MEASUREMENT TECHNIQUES IN GAS-PHASE TROPOSPHERIC CHEMISTRY - A SELECTIVE VIEW OF THE PAST, PRESENT, AND FUTURE

Measurements of trace gases and photolysis rates in the troposphere ar e essential for understanding photochemical smog and global environmen tal change, Chemical measurement techniques have progressed enormously since the first regular observations of tropospheric ozone in the 19t h century. In contrast, by the 1940s spectroscopic measurements were a lready of a quality that would have allowed the use of modern analysis techniques to reduce interference between gases, although such techni ques were not applied at the time. Today, chemical and spectroscopic t echniques complement each other on a wide range of platforms. The boun daries between spectroscopic techniques will retreat as more Fourier t ransform spectrometers are used at visible wavelengths and as wide-ban d lidars are extended, and combining chemical techniques will allow de tection of more trace gases with better sensitivity. Other future deve lopments will focus on smaller, lighter instruments to take advantage of new platforms such as unmanned aircraft and to improve the effectiv eness of urban sampling.