pollutants and their typical health effects are shown in the following table. IPCC Until 2001 the Met Office hosted the Intergovernmental Panel on Climate Change working group, chaired by John Houghton, on climate science. In 2001 the working group moved to the National Oceanic and Atmospheric Administration. High performance computing Due to the large amount of computation needed for Numerical Weather Prediction and the Unified model, the Met Office has had some of the most powerful supercomputers in the world. In November 1997 the Met Office supercomputer was ranked third in the world. Customer service Since 2012 the Met Office Contact Centre (known as the Weather Desk) has been part of Contact Centre Panel's 'Top 50 Companies for Customer Service' programme. In 2015 the Met Office won awards in the following categories: Rated 1st Overall for Combined Channels Most Improved Overall for Social Media Rated 2nd Overall for Call Service Rated 1st Overall for Email Service Best in Public Sector Best Extra Small Centre Weather stations Reports (observations) from weather stations can be automatic (totally machine produced), semi-automatic (part-machine and part manual), or manual. Some stations produce manual observations during business hours and revert to automatic observations outside these times. Many stations feature "present weather" sensors, CCTV, etc. There is also a network of 'upper air' stations, using radiosondes. The six main radiosonde stations in the UK are Camborne, Lerwick, Albemarle, Watnall, Castor Bay and Herstmonceux. Some stations have limited reporting times, while other report continuously, mainly RAF and Army Air Corps stations where a manned met office is provided for military operations. The "standard" is a once-hourly reporting schedule, but automatic stations can often be "polled" as required, while stations at airfields report twice-hourly, with additional (often frequent in times of bad weather) special reports as necessary to inform airfield authorities of changes to the weather that may affect aviation operations. Some stations report only CLIMAT data (e.g. maximum and minimum temperatures, rainfall totals over a period, etc.) and these are usually recorded at 0900 and 2100 hours daily. Weather reports are often performed by observers not specifically employed by the Met Office, such as Air traffic control staff, coastguards, university staff and so on. Eskdalemuir Observatory Lerwick Observatory Penkridge weather station Prestatyn weather station Stonyhurst Sutton Bonington Wye weather station RAF Benson RAF Brize Norton weather station RAF Coningsby RAF Cottesmore RAF Cranwell weather station RAF Kinloss weather