The XEMA is the Network of Automatic Weather Stations managed by the Meteorological Service of Catalonia (SMC), and forms part of the Network of Meteorological Equipment of the Generalitat of Catalonia (XEMEC), as established by Law 15/2001, of 14 November 2001, on Meteorology.
The XEMA is currently made up (as of February 2010) of a total of 165 Automatic Weather Stations (EMAs) which transmit information to the SMC via digital radio, GSM technology and satellite. The fundamental difference between the EMAs is the altitude at which they measure the wind, as depending on their position and purpose the anemometer and wind vane could be positioned at 2, 6 or 10 metres in height. The height at which the wind is measured appears on the specifications of each station. From a meteorological point of view, the optimum height for measuring the wind is 10 metres, and the main reason for measuring it at 2 or 6 metres is because of the need to know the wind strength at these heights for a variety of specific reasons, such as calculating the risk of forest fires or the evapotranspiration of reference. · Table showing the county distribution of the XEMA · Map of the geographical distribution of the XEMA with the specifications relating to each EMA · Operating principles of the EMA sensors · Reduction of atmospheric pressure to a reference level
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