Simple Adjoint Retrievals of Wet-Microburst Winds and Gust-Front Winds from Single-Doppler Radar Data

Abstract

The simple adjoint method for retrieving the low-altitude winds from single-Doppler scans is modified and tested for two events: the wet-microburst event and the gust-front event observed simultaneously by two radars during the Federal Aviation Administration?1990 summer field experiment at Orlando Airport. For the wet microburst, 42 consecutive wind fields are retrieved from each radar and the rms errors (measured by the rms difference between the retrieved and dual-Doppler analyzed winds) range from 1.1 to 4.9 m s?1, and the averaged error is 2.4 m s?1. For the gust front, 22 consecutive wind fields are retrieved from each radar, the rms errors range from 1.2 to 2.9 m s?1, and the averaged error is 1.9 m s?1. The rms error and spatial correlation between the retrieved and analyzed cross-beam tangential winds exhibit strong temporal variations for the wet microburst and moderate temporal variations for the gust front. The rms error is found to be temporally correlated to the rms amplitude of the retrieved radial-momentum forcing for the wet microburst.