The ASOS Climate Data Continuity Project: Its Beginnings and a Few Conclusions

Applications and other aspects of climatology are becoming increasingly dependent on automated measurements. In the United States, the Automated Surface Observing System (ASOS) is now the main source of surface observations from commissioned National Weather Service (NWS) and Federal Aviation Administration sites. The development of ASOS in the late 1980s generated concerns about the future among many climatologists and other retrospective users of surface observations. Particular concerns included comparability, stability, and accessibility of the new observations. The ASOS Climate Data Continuity Project (CDCP) was established in the early 1990s to help answer concerns about data from the imminent changes in temperature, precipitation amount, and wind speed sensors. Results of CDCP data intercomparisons have been presented annually during the 1990s at American Meteorological Society and other meetings, and separate summary papers are planned for this Conference. Complementing NWS-directed engineering and field evaluations, the CDCP helped identify some deficiencies that were overcome by development and installation of engineering modifications to particular subsystems. The combined efforts have evolved into a current NWS program of ASOS planned product improvements including eventual procurement of an all weather precipitation accumulation gauge as well as improved wind and dew point sensors. In addition to specific findings about ASOS data, CDCP project experience brings forth a few suggestions for the future. A primary example is the need for more systematic and accessible site-specific metadata pertaining to relocation and modification of existing and future automated observing systems. Other suggestions are more general and complement certain recommendations of a 1999 National Academy Press booklet entitled A Vision for the National Weather Service, Road Map for the Future.