In June 2006 the NERC-funded Network for Calibration and Validation of EO data (NCAVEO) organised a cal-val field experiment in Chilbolton, north Hampshire involving 48 scientists from 20 organisations (click for list). The aim was to undertake a validation exercise based on the protocols and methods developed by the Validation of Land European Remote Sensing Instruments (VALERI) project, but modified as necessary for UK conditions. The experiment is a scoping exercise for the establishment of one or more VALERI sites in the UK as well as an opportunity to learn and share best practice amongst NCAVEO partners and the wider community. The initial plan was to base the experiment at the Barton Bendish test site in East Anglia, but the absence of on-site instrumentation coupled with uncertainty about access to this site and its distance from the main research groups led to a search for other suitable sites. The one chosen was centred on the Services and Technology Facilities Council Chilbolton Facility for Atmospheric and Radio Research (CFARR), approximately 45 km north of Southampton (Figure 1). CFARR comprises a number of state-of-the-art instruments for measuring atmospheric properties, including the 25 metre diameter Chilbolton dish, a 3 GHz doppler-polarisation radar, 1275 MHz clear air radar and a UV vertical sounding LiDAR In addition, the site has a full suite of continuously operating meteorological instruments. Datasets collected include Digi HRG data, remotely sensed data from 2 aircrafts, ground spectral data , atmospheric data, biophysical data, and fluvial geomorphological data.

The Icelandic Volcano, Eyjafjallajokull, started erupting on 14th April 2010. The volcanic ash cloud produced covered much of Northern Europe for several weeks causing extensive disruption to air travel. The UK and European atmospheric communities had many instruments - both airborne and ground-based, remote sensing and in-situ - taking measurements of the ash cloud throughout this period. This dataset contains Leosphere and Halo Doppler Lidar images from the Chilbolton Observatory, Hampshire.

Data were collected by the Chilbolton Facility for Atmospheric and Radio Research (CFARR) Meteorological Sensor from 2003 to 2007 at Sparsholt College, Hampshire. The standard meteorological measurements were made in support of all experiments at the Chilbolton Observatory. The data are automatically recorded every 10 seconds from a range of different sensors. The dataset contains measurements including temperature, dew point, pressure, wind speed and wind direction.

Data were collected by the Chilbolton Facility for Atmospheric and Radio Research (CFARR) Meteorological Sensor from 2001 to present at Chilbolton, Hampshire. The standard meteorological measurements are made at Chilbolton in support of all experiments at the Observatory. The data are automatically recorded every 10 seconds from a range of different sensors. The dataset contains measurements including temperature, dew point, pressure, wind speed and wind direction.

Data were collected by the Chilbolton Facility for Atmospheric and Radio Research (CFARR) Radiometrics Radiometer from the 23rd of August 2007 to the present at Chilbolton, Hampshire. The dataset contains measurements of the total liquid water at zenith, together with the vertical profile of water vapour density. Accuracy of integrated water vapour (IWV) retrieval: ~1 – 2 mm Accuracy of total liquid water path (LWP) retrieval: ~15% in non-precipitating conditions.

The Sparsholt College-South Wonston water station radio links data describe signal levels of several links at a frequency of 38 Ghz, which covered a path of 5km from the South Wonston water tower near the A34 to Sparsholt College. The data were collected between October 2002 and April 2005. The radio link between Sparsholt college and the Wonston water tower is used to investigate the effects of rain and sleet on radio signals.

Data were collected by the Chilbolton Facility for Atmospheric and Radio Research (CFARR) Present Weather Sensor from 28th of January 2005 to the 21st of May 2007 at Sparsholt College, Hampshire. The dataset contains reports of current weather conditions and those over the last hour using both NWS (National Weather Service)and WMO (World Meteorological Organistion) weather codes.

Data were collected by the Chilbolton Facility for Atmospheric and Radio Research (CFARR) Visible Radiometer from 10th of May 2001 to the present at Chilbolton, Hampshire. The dataset contains measurements of Calibrated brightness temperature measured at 21 frequencies (selectable) between 22.0 and 30.0 GHz, water vapour profile, and integrated water vapour (IWV). Data are produced once every approximately 2 minutes.

Measurements of tropospheric attenuation (excess and total) made at Sparsholt in Hampshire, UK using the ITALSAT satellite F1 beacon signal at 40 GHz.

Measurements of tropospheric attenuation (excess and total) made at Sparsholt in Hampshire, UK using the ITALSAT satellite F1 beacon signal at 20 GHz.