The OH radical is central to the photochemistry of the troposphere, and measures of its concentration furnish an extremely sensitive test of our knowledge of the chemistry. Its detection, however, poses a considerable challenge due to its very low concentration and possible interfering species. At this time, there are several promising candidate methods, some ready for field trials and others not yet developed. SRI International will organize and host a workshop in early 1992 to assess current capabilities, discuss and thereby improve the experimental approaches, and consider intercomparison test. HO2 detection is not so difficult as HO detection but is also challenging, and discussion of its measurement using similar or variant methods will also be included. The workshop participants will include atmospheric modelers, researchers involved in field measurement and the associated technique development, and experimentalists in chemical physics. A report will be written describing the workshop discussions, conclusions, and recommendations.
