Ground-Based Radar Technologies for Tornado Observations

Abstract

Ground-based radar technologies have made a tremendous impact by revealing the three-dimensional structure of winds and precipitation in tornadic storms and tornadoes. In this chapter, a historical perspective on ground-based radar technology is presented, including the exciting technological evolution from early weather radars that observed the first hook echoes to modern-day polarimetric and phased array radar technology capable of scanning storms in less than 10 s. Early radar studies revealed the importance of Doppler radar capabilities, and led to implementation of a nationwide operational Doppler radar network that substantially improved tornado warning lead-time and accuracy. Scientists have used ground-based radars extensively in field studies of tornadoes and tornadic storms, including mobile radar systems that allow scientists to get very close to storms to obtain very high resolution data. These field studies include large-scale field experiments such as the first and second Verification of the Origins of Rotation in Tornadoes EXperiments (VORTEX), which deployed a network of mobile radars with a suite of other instruments. From the combined efforts of scientists and engineers to develop ground-based radars and conduct field experiments, new scientific discoveries have transformed our understanding of tornadoes and tornadic storms. By combining data from multiple radars, scientists have developed an understanding of the three-dimensional flows with supercells and tornadoes, and documented how changes in the storm-scale flow impact tornadoes and their formation. Rapid-scan radar data have shown that tornadoes can form or dissipate in less than 1 min, and that the tornado’s intensity and three-dimensional structure can drastically change in 10 s or less. Using dual-polarization radars, new capabilities have emerged to detect tornado debris remotely and infer tornado intensity and storm-scale processes. Exciting mobile radars and operational radar prototypes are under development that will provide both rapid-scanning and dual-polarization capabilities. These new radar systems will have a critical role in helping scientists discover the missing pieces in our understanding of tornadogenesis and tornado dynamics, and will continue to improve tornado warning performance to better protect society.