Met Office Cardington: column integrations of liquid water and water vapour from a Radiometrics WVR-1100 microwave radiometer, 2002-2022

The Met Office Observation-based research Boundary Layer Facility, at the semi-rural field site (18 Ha) of Cardington (52° 06′ N, 00° 25′ W, 29 m ± 1 m amsl) in central-southern England between 2004 and 2024, operated the Radiometrics WVR-1100 passive microwave radiometer measuring the atmospheric emissions at two frequencies (23.8 and 31.4 GHz) which provided brightness temperature at these channels, retrieve column integrations of liquid water path and integrated water vapour.

The WVR-1100 used a bi-linear regression method based on local radiosonde launches to retrieve column integrations of liquid water and water vapour. The WVR-1100 in addition performed ‘tipping curve’ observations using off-zenith slant scans where the optical depth for each frequency varies in a known way with atmospheric geometrical thickness. Tipping curves assume the atmosphere is horizontally homogeneous. The overall error in liquid water path is estimated to be 0.015 kg m-2. Water vapour and liquid water column amounts were logged typically every 9-10 s. Absolute calibrations for the absorbing channels were done periodically using an external black body cooled with liquid nitrogen.

A full list of NetCDF variables can be found in “A continuous hydrometeorological record (2004–2024) at the Met Office surface site of Cardington, UK.” Osborne et al. (2025). This paper should be referenced in any research/publications pertaining to this dataset.

To ensure optimal traceability and transparency of data, comprehensive metadata is included.