A Fast Response Continuous Analyzer for Halogenated Atmospheric Tracers

Abstract

A fast response version of the continuous SF6 analyzer originally introduced in 1976 has been developed. The new continuous analyzer has a response time constant of 0.36 s, which is 4?30 times faster than previous analyzers. The very fast response of the new analyzer allows it to be used to investigate the fundamental nature of atmospheric turbulence and diffusion processes. The new design has been thoroughly tested in laboratory and field conditions over an ambient temperature range from 4° to 40°C and an elevation range of 265 to 2130 m above sea level. The reproducibility in the response of the new analyzer was approximately ±15% over a one-month period. In automobile and aircraft sampling platforms, the reproducibility in response was less than ±12% for periods as long as 7.5 h and elevation changes exceeding 1800 m. The rate of baseline change was <1 ppt min?1 in the laboratory, <10 ppt min?1 in an automobile platform, and 15 ppt min?1 in an aircraft platform. The size, weight, and power consumption of the present analyzer have been minimized to allow for convenient mobile operation of the instrument.