William Brune
The hydroxyl radical (OH) is an important oxidant in Earth's atmosphere, but measurement of its minuscule abundance is very difficult. In his Perspective, Brune provides an updated look at recent measurements carried out in Germany in which two different techniques were compared.
The author is in the Department of Meteorology, Pennsylvania State University, University Park, PA 16802, USA. E-mail: brune{at}ems.psu.edu