Metop

Metop is a series of three polar orbiting meteorological satellites which form the space segment component of the overall EUMETSAT Polar System (EPS).

Metop NOAA orbits

The EPS programme consists of a series of three polar orbiting Metop satellites, to be flown successively for more than 14 years, from 2006, together with the relevant ground facilities.

Metop-A (launched on 19 October 2006) and Metop-B (launched on 17 September 2012) are in a lower polar orbit, at an altitude of 817 kilometres, to provide more detailed observations of the global atmosphere, oceans and continents. The two satellites will operate in parallel for as long as Metop-A's available capacities bring benefits to users. Metop-C is due to be launched in 2017.

Metop Satellites
Satellite Lifetime Position Services
Metop-A From 19/10/2006 Low Earth Orbit Global Data Service. Regional Data Service. Direct Readout Service. Real-time Imagery
Metop-B From 17/09/2012 Low Earth Orbit Global Data Service. Regional Data Service. Direct Readout Service. Real-time Imagery
Metop-C Due to be launched in 2017 Low Earth Orbit -

Metop carries a set of 'heritage' instruments provided by the United States and a new generation of European instruments that offer improved remote sensing capabilities to both meteorologists and climatologists. These instruments augment the accuracy of temperature humidity measurements, readings of wind speed and direction, and atmospheric ozone profiles.

Metop has brought about a new era in the way the Earth's weather, climate and environment are observed and has significantly improved operational meteorology, particularly Numerical Weather Prediction (NWP).

The data generated by the instruments carried by Metop can be assimilated directly into NWP models to compute forecasts ranging from a few hours up to 10 days ahead. Measurements from infrared and microwave radiometers and sounders on board Metop provide NWP models with crucial information on the global atmospheric temperature and humidity structure, with a high vertical and horizontal resolution.

EPS also ensures continuity in the long-term monitoring of factors known to play an important role in climate change, e.g. changing patterns in the distribution of global cloud, snow and ice cover, and ocean surface temperatures and winds.

The Infrared Atmospheric Sounding Interferometer (IASI) instrument has the ability to detect and accurately measure the levels and circulation patterns of gases that are known to influence the climate, such as carbon dioxide. The data collected by IASI has been feeds into the models, for the first time showing the variable global distribution of carbon dioxide as a function of seasons and circulation anomalies such as the Southern Oscillation and the North Atlantic Oscillation (NAO).

EPS is the European contribution to the Initial Joint Polar System Agreement (IJPS), an agreement between EUMETSAT and NOAA. Metop flies in a Low Earth orbit corresponding to local 'morning', while the US is responsible for 'afternoon' coverage.

The series will provide data for both operational meteorology and climate studies. The combination of instruments on board Metop has remote sensing capabilities to observe the Earth by day and night, as well as under cloudy conditions.

EPS Programme Background

EUMETSAT is responsible for coordinating all elements of the development, launch and operation of EPS satellites. This includes developing and procuring the ground segment; procuring the launcher and launch site, and operating the systems. Under the IJPS and Joint Transition Activities (JTA) agreement, EUMETSAT and NOAA have agreed to provide instruments for each other's satellites; exchange all data in real time, and assist each other with backup services. Other partners are European Space Agency and CNES.

The European and American satellites carry a set of identical sensors: AVHRR/3 and the ATOVS suite consisting of AMSU-A, HIRS/4 and MHS. NOAA provides most of the joint instruments on board the satellites and EUMETSAT has developed and provides NOAA with the Microwave Humidity Sounder (MHS).

In addition, the Metop satellites carry a set of European sensors, IASI, ASCAT, GOME-2 and GRAS, aimed at improving atmospheric soundings, as well as measuring atmospheric ozone and near-surface wind vectors over the ocean. They also carry the Argos Advanced Data Collection System (A-DCS).

NWP and satellites

The NWP process includes the assimilation of weather observations, including satellite data, to provide the starting conditions for a numerical weather forecast model. A NWP model permits a computer simulation of processes in the Earth's atmosphere, land surface and oceans, which control the weather. Once current conditions are known, from satellite and in-situ observations, the changes in the weather are predicted by the model. Models are run several times a day to produce weather forecasts for the coming days.

Satellite observations became useful for NWP in the 1970s. In 1990s raw satellite data began to be used by NWP models, because data assimilation systems had advanced enough to assimilate measurements of the radiation, emitted by the atmosphere at many infra-red and microwave wavelengths, directly into NWP models. This advance, plus improvements in the quality and range of satellite observations and scientists’ understanding of how to model them, means satellite data have now become vital and integral parts of the global observing system in all regions. Now, more than 90% of all observational data used in global NWP comes from satellites.

As well as seeing details which are not picked up by surface observations forecasters can now get a better idea of large-scale developments, such as hurricanes. Today satellite monitoring can pick up the evolution of a hurricane from before its birth, when it is just a weather feature over Africa. Through the use of satellite data in NWP, the location and intensity of the storm can be monitored, and timely warnings can be issued of where it will make landfall.

Metop makes a considerable contribution to Numerical Weather Prediction (NWP) skill at the UK Met Office, particularly in the Southern Hemisphere where surface observations are sparse. Metop's ATOVS (Advanced TIROS Operational Sounder) package makes a major contribution to this.

The graphic (right), taken from the Met Office’s Forecasting Research Technical Report, no. 562 — The impact of Metop and other satellite data within the Met Office global NWP system using an adjoint-based sensitivity method (PDF, 296 KB) — shows that Metop data account for 25% of the total impact of observations on reducing global forecast errors.

In a presentation in 2012 Dr John Eyre, Head of Satellite Applications at the Met Office, stated: “Satellite observations play a growing role in many aspects of the work of the Met Office. They are assimilated into NWP models, where their importance has increased in recent years to the extent that they now contribute more strongly to the level of skill obtained by short- and medium-range forecasts than ground-based observations.

"Multi-spectral imagery from geostationary satellites, at high resolution in space and time, and products derived from these images are essential inputs to nowcasting systems. Satellite data and products also support operational forecasters in other ways: by depicting the extent and the development of a range of meteorological phenomena, and by aiding assessment of weather developments at synoptic and sub-synoptic scales, and hence the reliability of the NWP models’ forecasts of these developments.”