Chilbolton Atmospheric Observatory, formerly known as the Chilbolton Facility for Atmospheric and Radio Research (CFARR), is hosted by the Science and Technology Facilities Council (STFC) in rural Hampshire in the South of England. Through a combination of long-term observations and tailored operations it provides national capability for the study of clouds, rainfall, boundary-layer processes and aerosols, and is particularly well suited as a site for hosting field campaigns involving visiting instruments.

The CAO site is located one mile south of Chilbolton Village, 6 miles south of Andover, Hampshire. The site was used as an airfield during the Second World War and is relatively flat and slightly elevated above the surrounding area.

The observatory operates more than twenty major instruments, many continuously, while others are available on-demand according to user configuration requirements. The portfolio includes a powerful combination of dual-polarisation Doppler radars, lidars, radiometers, and supporting instruments; the continuous round-the-clock operation of lidar and cloud radar instruments at Chilbolton is unique within the UK. These are supplemented by a suite of meteorological instrumentation including rain gauges, and disdrometers. A multi-wavelength sun photometer provides continuous measurements of aerosol optical depth in clear skies, and contributes to the Aerosol Robotic Network (AERONET).

The Chilbolton Advanced Meteorological Radar (CAMRa) is mounted on a 25-metre, fully steerable antenna, and is able to probe clouds and storms with unparalleled sensitivity and resolution. In addition, zenith-pointing polarimetric, Doppler 35 GHz and 94 GHz cloud radars are routinely operated for detailed microphysical studies of cloud processes and cloud climatology. A transportable, scanning 35 GHz cloud radar system is also hosted at Chilbolton, further enhancing the available capability.

Chilbolton was one of the pilot cloud profiling sites for the CLOUDNET project, and continues to make observations that feed into the Aerosol Clouds and Trace Gases Research Infrastructure (ACTRIS). Capability at the site will be enhanced in the next few years, with the incorporation of a Raman lidar, with the ambition being for this to form an ACTRIS observational platform for aerosol profiling.

The presence (since January 2016) of a Defra air quality monitoring supersite at the observatory site (providing rural background measurements as part of national and transboundary networks) offers the research community further excellent opportunities for intercomparison campaigns and instrument evaluation.

WIGOS id:
0-826-300-3
0-826-300-4
0-826-300-5

The Met Office also operated a boundary layer wind profiler at the site (now operated by NCAS AMOF), for which the site was given a WMO ID 03754.