Automated Meteorological Data Acquisition System

AMeDAS (Automated Meteorological Data Acquisition System), commonly known in Japanese as 'アメダス' (amedasu), is a high-resolution surface observation network developed by the Japan Meteorological Agency (JMA) used for gathering regional weather data and verifying forecast performance. The system began operating on 1 November 1974, and currently comprises 1,300 stations throughout Japan (of which over 1,100 are unmanned), with an average separation of 17 km (11 mi). Observations at manned stations cover weather, wind direction and speed, types and amounts of precipitation, types and base heights of clouds, visibility, air temperature, humidity, sunshine duration, and atmospheric pressure. All of these (except weather, visibility and cloud-related meteorological elements) are observed automatically.