A total solar eclipse traversed the continental United States on 21 August 2017. It was the first such event in 99 years and provided a rare opportunity to observe the atmospheric response from a variety of instrumented observational platforms. This paper discusses the highquality observations collected by the Kentucky Mesonet (www.kymesonet.org), a research-grade meteorological and climatological observation network consisting of 72 stations and measuring air temperature, precipitation, relative humidity, solar radiation, wind speed, and wind direction. The network samples the atmosphere, for most variables, every 3 s and then calculates and records observations every 5 min. During the total solar eclipse, these observations were complemented by observations collected from three atmospheric profiling systems positioned in the path of the eclipse and operated by the University of Alabama in Huntsville (UAH). Observational data demonstrate that solar radiation at the surface dropped from >800 to 0 W m -2 , the air temperature decreased by about 4.5°C, and, most interestingly, a land-breeze-sea-breeze-type wind developed. In addition, due to the high density of observations, the network recorded a detailed representation of the spatial variation of surface meteorology. The UAH profiling system captured collapse and reformation of the planetary boundary layer and related changes during the total solar eclipse.

While sharing many common qualities in design and operation, mesonets across the United States were established independently and organically over the last several decades. In numerous instances, the unique ways each network matured and developed new protocols has led to important lessons learned. These experiences have been shared in informal ways amongst various network operators over the years to promote reliable operation. As existing networks begin to introduce new sensors and technologies, and as new networks come online, there is a common need for guidance on best practices. This paper aims to formally provide recommendations to improve and harmonize the various aspects of operating a mesonet, including siting, sensors, maintenance, quality assurance, and data processing.

The Kentucky Mesonet is a research-grade weather and climate observing network with redundant sensors that monitors the near-surface atmosphere at 71 locations across Kentucky. The network measures temperature, precipitation, solar radiation, relative humidity, barometric pressure, and wind speed and direction every 5 min, with soil moisture and soil temperature measured every 30 min. In addition, it operates a camera at selected locations. All observations are transmitted via cellular modem every 5 min and become available to the general public through the World Wide Web within seconds after arrival at Kentucky Mesonet’s Network Operations Center. In between arriving at the IT division and dissemination to general public, the data also go through automated data quality assurance (QA) procedures. Within that time, the data can be viewed through various graphical/visualization formats, developed based on feedback from the user community. The Kentucky Mesonet produces twice-daily QA reports and its technicians respond to these reports, making site visits when necessary to address issues. Mesonet technicians make regular site visits to all stations during spring, summer, and fall seasons. The network maintains a detailed database of station metadata that includes instrument and site maintenance history. The Mesonet delivers the data to the National Weather Service to aid forecasting. It also works closely with a variety of local, state, and federal entities so that the network can meet diverse needs.

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