrieval algorithm shows that the retrieved reflectivity and differential reflectivity provide an improvement over the conventional self-consistent attenuation correction technique with the differential phase constraint.

Overview

The monitoring of precipitation using higher frequency radar system such as the X-band has become more common in the last decade. At X-band frequency, weather radar signals are attenuated along their paths due to precipitation. For any quantitative applications that use reflectivity and/or differential reflectivity, they need to be corrected for attenuation effects due to precipitation.  A number of different theoretical models are available to mathematically describe the particle drop shape that influences attenuation estimation.

Each of these models has proven effective in different scenarios. It can be difficult, however, to predict which model to use. The total differential phase gives an idea of the attenuation, but it depends on the model. Moreover, the total attenuation along a rain path must be apportioned to different parts of the radar path in order to correct for attenuation along a radar path.

Benefits

  • Immune to the bias effect of reflectivity and differential reflectivity
  • Not sensitive to temperature variations or drop shape
  • Returns radar attenuation values that are immune to or independent from radar bias
  • System is far more robust and significantly more accurate than previous systems
  • System allows for the optimization of a number of different theoretical models for both drop size and temperature

Applications

Attenuation correction system for weather radars

Last Updated: May 2023
CSU CHILL Radar
IP Status

EP Patent: EP2834662 (DE)

Inventors

V. Chandrasekar
Sanghun Lim

Reference Number
12-067