EUMETSAT Geostationary Meteorological Satellite ProgramsAbstract

EUMETSAT, the European Organisation for the Exploitation of Meteorological Satellites, operates a range of satellite programs, among them the Meteosat series of geostationary satellites which has provided continuity of coverage over Europe and Africa since 1977. Its current operational geostationary services are provided by the Meteosat Second Generation (MSG), consisting of the primary satellite, the Meteosat-9, the back-up and Rapid Scanning Service Meteosat-8, as well as the older generation Meteosat-7 satellite positioned over the Indian Ocean. It works closely in partnership with the European Space Agency and with NOAA in its programs. As a user-driven organization it places great emphasis on developing additional value from its products by sophisticated systems for processing of the satellite data, centrally at its headquarters in Darmstadt, and through a distributed network of Satellite Applications Facilities in its Member States. A successor program to the MSG, the Meteosat Third Generation, has been approved and will ensure coverage out to 2040.

Keywords Calibration - Climate monitoring - EUMETSAT - European Space Agency - Further processing - Geostationary - Instruments - Meteorology - Meteosat - National meteorological services - Numerical weather prediction - Radiometer - Satellite applications facilities - Satellites - Weather forecasting

Introduction

Since the launch of the first meteorological satellites by the United States in the 1960s, meteorologists around the world have made extensive use of the images and data available from them. Weather systems that previously had just been drawings on weather maps took on real shapes from the satellite images. As weather forecasting techniques developed, more sophisticated use of the satellite data became possible. Particular applications were the use of the data in Nowcasting, i.e., forecasting for the very short range up to 12 h ahead which relies heavily on observational data, and Numerical Weather Prediction techniques, mathematical models of the atmosphere which ingest observational data of many types, including numerical data derived from satellite instrument measurements, and then produce forecasts up to 10 days ahead.

Of paramount importance is the accurate monitoring and forecasting of severe weather situations to help save human lives and property. The ravages of weather-related disasters take a heavy toll of life around the world and the images available from geostationary meteorological satellites, with a frequent repeat cycle, are of huge value in the vital task of predicting such events and helping to mitigate their impacts.

While the primary justification for investment in a meteorological satellite program continues to lie in the benefits that it brings to operational weather forecasting, increasingly, the wider benefits of the programs for Earth observation of all kinds (including of the oceans, atmosphere, and land) and for monitoring of climate and of climate change add considerably to the value of the programs.

In Europe, EUMETSAT operates programs of meteorological satellites that benefit not only Europe but also Africa and other regions and forms part of a global satellite coverage with other satellite operators. EUMETSAT is an intergovernmental organization set up in 1986 to exploit the benefits of European operational meteorological satellite programs. Originally composed of 16 Member States, its membership had grown by the end of 2010 to 26 states. It also has five Cooperating States.

Current EUMETSAT Member States are: Austria, Belgium, Croatia, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, and the United Kingdom.

Cooperating States are: Bulgaria, Estonia, Iceland, Lithuania, and Serbia.

The impetus for the creation of EUMETSAT came from the national meteorological services of Europe. Originally the intention was that the organization would fund meteorological satellite programs (both geostationary and polar-orbiting) that would be defined jointly with the European Space Agency (ESA), which would then develop and operate the satellites, EUMETSAT gradually came to play a greater part in the specification of the space segment of the programs and set up its own ground station infrastructure to operate its satellites and to develop useful products from the satellite data.

EUMETSAT headquarters is located in Darmstadt in Germany. The Director-General reports to the EUMETSAT Council which is the governing body of the organization and consists of delegations from all Member States.

Overview of Past and Current EUMETSAT Programs

The history of European meteorological satellites began before the establishment of EUMETSAT with the launch by ESA of the first Meteosat geostationary satellite in 1977 as part of its activity to develop space applications. Meteosat-1, as it came to be called, gave Europe the ability to gather weather data over its own territory for the first time with its own satellite. The 800-kg first-generation Meteosat was followed by two other satellites in what is termed the preoperational series of Meteosat satellites. When EUMETSAT was formed it took over the funding of the Meteosat series for Meteosat-4, Meteosat-5, and Meteosat-6. The next in the series, Meteosat-7 was launched in 1997 and became the first satellite program to be devised and funded by EUMETSAT in what was called the Meteosat Transition Programme. The transition refers to the bridging of a gap between the older "first-generation" Meteosat satellites and the planned Meteosat Second Generation (MSG).

The first-generation Meteosat was equipped with the three-channel Meteosat Visible and Infrared Imager and a repeat cycle of 30 min. This system operated successfully since 1977 providing almost continuous images and other services to the National Meteorological Services of EUMETSAT Member States and brought major improvements to weather forecasting in Europe. Meteosat has also served operational and research users throughout West and East Europe and Africa, with many other users in North and South America, the Middle East, and even in the Arctic and Antarctic areas. Technological advances and increasingly sophisticated weather forecasting requirements created demand for observations to be more frequent, more accurate, and in higher resolution. To meet this demand, the scope and objectives of the Meteosat Second Generation (MSG) Program were defined in 1993 to form the basis of cooperative programs established at EUMETSAT and ESA.

On 28 August 2002, EUMETSAT launched the first MSG satellite (renamed Meteosat-8 when it began routine operations) from the Guiana Space Centre in Kourou, French Guiana, on board an Ariane rocket. It was followed on 21 December 2005 by the second MSG satellite, Meteosat-9 (Fig. 38.1).

Fig. 38.1 Launch of Meteosat-9 satellite from Guiana Space Centre, 21 December 2005

Current Status of EUMETSAT Programs

The operational geostationary meteorological satellite service over Europe is now exclusively provided by Meteosat Second Generation (MSG) satellites - Meteosat-8 and Meteosat-9. Together, the two satellites provide the operational service for Europe of a quality never before experienced from geosynchronous orbit. Follow-on satellites are scheduled for launch in 2012 and 2014 (www.eumetsat.int/home/main/satellites/MeteosatSecondGeneration; www.esa.int/esaMI/MSG).

Meteosat-9 provides the primary satellite coverage at a position above the equator at 0° longitude. Meteosat-8, situated at 9.5° East, is the backup for the primary satellite. The 15-

minute high-resolution image data generated by the operational Meteosat satellite, Meteosat-9, is complemented by the Rapid Scanning Service (RSS) of Meteosat-8. The RSS service was originally introduced in 2001 as a service that permitted more frequent imaging over a limited field of view. In the MSG era that imaging interval is 5 min, the same as European weather radars, allowing the monitoring of rapidly developing localized convective weather systems like thunder storms.

All MSG images and products are distributed via EUMETCast-Europe, EUMETSAT's broadcast system for environmental data, and on the Global Telecommunication System of the World Meteorological Organization (WMO) and are archived at EUMETSAT.

The first generation of Meteosat, however, is still providing an operational service through Meteosat-7, the survivor of that series following the retirement of Meteosat-6 in April, 2011. Meteosat-6 had set a record of more than 17 years for the duration of the operational life of a Meteosat satellite. Located at 57.5°E, Meteosat-7 provides the Indian Ocean Data Coverage (IODC) service. The operational service from this location began on 1 July 1998 and is currently planned to remain operational until the end of 2013. IODC data provide important information on monitoring cyclonic systems, dust storms, and other meteorological phenomena in the Indian Ocean region. As part of the IODC service, the Meteosat-7 satellite relays tsunami warnings covering the Indian Ocean region. As with all satellite data, the IODC data are also of value as input to numerical weather prediction systems.

Another major element of the EUMETSAT suite of meteorological satellites is the EUMETSAT Polar System (EPS) which currently has one polar-orbiting satellite, the Metop-A, in orbit. Together with the POES satellite operated by NOAA, the Metop-A provides a global coverage which greatly enhances the geostationary satellite activity. Two further satellites in the EPS program, Metop-B and Metop-C are due for launch in 2012 and 2016, respectively.

EUMETSAT is also part of a cooperation which operates an ocean altimetry satellite, Jason-2, which provides oceanographic and meteorological information. The other cooperation partners are NASA, NOAA, and the Centre National d'Études Spatiales (CNES,

the French Space Agency). A follow-on satellite (Jason-3) will be launched in 2013.

EUMETSAT Partnerships and International Cooperation

The geostationary satellite programs of EUMETSAT (and also its polar-orbiting satellites) are carried out in close cooperation with the European Space Agency (ESA), representing an efficient use of European resources and reflecting the complementary roles of the two organizations. ESA is committed to research and development rather than to operational systems but the development of the first satellite in a program falls naturally within its mandate (www.esa.int/esaMI/MSG). EUMETSAT is a user-driven operational agency. The usual formula for cooperation between the two organizations is for ESA to develop the first satellite, based on user requirements specified by EUMETSAT, with EUMETSAT also making some contribution to the costs. Development of new instruments (often pioneered on ESA research satellites) is also part of ESA's role. EUMETSAT covers the costs of recurrent satellites and provides the entire ground structure.

EUMETSAT also has close cooperation with the meteorological community, mainly through the World Meteorological Organization (WMO), the European Centre for Medium-range Weather Forecasts (ECMWF), and, of course, with the national meteorological services of its Member States and Cooperating States.

A close partnership exists with NOAA and manifests itself in the form of collaboration on the operational global polar-orbiting program and of a backup agreement between the two agencies that commits each side to help the other in the case of operational difficulty such as satellite failure.

EUMETSAT also has cooperation agreements with the other meteorological satellite providers and shares data with them.

It is also active in the international structures that facilitate cooperation in satellite meteorology. It is a member of the Coordination Group for Meteorological Satellites (CGMS) and, in fact, provides the secretariat for CGMS. It is also a member of the Committee for Earth Observation Satellites (CEOS) and contributes to other international activity such as the Group on Earth Observation

(GEO) and the European Union's Global Monitoring for Environment and Security (GMES).

The MSG Satellites: An Overview

The MSG system is designed to support weather forecasting in all ranges including Nowcasting (out to 12 h ahead), short-range forecasting (out to 2 days), medium range (out to 2 weeks). It makes a valuable contribution to numerical weather prediction through the numerical data that are derived from the satellite instruments. It also contributes to climate applications over Europe and Africa.

The mission objectives are:

Multi-spectral imaging of the cloud systems, the Earth surface, and radiance emitted by the atmosphere, with improved radiometric, spectral, spatial, and temporal resolution when compared to the first-generation Meteosat.

Extraction of meteorological and geophysical fields from the satellite image data for the support of general meteorological, climatological, and environmental activities.

Dissemination of the satellite image data and meteorological information, upon processing, to the user community in a timely manner.

Collection of meteorological and environmental data from Data Collection Platforms (DCPs), and its distribution to appropriate users.

Support to secondary payloads of a scientific nature (GERB) and to Search and Rescue (called GEOSAR). These payloads do not interfere with the primary objectives as laid out above (www.eumetsat.int/home/main/satellites/MeteosatSecondGeneration).

Like all geostationary satellites, the satellites in the MSG series are placed in orbit approximately 36,000 km above the equator to ensure that their orbits are synchronized with the Earth's movement and so have a fixed field of view of the Earth.

Meteosat Second Generation (MSG) consists of a series of four geostationary meteorological satellites, along with ground-based infrastructure, that will operate consecutively until 2020, with the possibility to extend until

2022. The main instrument carried by the MSG satellites is the imaging radiometer, the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), which has the capacity to observe the Earth in 12 spectral channels. In addition, a scientific research instrument, the Geostationary Earth Radiation Budget (GERB), is included in the payload. A Search and Rescue transponder, GEOSAR, is also supported on the satellites (Schmetz et al. 2002).

In common with other programs devised by EUMETSAT, the MSG program is a partnership between EUMETSAT and the European Space Agency (ESA). The role of EUMETSAT was to establish requirements for the space segment based on users requirements, ensuring the consistency between those requirements and the MSG satellites, to contribute one third of the MSG-1 (Meteosat-8 in-orbit) funding, to procure the MSG-2/3/4 satellites via ESA, to procure all launch services and all services for post-launch early operations, to develop the ground segment, and to operate the system.

ESA developed the MSG-1 prototype satellite according to EUMETSAT requirements and acted, on behalf of EUMETSAT, as procurement agent for MSG-2/3/4 satellites.

The prime contractor for the manufacture of the MSG satellites is Thalès Alenia Space, France. Astrium SAS manufactured the SEVIRI instrument, while a European consortium, led by the Rutherford Appleton Laboratory (RAL) in the United Kingdom, was responsible for the Geostationary Earth Radiation Budget (GERB) instrument.

Each MSG satellite was designed to remain in orbit in an operable condition for at least 7 years. The current policy is to keep two operable satellites in orbit and to launch a new satellite close to the date at which the elder of the two comes to the end of its onboard fuel. Starting toward the end of the MSG in orbit lifetime there will be a follow-on series in geostationary orbit, Meteosat Third Generation.

The SEVIRI instrument observes the atmosphere over 12 spectral channels with repeat cycles of 15 min in nominal mode and 5 min in rapid-scanning mode. There are 11 spectral channels observing the earth with a sampling distance of 3 km, generating full earth images. The last of the 12 spectral channels observes the earth with a sampling distance of 1

km, generating a partial view of the earth in the east/west direction, with the possibility of splitting the observed area at a programmable latitude such that the top and bottom areas can be shifted in the east/west directions from each other.

MSG's enhanced channel and scan capacity, with the ability to transmit more than 20 times the information at twice the speed of its predecessor has opened up a range of improved applications for users.

The enhanced imagery delivered by MSG provides detailed maps to support operational weather forecasts by, for example, improved animations of developing weather conditions, such as potentially hazardous fog banks around shipping lanes or storms on an airplane's flight path. MSG is also proving to be an invaluable tool for climate monitoring. Satellite observation of clouds, precipitation, and temperature provide valuable sources of data to climate researchers. MSG's ability to monitor atmospheric water vapor, dust, and surface features (such as the distribution of snow, ice and vegetation) is also proving to be essential in understanding the Earth's climate.

In order to operate the satellite and to collect data from it and to derive value-added products and to disseminate and archive the data, a sophisticated ground segment is a part of the program.

The MSG Space SegmentLike the previous generation of Meteosat satellites, MSG is spin-stabilized. When operating in geostationary orbit, the satellite spins counterclockwise at 100 rpm around its longitudinal axis, which is parallel with the Earth's rotational axis (Fig. 38.2).

Fig. 38.2 Schematic of the MSG satellite

The MSG body is cylindrical in shape, 3.2 m in diameter, and 2.4 m high, with the top antenna protruding to about 3.8 m. The satellite itself is built in a modular way around three main sub-assemblies:

The Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument in the central compartment

The Mission Communication Payload (MCP), including antennas and transponders, in the upper compartment

The platform support subsystems, in the lower compartment

For its initial boost into geostationary orbit as well as for station keeping, the satellite uses a bipropellant system. This includes small thrusters, which are also used for attitude control. The MSG solar array, built from eight curved panels, encloses the satellite body.

The satellite platform provides the necessary housekeeping functions for accommodation and service of the payloads (enabling control from the ground), for orbital motion and stabilization, and for energy supply.

The communications payload provides multichannel transponders and antennas for:

Downlink of onboard-generated payload data (within the raw data stream of approximately 3.3 Mbps) and onboard satellite monitoring data

Uplink of telecommands to the satellite

Relay of messages from DCPs to the MSG Ground Segment, of low rate information from the MSG Ground Segment to users, and of GEOSAR beacons

The Instruments

Spinning Enhanced Visible and Infrared Imager (SEVIRI)

As with all meteorological satellites, the principal instrument is the imaging radiometer which operates by collecting radiances from the Earth's surface and atmosphere.

On the MSG satellites, the radiometer is the SEVIRI which has 12 spectral channels (as opposed to three on the previous Meteosat systems), which provide more precise data throughout the atmosphere giving improved quality to the starting conditions for numerical weather prediction models (Schmid 2000).

The 12 SEVIRI channels consist of 8 infrared (IR) detector packages (3 detectors each), 2 Visible and 1 Near-IR (3 detectors each) and 1 High Resolution in the Visible (HRV) channel (9 detectors). The full list is:

Visible band centered on 0.6 μm

Visible band centered on 0.8 μm

Near-infrared band centered on 1.6 μm

Infrared band centered on 3.9 μm

Water vapor band centered on 6.2 μm

Water vapor band centered on 7.3 μm

Infrared band centered on 8.7 μm

Ozone band centered on 9.7 μm

Infrared band centered on 10.8 μm

Infrared band centered on 12.0 μm

Carbon dioxide band centered on 13.4 μm

Broadband high-resolution visible band

The operating principle of the SEVIRI is that a scanning mirror is used to move the instrument line-of-sight (LOS) in the south-north direction.

The target radiance is collected by the telescope and focused onto the detectors. Channel separation is performed at telescope focal-plane level, by means of folding mirrors. A flip-flop type mechanism is periodically actuated to place an IR calibration reference source in the instrument's field of view. The image data are directly transferred from the Main Detection Unit (MDU) to the satellite data-handling subsystem. The Functional Control Unit (FCU) controls the SEVIRI functions and provides the telemetry and telecommand interfaces with the satellite. The Earth imaging is achieved by means of a bidimensional Earth scan, relying on the spacecraft's spin and the scanning mirror. The rapid scan (line scan) is performed from east to west thanks to the spacecraft's rotation around its spin axis (spin rate 100 rpm). The spin axis is perpendicular to the orbital plane and is nominally oriented in the south-north direction. The slow scan is performed from south to north by means of a scanning mechanism, which rotates the scan mirror in steps of 125.8 μrads. A total rotation of the mirror of ±5.5° (corresponding to 1,527 scanning lines) is used to cover the entire field of view of the Earth plus margin, corresponding to 22° imaging range in the south-north direction, and 1,210 scan lines in the baseline repeat cycle.

The full Earth's disk image is obtained in about 12 min. The scanning mirror is then driven back to its initial position and the flip-flop mechanism is activated to insert a black body onboard the spacecraft into the optical path for the instrument calibration. The black body is removed from the calibration position after about 2 s and Earth observation is resumed, leading to an overall repeat cycle of 15 min.

From each channel geographical arrays of image pixels are received, each pixel containing 10 data bits, representing the received radiation from the Earth and its atmosphere.

The resulting data are buffered onboard and transmitted to the ground over a full revolution to moderate the downlink rate.

Using channels that absorb ozone, water vapor, and carbon dioxide, MSG satellites allow meteorologists to analyze the characteristics of atmospheric air masses making it possible to reconstruct a three-dimensional view of the atmosphere. The improved horizontal image resolution for the visible light spectral channel (1 km as opposed to 2.5 km on the previous system) also greatly aids weather forecasters in

detecting and predicting the onset or cessation of severe weather.

Calibration of the satellite instruments is a vital part of the entire process. The spectral response of an instrument is a measure of the instrument's response to radiation at specific wavelengths and spectral response characterization is the most crucial aspect of satellite calibration. The responses are nonlinear and may change over the lifetime of an instrument, making it necessary to correct for these changes after launch when producing images from the system. The accuracy of prelaunch spectral response characterization, and how well the on-orbit changes are understood, directly affects calibration accuracy and the quality of the data products. Even within the same satellite series, spectral response varies by instrument, sometimes dramatically. In fact, spectral response often varies by detector on the same instrument. Spectral responses are derived for all 12 channels of the SEVIRI instrument.

Geostationary Earth Radiation Budget (GERB)

In addition to the SEVIRI there is the Geostationary Earth Radiation Budget (GERB) instrument. The GERB is a visible-infrared radiometer for Earth radiation budget studies. It makes accurate measurements of the shortwave (SW) and longwave (LW) components of the radiation budget at the top of the atmosphere. It was the first Earth Radiation Budget experiment from geostationary orbit. The GERB provides valuable data on reflected solar radiation and thermal radiation emitted by the Earth and atmosphere (www.eumetsat.int/home/main/satellites/MeteosatSecondGeneration; Schmetz et al. 2002).

The GERB instrument is a scanning radiometer with two broadband channels, one covering the solar spectrum (0.32-4.0 μm), and the other covering a wider portion of the electromagnetic spectrum (0.32-40 μm). Together these channels are used to derive the thermal radiation emitted by the Earth in the spectral range 4.0-40 μm, as a difference between the two of them. Data are calibrated on board in order to support the retrieval of radiative fluxes of reflected solar radiation and emitted thermal radiation at the top of the atmosphere with an accuracy of 1%. The radiation budget represents the balance between incoming energy from the Sun and outgoing thermal (longwave) and reflected (shortwave) energy from the Earth.

Mission Communication Payload (MCP)

This package contains all antennas and transponders necessary to meet the demanding communication needs of the MSG mission. This includes telemetry, telecommanding and transmission relay links, in various frequency bands.

Search and Rescue Transponder

The satellite payload includes a transponder capacity for relay of distress signals. This is the Search and Rescue (GEOSAR) mission, which forms part of the International Satellite System for Search and Rescue (COSPAS-SARSAT). The Search and Rescue transponder receives distress signals from any mobile unit in difficulty within the MSG coverage zone in Europe, Africa, and the Atlantic Ocean.

The MSG Ground Segment

The functions of the MSG Ground Segment are to control and communicate with the satellites, to collect and validate the instrumental data, to enhance the value of the data by further processing, to disseminate the data to the users, and to archive them for future use by researchers.

The EUMETSAT MSG Ground Segment is made up of:

Centrally located facilities, at EUMETSAT headquarters in Darmstadt, Germany, for satellite control, preprocessing of data, dissemination, and archiving

Primary and backup ground stations

Product extraction facilities, consisting of the Meteorological Products Extraction Facility (MPEF) based in Darmstadt, and the network of Satellite Application Facilities (SAFs), distributed among the EUMETSAT's Member States

The Centrally Located Facilities

The Mission Control Centre (MCC) controls the EUMETSAT satellites through the relevant ground stations and preprocesses all data acquired from these satellites. Among its tasks are control of the satellite orbit, monitoring the status of the satellite through checking various characteristics such as temperature, fuel consumption, etc., and monitoring the ground stations. In general, it ensures that all aspects of the satellite performance are monitored, controlled and, if necessary, corrected by the initiation of commands that are relayed to the satellite by the ground stations. It also performs all operations necessary for satellite tracking and ranging. A team of operations personnel man the Mission Control Centre on a continual basis (Fig. 38.3).

Fig. 38.3 Mission control centre at Darmstadt

Raw sensor data are received from the ground stations and forwarded to the Image Processing Facility (IMPF). These level 1.0 data, as they are known, are then subject to further processing to generate level 1.5 data. In the case of Meteosat image processing, this entails line-by-line processing to ensure that imperfections are removed. In particular, the data from the various onboard sensors are realigned by resampling in order to make the image from each set of detectors coincide with the reference grid. At the same time, the sampling removes the slight perturbations caused by the movement of the spacecraft, and corrects for effects such as Earth's curvature and rotation, thereby rectifying the image so that it appears to come from the nominal location of the spacecraft (geometric correction). Further adjustments to the individual data values are made to correct for atmospheric effects and for sensor characteristics in accordance with calibration information (radiometric correction). Once each line of the level 1.5 products is complete, it is passed to the dissemination computers for immediate relay to users and to higher processing facilities, Meteorological Products Extractions Facility (MPEF) and the Satellite Application Facilities (SAFs).

Calibration is a vitally important aspect of operational meteorological satellite programs. In addition to prelaunch and initial orbit calibration of the instrument sensors, a routine calibration monitoring is performed for IR channels (using the internal black body of SEVIRI) and for visible channels (using vicarious calibration on dedicated stable earth targets). Based on the above calibration methods, radiometric corrective factors are used to generate the level 1.5 image from the level 1.0 image.

The Meteosat ground segment also supports the Global Earth Radiation Budget (GERB) mission, handling all communications with the instrument onboard the Meteosat, and the reception of raw GERB data. The GERB data are then sent to the central GERB ground segment at the Rutherford Appleton Laboratory (RAL) in the UK for processing and forwarding to other European institutions.

Another element of the MSG Ground Segment acquires Foreign Satellite Data and makes them available to the further processing systems or for dissemination to EUMETSAT users.

The GEOSAR Ground Segment has relayed to it messages from the COSPAS-SARSAT beacons on board the satellites. In this case the satellites act as simple transponders only.

The MSG Ground Segment is connected to the Global Telecommunication System (GTS) of WMO, so as to receive GTS messages for further dissemination or for use in the MPEF. It also ingests into the GTS network meteorological products produced by MPEF, as well as all international and selected regional DCP messages. The GTS connection is via the GTS Regional Telecommunications Hub at the Deutscher Wetterdienst in Offenbach, Germany.

The EUMETSAT data collection and dissemination systems are described below, as is the EUMETSAT Data Centre which archives images and meteorological products from all satellite programs, and provides access to these data to users via the EUMETSAT Portal.

The Ground Stations

A network of dedicated ground stations provides the communication channels between the satellites and the Mission Control Centre (MCC). The ground stations are an essential component of any satellite system and collect from the satellite all the information necessary for the assessment of satellite performance, as well as the scientific data from the instruments and they also relay command messages from the MCC to the satellite (Fig. 38.4).

Fig. 38.4 EUMETSAT ground segment

The Primary Ground Station (PGS) is located in Usingen, Germany, around 30 km north of Frankfurt. It provides the primary interface between the satellites and the Mission Control Centre (MCC), including all ranging functions and communications lines. The PGS is unmanned and can be remotely monitored and controlled from the MCC in Darmstadt. The Backup Satellite Control Centre (BSCC), which can assume the functions of the MCC in the case of emergencies, is also located at Usingen.

The prime transmission channel between the MCC and the PGS is a 34 Mbit/s microwave link with a terrestrial-based back-up link. To accomplish these vital tasks to the required reliability standard, a considerable amount of redundancy is incorporated in the station design, which, to a great extent, can function completely automatically.

Three fully steerable 13-m diameter parabolic antennas are located at the PGS and used exclusively to support all communications with the MSG satellites. Each antenna is capable of supporting all transmissions and data reception required for one spacecraft and is used for

telemetry and telecommands, raw image reception, collection of Data Collection System reports and for low-rate direct dissemination.

A Backup and Ranging Ground Station (BRGS) is located in Maspalomas, Gran Canaria Island, Spain. This location is sufficiently separated from the PGS to allow accurate ranging measurements to be made to determine the precise location and orbit of the MSG satellites. The BRGS is also dedicated to provide telecommanding and telemetry support to the ground network for the operations of the satellites in case of a complete system failure at the PGS. A further backup station is located at Cheia, Romania, to overcome outages of the station in Maspalomas caused by the atmospheric scintillation.

Product Extraction Facilities

As an organization created and funded by the European meteorological community, it is not surprising that EUMETSAT places a very strong emphasis on developing products, based on the satellite images and data, which are of direct benefit to its users. Consequently, a comprehensive range of meteorological and geophysical products is derived by EUMETSAT's Application Ground Segment, both at its headquarters in Darmstadt and through the distributed network of Satellite Application Facilities (SAFs) (www.eumetsat.int/home/main/satellites/MeteosatSecondGeneration).

All of these products are extracted on a fully automated basis requiring a minimum of human intervention and are distributed via the EUMETSAT data dissemination system, EUMETCast, the Internet, and other means.

The product extraction mission is performed within the MSG Ground Segment by a combination of the Meteorological Products Extraction Facility (MPEF) in Darmstadt and the network of Satellite Applications Facilities (SAFs) distributed around the EUMETSAT Member States. In addition to the products that are based on MSG data, both the MPEF and the SAFs also make extensive use of the data available from EUMETSAT's Metop polar-orbiting satellite.

The product extraction processing uses the level 1.5 image and supporting data acquired from Image Processing Facility, along with observed and forecast meteorological data

acquired from the GTS network if required, to generate a set of products. Data from both the primary satellite data (Meteosat-9) and the Rapid Scanning Satellite (Meteosat-8) are used.

In the case of Meteosat processing, the facility receives near-real-time level 1.5 data from the image processing system, which has performed a geometrical correction and removed imperfections in the images. A radiative transfer model is applied to compute expected radiances at the top of the atmosphere, as well as atmospheric correction tables. Scenes analysis provides information on the surface type in each cloud-free image pixel. This output is then presented to the various meteorological product applications as a classified pixel map and as segmented clustered scenes, and meteorological products are generated.

In addition to the EUMETSAT satellite data, input from sources external to EUMETSAT is required for the processing and verification of some products. Independent meteorological observations are used to verify a subset of the products, and verification results are stored along with the products themselves.

The Meteorological Product Extraction Facility (MPEF) provides the core functionality of the product extraction mission for an agreed set of meteorological products.

A sample of the products produced from MSG data by the MPEF is:

Atmospheric motion vectors derived from analysis of cloud motion, yielding information on winds in the atmosphere

Cloud analysis (including cloud cover, cloud top temperature and pressure)

Clear sky radiance

Precipitation index

Climate data set

High-resolution precipitation index

Global stability index, providing a few hours of warning for potentially strong convective storms

Fire monitoring

A product that came into prominence in April 2010 was the Volcanic Ash Detection product. The immense disruption to European air traffic caused by the eruption of the Eyjafjallajökull volcano in Iceland demonstrated the usefulness of the product and prompted efforts to enhance it.

The network of Satellite Application Facilities (SAFs) supplement the core set of centrally generated MSG products. The SAFs are located at the National Meteorological Services of EUMETSAT Member States. Utilizing specialist expertise from the Member States, SAFs form an integral part of the distributed EUMETSAT Application Ground Segment. Each SAF is a center of expertise along a specific theme in meteorological applications (Fig. 38.5).

Fig. 38.5 Network of EUMETSAT satellite application facilities

Each SAF is led by the National Meteorological Service (NMS) of a EUMETSAT Member State in association with a consortium of EUMETSAT Member States and Cooperating States, government bodies, and research institutes. The lead NMS is responsible for the management of each complete SAF project. The research, data, and services provided by the SAFs complement the standard meteorological products delivered by the MPEF in Darmstadt.

EUMETSAT supervises and coordinates the overall activities of the SAF network and the integration of the SAFs into the various operations within the EUMETSAT Application Ground Segment. It manages and coordinates interfaces - between the SAFs themselves and between SAFs and other EUMETSAT systems - overseeing the integration of SAFs into the overall ground segment infrastructure.

The SAFs help deliver a variety of benefits including:

Improvements to short-range forecasting of severe weather hazards

Support to the aviation, agriculture, construction, gas, water, and electricity industries

Better understanding of the causes and effects of pollution of the upper atmosphere and the depletion of ozone

Early warning of hazards

Better data for climate monitoring

Improved information for land use, ecology, disaster monitoring, and agricultural forecasting

Benefits for sea transport, fishing and offshore industries

Improved data for input to Numerical Weather Prediction and the availability of user software packages for operational applications

Improved software packages and near-real-time and offline products

There are currently eight SAFs providing products and services on an operational basis:

Support to Nowcasting and Very Short Range Forecasting SAF, hosted by AEMET, Spain. The main goal of the NWC SAF is to produce software packages, for local installation at the user's site, that support Nowcasting and Very Short Range Forecasting.

Ocean and Sea Ice SAF, hosted by Météo-France. The OSI SAF is an answer to requirements from the meteorological and oceanographic communities of EUMETSAT Member and Cooperating States for comprehensive information derived from meteorological satellites at the ocean-atmosphere interface. The OSI SAF offers a valuable complement to in situ data, based on continuously increasing temporal and geographical resolution products from coastal to global coverage.

Climate Monitoring SAF, hosted by Deutscher Wetterdienst, Germany. The CM SAF generates and archives high-quality datasets for specific climate application areas, through the exploitation of satellite measurements with state-of-the-art algorithms to derive information about the climate variables of the Earth system. It aims to provide data that can be further used to assess the current climate, e.g., for infrastructure planning, to assess the

climate variability and change including climate change detection and attribution, to support the development of climate models by validating long-range and short-term climate forecasts, to assess the impact of changing environment, and to provide evidence for policy actions.

Numerical Weather Prediction SAF, hosted by the United Kingdom Met Office. The NWP SAF exists to develop techniques for more effective use of satellite data in numerical weather prediction models. To achieve this, the NWP SAF updates, assesses, and prioritizes user requirements and develops the satellite data processing modules needed to meet those requirements. These include preprocessing, retrieval and assimilation modules, modules for monitoring, tuning, and quality control, and modules for validation of satellite products and of observation operators. It also monitors the quality of many satellite data streams and makes the results available on the web.

Land Surface Analysis SAF, hosted by Instituto Meteorologia, Portugal. The aim of the LSA SAF is to take full advantage of remotely sensed data relating to land, land-atmosphere interactions, and biosphere applications; a strong emphasis is put on developing and implementing algorithms that will allow an operational use of data from EUMETSAT satellites. The LSA SAF system generates, archives, and disseminates, on an operational basis, a set of parameters involved in the surface radiation budget, snow, vegetation cover, evapotranspiration, and fire-related products.

Ozone and Atmospheric Chemistry Monitoring SAF, hosted by the Finnish Meteorological Institute. The O3M SAF produces, archives, validates, and disseminates ozone and atmospheric chemistry products to support the services of the EUMETSAT Member States in weather forecasting as well as monitoring of ozone depletion, air quality, and surface UV radiation.

GRAS Meteorology SAF, hosted by the Danish Meteorological Institute. The GRAS SAF uses data from the GRAS (Global Navigation Satellite System Receiver for Atmospheric Sounding)

instrument on the polar-orbiting Metop satellite to generate high-quality GPS Radio Occultation (RO) datasets for Numerical Weather Prediction (NWP) applications and specific climate application areas.

Support to Operational Hydrology and Water Management SAF, hosted by USAM, Italy. The H-SAF generates high-quality data sets and products for operational hydrological applications from satellite data. Precipitation and soil moisture products are among its outputs.

Data Collection and Data Dissemination

The Meteosat Data Collection Service (DCS) enables environmental data to be collected via the Meteosat satellite from Data Collection Platforms (DCP), such as ground or air-based observing stations which can be located anywhere in the field of view of that satellite (where their line of sight to the satellite is at least 5° above the horizon). The DCS is particularly useful for the collection of data from remote and inhospitable locations where a DCP may provide the only possibility for data relay.

A particular example of the usefulness of the service is its role in the Indian Ocean Tsunami Warning System, whereby the DCS on EUMETSAT's Indian Ocean Data Coverage satellite contributes to relaying data from some 52 DCPs to the Pacific Tsunami Warning Center in Hawaii, which issues tsunami alerts.

The DCP data is processed at the EUMETSAT Control Centre and routed for further dissemination either via EUMETCast, the WMO Global Telecommunication System(GTS), the Internet, or by Direct Broadcast via the MSG satellite (at 0° longitude).

The data are transmitted at 100 bps for a Standard Rate platform and 1,200 bps for a High Rate platform.

DCPs operate in two main bands - international and regional:

International DCPs are characterized by the possibility that they can move from one field of view of one satellite to that of another. They have to operate in the "self-timed" mode, presently defined as a 1.5 min repeat cycle per transmission, including a safety margin of 15 s

at the beginning and the end. Eleven channels are available for this type of DCP. The bandwidth allocated for those International DCPs is 402.0355-402.0655 MHz.

Regional DCPs remain in the coverage area of one satellite. There are three types of DCP - Self-timed, Alert, and Hybrid (self-timed and alert). The "Alert mode" is to transmit short messages on a dedicated alert channel if one or more meteorological parameters exceed predefined thresholds. The bandwidth allocated for those Regional DCPs is 402.0685-402.4345 MHz, which can be used to support Standard Rate DCPs and High Rate DCPs. The bandwidth is divided into segments of 3 KHz for the MTP Standard Rate DCP, 2.25 KHz for the MSG High Rate DCP, and 1.5 KHz for the MSG Standard Rate DCP channels.

The EUMETSAT dissemination mission is responsible for the dissemination of data to the user community. Data to be disseminated include the processed image data, generated products, and meteorological data and products from other sources.

EUMETSAT's primary dissemination mechanism for the near real-time delivery of satellite data and products generated by the EUMETSAT Application Ground Segment is the EUMETCast system which also delivers a range of third-party products. Outside the EUMETCast footprint, they are disseminated by the World Meteorological Organization's Regional Meteorological Data Communication Network/Global Telecommunications System.

EUMETCast is a multiservice dissemination system which uses the services of a commercial satellite operator and telecommunications provider to distribute data files using Digital Video Broadcast (DVB) technology. One of the strengths of the system is the simplified user infrastructure and the resulting low cost for obtaining high-quality data. All available data can be received with a single reception station using off-the-shelf components.

The key features of EUMETCast are:

Secure delivery allows multicasts to be targeted to a specific user or group of users thus supporting any required data policy

Handling of any file format, allowing the dissemination of a broad range of products

Use of DVB turnarounds allows the easy extension of geographical coverage

One-stop-shop delivery mechanism allows users to receive many data streams via one reception station

There are currently over 3,000 EUMETCast user stations in operation.

EUMETCast is part of a global monitoring system. It is Europe's contribution to GEONETCast, the Group on Earth Observations' network of dissemination systems. Within the Global Earth Observation System of Systems (GEOSS), EUMETCast is a contributing system for global data dissemination and is also available for use by the European Global Monitoring for Environmental and Security (GMES) initiatives and other environmental data providers. EUMETCast is also a EUMETSAT contribution to the Integrated Global Data Dissemination Service (IGDDS), a component of the World Meteorological Organization (WMO) information service.

The Meteosat data disseminated via EUMETCast can be grouped into several classes, which are described here in order of priority for their dissemination:

The level 1.5 image and supporting data, as generated by the imaging mission; they constitute the highest priority data and are expected to be disseminated within 5 min of the reception of the raw image data on the ground.

Level 2.0 and 3.0 products (from the MPEF and SAFs), plus any supplementary data constitute the second priority data. The products to be disseminated comprise a predefined set of key products and a configurable set of additional products.

"Foreign" satellite data. This category comprises data from other meteorological satellite systems for distribution within the MSG dissemination. These may include data from other geostationary satellites and from polar-orbiting systems, with particular regard to data from satellites overlapping in their field of view with MSG.

GTS type data, including messages from DCPs and meteorological data service. The required retransmission responsivity of DCP messages will

depend upon the criticality type of the message.

The data are broadcast via EUMETCast to users operating a receiving station in the field of view of commercial communication satellites according to the coverage agreed by EUMETSAT Member States. Both HRIT and LRIT data are made available.

The direct dissemination of LRIT data via the MSG satellite (at 0° longitude) is also available for those users who are equipped with dedicated LRIT stations in the field of view of the MSG satellite (at 0° longitude).

High Rate Information Transmission (HRIT) and Low Rate Information Transmission (LRIT) are the CGMS standards agreed upon by satellite operators for the dissemination of digital data originating from geostationary satellites to users via direct broadcast. The distinction between the two standards, as their names suggest, is the data rate (bandwidth) necessary to convey the data content. LRIT data (mainly the meteorological products, a reduced set of images at low resolution) are typically disseminated at low bandwidth (typically 128 Kbps for direct dissemination via the MSG satellite at 0° longitude) while HRIT data (mainly the full earth and rapid scan images in full resolution) are typically disseminated at speeds up to 1 Mbps.

The EUMETSAT Data Centre

The EUMETSAT Data Centre stores all the organization's satellite data and derived products securely and helps users access the archived data. The Data Centre supports the data requirements of external users such as the National Meteorological Services, research organizations, universities, and commercial companies. It also supports internal users, like the Meteorology Division or Operations facilities which need the data for purposes such as research and reprocessing (www.eumetsat.int/home/main/satellites/MeteosatSecondGeneration).

The Data Center fulfills the following functions:

Acquisition and archiving of Level 1.0 and 1.5 Images

Acquisition and archiving of the MPEF Products

Generation and maintenance of catalogs covering the archived data sets plus the SAF catalog information

Provision of an online catalog query and product retrieval service (the EUMETSAT Portal) using a device known as the Product Navigator

User access to, and orders, of EUMETSAT data from the Data Centre are increasing continually. In 2009, over 1 PB was retrieved from the Data Centre in response to user ordering. The rate of retrieval of data clearly demonstrates that the Data Centre is more than a safe data store.

To cope with the growing access demands from users and new data streams from satellite missions planned in the future, the systems in the Data Centre are continually upgraded.

The Data Centre also hosts and operates the EUMETSAT Global Space-based Inter-Calibration System (GSCIS) collaboration server. GSCIS is an international collaborative effort to examine and harmonize data from operational weather satellites to improve climate monitoring and weather forecasting.

In addition to delivering real-time weather information over decades, Meteosat satellites have also been a source of observations relevant for climate and environmental monitoring with records dating back to 1981. These records now constitute a valuable dataset that is of great interest to climate scientists. These observations are used to analyze climate processes, climate variability, and climate change.

The first and second generations of Meteosat provide long series on many important Essential Climate Variables defined by the Global Climate Observing System (GCOS) which is under the aegis of WMO and other international bodies. This information is a great resource for climate studies, and the EUMETSAT Data Centre provides an efficient means of access to the data. The Earth's radiation budget is a major topic of study in relation to climate change and outputs derived from the Meteosat series, such as surface albedo, cloud properties and atmospheric humidity, are very relevant in this respect. MSG's Geostationary Earth Radiation Budget (GERB) mission provides additional valuable data on reflected solar radiation and thermal radiation emitted by the Earth and atmosphere

and represents another valuable contribution by EUMETSAT.

The existing first-generation Meteosat Visible and Infrared Imager (MVIRI) and MSG's SEVIRI and the future MTG's Flexible Combined Imager will extend the Meteosat data record to 50 years in 2032, longer than most other satellite records (Figs. 38.6-38.8).

Fig. 38.6 Image of Storm "Tuva," which developed over the North Atlantic following rapid cyclogenesis, from Meteosat-9, 31 January 2008

Fig. 38.7 Volcanic ash cloud (seen in reddish hues) emanating from the Eyjafjallajökull volcano in Iceland, detected from the rapid scanning service of Meteosat-8, 10 May 2010

Fig. 38.8 Dust storm over North Africa, from Meteosat-8, 21 February 2007

Meteorological Third Generation (MTG)

In June 2010, the Council of EUMETSAT approved the content of the Meteosat Third Generation (MTG) Program that will eventually supersede the MSG and give continuity of European meteorological geostationary satellite coverage until at least 2040.

As would be expected, the MTG will provide improved coverage in several ways. Breaking with tradition, the satellite in the series will have three-axis stabilization rather than spin stabilization. This of itself will ensure that the satellites instruments are constantly pointed to the Earth and enhanced images will result. Another major departure from previous practice is that the program will utilize two satellites in orbit together to provide full operational coverage. This arises from the decision to include a wider range of instruments in the mission and to split the operational load between two satellites. The additions include an atmospheric sounding capability, a lightning detection mission, and an ultraviolet sounder (Aminou et al. 2009).

In contrast to the current MSG Meteosat satellites, using a 2-t class spacecraft and an imager with 12 spectral channels, the planned Meteosat Third Generation imaging satellite will be a 3-t satellite with 16 nominal spectral channels. The second operational platform will carry out atmospheric sounding to observe the different layers within the atmosphere. The sounder will be one of the key innovations in the new program, allowing Meteosat satellites for the first time not just to image weather systems but to analyze the atmosphere layer by layer and to perform far more detailed chemical composition studies.

As before the program is being established through cooperation between EUMETSAT and the European Space Agency (ESA). A European consortium led by Thales Alenia Space of France will build the MTG spacecraft.

The satellite series will comprise four imaging and two sounding satellites. The imaging satellites, MTG-I, will fly the Flexible Combined Imager (FCI) and an imaging lightning detection instrument, the Lightning Imager (LI). The sounding satellites, MTG-S, will include an interferometer - the Infra-red

Sounder (IRS) with hyper-spectral resolution in the thermal spectral domain - and the high-resolution Ultraviolet Visible Near-infrared (UVN) spectrometer that will address the atmospheric chemistry requirements of the European Union's Global Monitoring for Environment and Security (GMES) program in respect of its Sentinel-4 mission.

The first spacecraft is likely to be ready for launch from 2017. At any time the operational requirement will be fulfilled by an in-orbit configuration of two parallel positioned satellites, the MTG-I (imager) and the MTG-S (sounder) platforms. The use of three-axis stabilization will enable more demanding user requirements on spatial resolution, repeat cycle, and signal-to-noise ratio to be met, and is a prerequisite to conduct soundings from geostationary orbit.

The first MTG-I and MTG-S prototypes are being developed by ESA as part of its MTG program. The EUMETSAT MTG program includes the procurement of the four recurrent satellites - three MTG-Is and one additional MTG-S - as well as six launches, the development of the ground segment and the operations of all satellites.

The EUMETSAT ground segment facilities for the MTG will be integrated into the existing multi-mission ground network infrastructure, which is common to first- and second-generation Meteosat and Metop and Jason missions.

Following on from its predecessors, MTG will also provide a Data Collection and Retransmission service to collect and relay environmental data from automated data collection platforms. It will also carry GEOSAR communications payload to relay distress signals to a central reception station in Europe that passes the signals on for quick organization of rescue activities. The geostationary relay allows a continuous monitoring of the Earth disk and immediate alerting.

The MTG data and products generated within the EUMETSAT Application Ground Segment will be made available in near real-time through future evolutions of current delivery mechanisms such as EUMETCast and the WMO Global Telecommunications System (GTS). For MTG, EUMETCast will be upgraded to cope with the greatly increased product throughput rates, without major new

technological needs for users and their reception stations. Some terrestrial-based dissemination mechanisms are also likely to be used to deliver special data sets to key users, but the broadcast capability provided by EUMETCast will remain the primary delivery mechanism. The EUMETSAT Data Centre will continue to archive all EUMETSAT including the MTG data and make them available through mechanisms such as the Product Navigator.

The EUMETSAT Application Ground Segment will be upgraded to accommodate the future processing requirements of MTG imager and sounder data. Both the Meteorological Product Extraction Facility (MPEF) and the Satellite Application Facility (SAF) Network will be enhanced to accommodate the processing of MTG data.

The Instruments

Flexible Combined Imager

The Flexible Combined Imager (FCI) on the MTG-I satellite will continue the very successful operation of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on Meteosat Second Generation (MSG). The satellite's three axes stabilized platform will be capable of providing additional channels with better spatial, temporal, and radiometric resolution compared to the current MSG satellites.

Requirements for the FCI have been formulated by regional and global Numerical Weather Prediction (NWP) and Nowcasting communities. These requirements are reflected in the design which allows for Full Disk Scan (FDS) with a basic repeat cycle of 10 min and a European Rapid Scan Service which covers of one-quarter of the full disk with a repeat cycle of 2.5 min. The FCI takes measurement in 16 channels of which 8 are placed in the solar spectral domain between 0.4 and 2.1 μm delivering data with a 1 km spatial resolution. The additional 8 channels are in the thermal spectral domain between 3.8 and 13.3 μm delivering data with a 2 km spatial resolution. In the rapid scanning mode, there will be two additional channels in the solar domain with a spatial resolution of 0.5 km and two in the thermal domain with a spatial resolution of 1 km.

The additional channels within the solar domain will surpass current aerosol retrievals, including volcanic ash, thereby providing an important contribution to future air quality

monitoring. The increased spatial resolution and range of channels will offer improved fire detection products and an increase in the quality of climate relevant products such as fire, radiative energy, and power, which are directly related to carbon dioxide production.

Lightning Imager

The Lightning Imager (LI) will offer improvements for Nowcasting by delivering information on total lightning (Inter Cloud - IC and Cloud to Ground - CG). The instrument will bring full hemispheric near real-time total lightning detection capabilities.

The benefit of the LI mission is that it will continuously and simultaneously observe total lightning over the hemisphere providing the information to the users with an extremely high timeliness.

It is expected that the Lightning service will combine complementary information on total lightning measured by the Lightning Imager and the surface-based networks measuring global distribution of cloud-to-ground lightning, as for instance measured by the surface-based Arrival Time Difference network (ATDnet), which together should strongly improve the quality of information essential for air flight safety. Each lightning stroke initiated by an electrical discharge in or below clouds causes radiation in the visible spectrum that will be detected by the Lightning Imager on board MTG-I. The LI will measure optical pulses initiated by lightning strokes emitting energy above a set threshold, at a wavelength of 777.4 nm with a spatial resolution of 10 km. The information delivered to the users will be time, position, and intensity of detected optical pulses.

Lightning observations will also benefit climate monitoring. One approach to assess the impact of climate change on thunderstorm activity is to globally monitor and long-term analyze the lightning characteristics, which would require a long-term stable and spatially homogeneous lightning observing system. Lightning is a major source of harmful nitrogen oxides (NOx) in the atmosphere which play a key role in the ozone conversion process and acid rain generation. A detailed knowledge of the global distribution of the total lightning (CG + IC) is a prerequisite for studying and monitoring the physical and chemical processes in the atmosphere regarding NOx.

Lightning observations from the geostationary orbit, delivered with spatially homogenous and well-characterized quality, are specifically suited to support these climate and atmospheric chemistry applications. The LI observations on MTG will complement the NOAA Geostationary Lightning Mapper (GLM) placed on the GOES-R and the GOES-S satellites and the information obtained from the ground detection networks.

Infrared Sounder

The new geostationary sounder service from the Infrared Sounder (IRS) on MTG-S is based upon requests from the NWP community to deliver spectral information and/or retrieved products as horizontal and vertical gradients of humidity and temperature. Making available 3-D information on humidity, temperature, and wind will support Nowcasting applications, particular in situations of water vapor convergence and convective instability, giving improved warnings on location and intensity of convective storms. The deduced information on atmospheric dynamics (e.g., Atmospheric Motion Vectors (AMVs) with a vertical resolution of about 2 km which surpasses the current products) will be invaluable to numerical models used in operational forecasting in the future. In particular, a breakthrough regarding better precipitation forecasts is expected by using this new information within these advanced models coupled with advanced data assimilation capabilities.

Another example of the expected benefits of the IRS instruments is information on ozone, carbon monoxide, and volcanic ash compositions within the atmosphere. The user community has already identified the crucial role of infrared instruments for future volcanic-ash monitoring. The improved MTG capabilities of the imagery mission will provide further details on the extent of the ash plume, whereas the capabilities of the MTG sounding mission will be essential for the derivation of quantitative products with additional information on the composition and density of the ash cloud.

Retrieving highly resolved vertical structures of humidity (~2 km resolution with 10% accuracy) and temperature (~1 km with 0.5-1.5° accuracy) by remote sensing techniques requires measurements within the water vapor and CO2 absorptions bands with extremely high spectral resolution and accuracy. The IRS is based on an imaging Fourier interferometer with a hyper-

spectral resolution of 0.625 cm−1 wave number and a spatial resolution of 4 km. The IRS will deliver over the Full Disk in a total of 1,720 channels in the infrared spectrum, with a basic repeat cycle of 60 min.

Ultraviolet Sounder

The Ultraviolet, Visible and Near-Infrared Sounding (UVN) instrument supports the Global Monitoring for Environment and Security (GMES) Sentinel 4 mission for geostationary chemistry applications. The primary objective of the Sentinel 4 mission is to support air quality monitoring and forecasting over Europe with a high revisit time (~1 h or better). The primary data products will be ozone, nitrogen dioxide, sulfur dioxide, formaldehyde, and aerosol optical depth.

The UVN will fly onboard the MTG-S satellites. Funding for the UVN is provided by the European Commission in cooperation with European Space Agency (ESA).

The UVN is a spectrometer taking measurements in the ultraviolet (UV: 305-400 nm), the visible (VIS: 400-500 nm), and the near infrared (NIR: 755-775 nm) spectra with a spatial resolution of better than 10 km. Its observations are restricted to Earth area coverage from 30° to 65° N in latitude and 30° W to 45° E in longitude. The observation repeat cycle period will be shorter than or equal to 1 h.

ESA is responsible for the definition of the Sentinel 4 mission and provision of the UVN Instrument, whereas EUMETSAT takes responsibility for the operational processing, delivery, and management of the instrument data.

Conclusion

Since EUMETSAT was established, its policy in relation to geostationary satellite programs has been to ensure long-term continuity to the users of its services based on proven technology and on effective exploitation of the satellite data. Building on the success of the original Meteosat series, initiated by the European Space Agency at the urging of the European national meteorological services, EUMETSAT's Meteosat Second Generation program provides a high-quality imaging facility over Europe, Africa, and the eastern Atlantic, as well as the Indian Ocean Data Coverage. It also supports the scientific and climate mission known as the Global Earth Radiation Budget (GERB).

Considerable effort is expended on extracting additional value from the data. The centralized product extraction facility at Darmstadt produces highly valuable sets of products based on analysis of the images. The innovative Satellite Application Facilities add immense value through their focus on specialized aspects of the data application.

With continuity beyond the MSG an imperative for EUMETSAT, the Meteosat Third Generation (MTG) has been initiated and will provide continuity of European geostationary meteorological satellite programs up to 2040.

Throughout its history, EUMETSAT has fostered international cooperation in satellite meteorology and has forged excellent relationships with other satellite providers in an effort to promote global coverage and to optimize the effectiveness of the investments in the satellite programs. Within Europe it works very closely with the European Space Agency and is taking an active role in the ambitious GMES (Global Monitoring for the Environment and Security) plan of the European Union. It has also addressed the needs of the developing world through various initiatives, such as the Preparation for the Use of MSG in Africa (PUMA) and AMESD (African Monitoring of the Environment for Sustainable Development).

The general direction that future developments in relation to EUMETSAT geostationary meteorological programs will take is to a large extent already evident in the agreed content of the MTG program. New satellite technology accompanied by enhancement of existing design solutions (e.g., three-axis stabilization rather than the spin stabilization) will enable a wider range of instruments of greater sophistication and higher spectral resolution at the level of affordability comparable to the past programs.

Some other factors which dictate the trends affecting EUMETSAT programs are the need to utilize technology and instruments that are well proven rather than experimental because of the operational dependence on them. Another factor, evident, for example, in the cooperation between EUMETSAT and the EU GMES Program on MTG (and the next generation of the EUMETSAT polar-orbiting systems), is the broadening of meteorological satellite programs to include a wider range of Earth observation. Within meteorology, the mathematical models use an increasingly diverse range of data sources including those

derived from ocean and land observation. Such cross-over usage of data is also likely to become evident in other disciplines. This kind of development is likely to become a stronger feature as more and more operational systems become reliant on space-based observation. In Europe, this trend may be particularly strong as the full GMES program is rolled out.

The benefits of international cooperation are likely to become even more evident. The close cooperation between EUMETSAT and NOAA is an outstanding example of this at present, as demonstrated by the collaboration on geostationary and polar-orbiting programs. The growing role of other operators such as China, Japan, India, and South Korea are likely to lead to an increased level of global coverage and to closer collaborative links. 1

Cross-References

International Meteorological Satellite Systems

Notes

1. An agreement is in place between EUMETSAT and NOAA on what is called the Initial Joint Polar-orbiting operational Satellite (IJPS) System. This program includes two series of independent but fully coordinated EUMETSAT and NOAA satellites and the exchange of instruments and global data, cooperation in algorithm development, and near real-time direct broadcasting. Under the terms of the IJPS agreement, NOAA provides NOAA-18 and NOAA-19 satellites for flight in the afternoon (PM) orbit and EUMETSAT provides MetOp-A and MetOp-B satellites for flight in the mid-morning orbit (AM). The IJPS Agreement is complemented by a Joint Transition Activity Agreement, covering the Metop-C satellite on the European side and the NOAA (NPOESS) Preparatory Project (NPP) satellite, launched on 28 October 2012, and JPSS-1 satellite on the U.S. side. These satellites carry a common core of instruments (see Chap. 26, "Introduction and History of Space Remote Sensing"). With NPP, NOAA will continue to share complementary data and information on weather and climate from low earth orbit with EUMETSAT to maximize each agency's investments in space and EUMETSAT will disseminate NPP data in Europe. NOAA and EUMETSAT are also discussing the continuation of their cooperation, under a Joint Polar System Agreement, which will cover the upcoming NOAA JPSS-2 and follow-on satellites and the EUMETSAT EPS SG satellites. For further information on EUMETSAT please visit www.eumetsat.int

References

D. Aminou et al., Meteosat third generation (MTG) status of space segment definition, in

2009 EUMETSAT Meteorological Satellite Conference, Oslo, 2009, http://www.eumetsat.int/Home/Main/AboutEUMETSAT/Publications/ConferenceandWorkshopProceedings/

ESA MSG Website, www.esa.int/esaMI/MSG

EUMETSAT Website, www.eumetsat.int/home/main/satellites/MeteosatSecondGeneration

J. Schmetz et al., An introduction to Meteosat second generation (MSG). Bull. Am. Meteor. Soc. 83, 977-992 (2002)

J. Schmid, The SEVIRI instrument, in 2000 EUMETSAT Meteorological Satellite Conference, Bologna, 2000, http://www.eumetsat.int/Home/Main/AboutEUMETSAT/Publications/ConferenceandWorkshopProceedings