Estimating the impact of a 3-dB sensitivity loss on WSR-88D data

The planned upgrade of the WSR-88D network to include dual-polarimetric capabilities is expected to result in a loss of about 3 dB in sensitivity per channel. In order to better estimate the impact of this sensitivity loss, case study and real-time simulations were performed.

Algorithm products and base data from six archive WSR-88D cases were examined. The proportion of reflectivity samples lost upon desensitization was calculated, and the visibility of important meteorological features and velocity dealiasing errors before and after the desensitization were noted. Changes in the outputs of the echo top, hail detection, and legacy mesocyclone algorithms were observed. Changes to the output of the VAD wind profile (VWP) algorithm were measured. These results are presented.

In addition, a 3 dB higher threshold then usual was applied to KTLX WSR-88D data to simulate the signal loss. This data was then made available to National Weather Service forecasters for a side-by-side evaluation during the spring 2005 convective season. Forecaster feedback was compiled to estimate the impact of the sensitivity loss on situation awareness and decision-making, and these results are discussed.

An overview of proposed mitigation techniques to recover some of the lost velocity information is presented.