Wood, Jefferson, Scott, Carven, and Schneider, David, 2007, WSR-88D radar observations of volcanic ash: Fourth International Workshop on Volcanic Ash, World Meterological Organization (WMO) in close collaboration with the International Civil Aviation Organziation (ICAO) and the Civil Aviation Authority of New Zealand, Rotorua, New Zealand, 26-20 March, 2007, 9 p., available at http://www.caa.govt.nz/Volcanic_Ash_Workshop/Papers/VAWS4WP0403.pdf .