The Brewer Spectrophotometer

In the late 1960s and early 1970s, concerns were raised regarding the vulnerability of stratospheric ozone to anthropogenic activities and the consequential increase of ultraviolet-B (UVB) radiation at the earth's surface. These concerns prompted the development of new scientific instrumentation for monitoring the state of the ozone layer and levels of surface UV radiation. Included in the list of instrumentation is the ground-based Brewer spectrophotometer. The Brewer spectrophotometer has now been in operation at some sites for more than 25 years and has participated in numerous specialized field campaigns. Site instruments have been stable over long periods of time and function reliably in unattended operation for periods of several days under a wide range of operating conditions. The Brewer spectrophotometer has proven to be a valuable scientific tool that has made significant contributions to our understanding of the ozone layer and the dependence of surface UV radiation on stratospheric ozone and other atmospheric variables. This chapter discusses the history of the development of the Brewer spectrophotometer, describes the design and operation of the instrument, outlines the methods and algorithms used to measure the geophysical variables, and reviews some scientific results of operational and specialized measurements.