The Met Office, UK, has been automating its upper air observation network for several years. This has involved new ground stations for the radiosonde system. A test and development program for radiosonde relative humdity measurements is being pursued with Vaisala Oy. Sensor performance has been evaluated against chilled mirror hygrometers in the UK and tests at Ascension Island and the WMO radiosonde test in Brazil. Results from these tests will be outlined and the expected method of resolving the discrepancies in operational measurements will be identified.

Automation includes deployment of remote sensing systems to augment the remaining radiosonde stations. A network of GPS sensors is being implemented and examples of where these observations are expected to be most useful in UK conditions will be shown, both from real-time observations and from analyses of water vapour structure postprocessed from non- Met Office GPS sites.

A small network of operational windprofiler sites has been established, and initial test results will be shown where microwave radiometer observations are compared with profiler signal to noise, cloud radar observations and GPS water vapour measurements from the Camborne test site, situatedclose to the Atlantic in the southwest of the UK.