Control and Monitoring Instrumentation for the Continuous Measurement of Atmospheric CO2 and Meteorological Variables

Abstract

The NOAA/GMCC program was chartered to monitor the trends in those atmospheric constituents that can cause climate change. A four-observatory network was established, and a 15-year database has resulted for selected variables. At the inception, a central data-recording system was established at each observatory using minicomputers to compress and record the signals from monitoring instrumentation onto a computer-compatible magnetic tape. A distributed recording system using Z80 microprocessors has recently been developed to replace the minicomputer system. The STD BUS was selected as a means of internal computer communication, thus allowing a modular design that was tailored to the specific instrumentation. The resulting Control And Monitoring System (CAMS) operates an interactive multitasking version of FORTH as the operating system software. Separate versions of CAMS were built to control and monitor the carbon dioxide analyzer, aerosol and solar radiation instrumentation, and meteorological and surface ozone instrumentation. Subsequently, 20 CAMS were assembled and tested and deployed at the observatories. Early results show that CAMS recovers very well from power outages, resulting in minimum data losses. Furthermore, by distributing the system, it has been possible to reduce significantly electromagnetic noise pickup at the input. The quality of the recorded data is significantly improved in comparison with open-reel, computer-compatible tapes. All factors have contributed to better data quality.