SYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically sent every six hours by Deutscher Wetterdienst on shortwave and low frequency using RTTY. A report consists of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. It can be decoded by open-source software such as seaTTY, metaf2xml or Fldigi. SYNOP information is collected by more than 7600 manned and unmanned meteorological stations and more than 2500 mobile stations around the world and is used for weather forecasting and climatic statistics. The format of the original messages is abbreviated, some items are coded. Message format Following is the general structure of a SYNOP message. The message consists of a sequence of numeric groups, which may also contain slashes (indicating missing data) in addition to numeric digits. Leading numbers are fixed group indicators that indicate the type of observation following, and letters are replaced with numbers giving the weather data. Messages from shipboard weather stations, and in different regions of the world, use variations on this scheme. YYGGiw IIiii iRiXhVV Nddff (00fff) 1snTTT 2snTdTdTd 3PoPoPoPo 4PPPP 5appp 6RRRtR 7wwW1W2 8NhCLCMCH (9GGgg) YYGGiw: the date and time of the observation; YY for the day of the month, GG for the hour of the observation in UTC; iw for the manner of wind observation (a code number: 0 for estimated wind speed in meters per second, 1 for measured wind speed in meters per second, 2 and 3 likewise but in knots, or slash for no wind speed observations). IIiii: weather station identification code; II for a block number allocated (by the WMO) to a country or a region of the world, for example 02 for Scandinavia or 72 and 74 for the continental US; iii is the code of an individual station within a block. (For example, 02993 is the code of the weather station on Märket, 74794 of Cape Canaveral). iRiXhVV: iR indicates whether precipitation data is included or omitted. This is a code number from 0 to 4, with 0, 1 and 2 meaning data is included, and 3 and 4 indicating no precipitation data. iX is a code number indicating the manner of station operation, and the format used in group 7wwWW; codes 1,