The CLIMAT reports describe monthly climate observations by WMO (World Meteorological Organisation) Climate Reference Stations of which there are currently 20 in the UK and some 400 worldwide. The observation stations measure parameters such as monthly mean air temperature, monthly mean vapour pressure, total sunshine for the month, and total precipitation for the month. NOTE - these data are provided as-is from the Met Office and so will need converting form the CLIMAT message format.

The ship based SYNOP messages measurements describe hourly observations from sea based stations (ships, rigs, platforms and moored buoys) distributed globally. The observations cumulate in around 10,000 reports a day, giving measurements of parameters such as wind speed and direction, maximum and minimum air temperature, sunshine duration, rainfall accumulation, and cloud type. The data are collected by observation stations worldwide and transmitted within the ship SYNOP message.

The ozone satellite data describe ozone measurements deduced from satellite data. The dataset contains atmospheric profiles of ozone concentrations. The data are measured by satellites and around 2700 observations are made per day.

The land based SYNOP messages measurements describe hourly observations from land stations distributed globally. The observations cumulate in around 60,000 reports a day, giving measurements of parameters such as wind speed and direction, maximum and minimum air temperature, sunshine duration, rainfall accumulation, and cloud type. The data are collected by observation stations worldwide and transmitted within the land SYNOP message. Data are extracted from the Met Office's MetDB system before being sent to CEDA for archiving. These extractions occur at the 4 principal synoptic periods (00-06, 06-12, 12-18 and 18-00 UT). The dataset contains a range of measurements including: - Wind speed and wind direction - Maximum and minimum air and grass temperature - Horizontal and vertical visibility - Snow depth - Dew-point temperature - Relative humidity - 3 -hour pressure change - Height and period of wind waves - Cloud height and type - Radiation in last 24 hours - Maximum gust period - Past and present weather - Rainfall accumulation - Precipitation amount - Sunshine duration The wind speed and vertical gust speed are given to the nearest metre per second, and the vertical gust acceleration to the nearest metre per second squared. 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 air temperature, grass temperature and dew-point temperature are measured in Kelvin. The cloud height, visibility, snow depth, and wind-wave height are given in metres. Sunshine duration is recorded over 24 hours and over one hour. For the former, the measurement is in hours, but for the latter the measurement is in minutes. 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. The relative humidity is measured as a percentage. Documentation and Links to further information and references (see linked documentation on this record): Some general information about surface station readings can be obtained from the abridged version of "MIDAS Data Users Guide", provided by the Met Office. This document describes the meteorological surface data in the Met Office Database - MIDAS. This guide is rich in information and is aimed at those with little familiarity with observing methods or instrumentation. Details of the WMO Meteorological codes used at weather observing stations (daily and hourly weather) explain the codes used in this dataset further.

PILOT reports describe measurements reported up to four times daily by radiosondes at worldwide fixed land stations. The dataset contains measurements of wind speed and direction. The data are measured from the surface to approximately 20-30 km and measurements are usually taken every 2 seconds. These data are provided as-is from the Met Office and so will need the message components bringing together for each ascent The PILOT data contain the following observations: Wind speed at standard pressure levels Vertical wind shear Maximum wind level The data comprise vertical profiles of temperature, dew-point temperature, wind speed and wind direction at standard and significant pressure levels. The standard pressure levels are 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20 and 10 hPa. Significant pressure levels are calculated according to the Met Office criteria and constitute levels at which significant events occur in the profile, e.g temperature inversions. The data are measured from the surface to approximately 20-30 km. Generally there are up to 4 ascents per day from each station, though some sites may only have 1 or 2 ascents. Ascent times are typically around 00, 06, 12 and 18 UT. A maximum wind level is defined as a level at which the wind speed is greater than that observed immediately above and below that level..

The Aircraft Meteorological Data Relay (AMDAR) measurements describe hourly observations from aircraft across the world during all stages of flight. The observations cumulate into 160,000 reports a day, giving measurements of parameters such as aircraft characteristics, wind speed and direction, degree of turbulence, and air temperature. The data are collected by observation stations worldwide and transmitted within the AMDAR message, which prior to March 1992, was known as ASDAR(Aircraft to Satellite Data Relay).

The METAR reports describe hourly observations from 562 observation stations across the globe, including 131 UK stations. The data are produced by Synoptic observations for aviation purposes, giving measurements of parameters such as cloud amount, wind speed and direction, visibility, present weather, and maximum gust speed. The data are collected by observation stations worldwide and transmitted within the METAR message.

The ozone profiler data describes weekly measurements reported by an ozonesonde at a fixed land station at Lerwick. The dataset contains atmospheric profiles of ozone concentrations. The data are measured from the surface to up to 40 km, and transmitted from the ozonesonde via a radio link to a ground receiving station.

TEMP records describes measurements reported up to four times daily by radiosondes at worldwide fixed land stations. The radiosondes measure parameters such as atmospheric pressure, temperature, humidity, and wind speed and direction. The data are measured from the surface to approximately 20-30 km, and measurements are usually taken every 2 seconds. These data are provided from the Met Office as-is requiring each message part to be brought together to form each profile.

The wind profiler observations describe hourly observations from around 400 Wind profiler stations distributed globally. The observations cumulate in around 10,000 reports a day, giving measurements of parameters such as the different components of wind velocity, and the standard deviations of vertical and horizontal wind speeds. The data are collected by observation stations worldwide and transmitted within the WINPRO message. Wind speeds are given to the nearest metre per second. Air temperature is measured in Kelvin. Precipitation amount is given in kilograms per metre squared. Air pressure is given in Pascals. Relative humidity is measured as a percentage.