The global marine meteorological observations data contains marine meteorological values, such as wave heights and periods, wind speed and direction, present weather, and air and sea temperature, measured during the hour ending at the stated date and time. The data is collected by worldwide observation stations and transmitted within the following message types: Ship SYNOP, which is also referred to as FM 13-IX SHIP, FM 18-X BUOY, Light Vessel, Marid, Marine logbooks, NAVY, OWS, PLAT/RIG, and VOF. In this dataset the different message types are all described by the SHIP message name. Data is available from 1854 to present.

The data consist of:

Offshore wind (speed and direction)
Weather (present, past)
Cloud (amount, type, base amount, base height)
Pressure (mean sea level)
Visibility
Temperature (air, dew-point, wetbulb, sea)
Relative humidity
Wave (direction, period, height)
Wind-wave (period, height)
Swell (direction, -wave period, height)
Ship direction and distance
Maximum gust speed and period

The wind speed is given to the nearest knot, direction to the nearest 10 degrees, and the time of the maximum gust is given to the nearest 0.1 hour. The wind direction from which the wind blows, is measured in Degrees (true). The entry for an east wind is 090, for a south wind it is 180 and so on clockwise. Note that zero values in both wind speed and wind direction fields indicate that there was no wind blowing at the time of observation.

The temperature and dew point are given to the nearest 0.1 degree Celsius, the pressure is given to the nearest 0.1 hectopascal, the cloud base height and the visibility are given to the nearest decametre. Cloud amount is reported in oktas.

The past weather is recorded as a number between 0-9 which details what the weather has been like in the last 6 hours for observations at 00, 06, 12, 1800 UTC, the last 3 hours for observations at 03, 09, 15, 2100 UTC and the previous hour at any other times. The past weather is only recorded when a manual observation is done at the station.

Marine reports are defined by position (latitude and longitude) and by time. Duplicates can exist at a specified position and time, e.g. when ships are alongside for bunkering, so the identifier of the ship or buoy is part of the primary key of the entity.

A great many ships do not include a valid call sign in their reports; the call sign may be missing or invalid. When this occurs, Midas will substitute the call sign value “SHIP”.