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In addition, the NWP SAF hosted by the UK Met Office can
exploit Metop’s data to generate supporting data, software pack-
ages, validation products and other services for use in NWP,
climate studies and atmospheric research.
Scatterometer wind measurements are of great importance to
weather forecasting and climate monitoring, as demonstrated
through various research missions over the past decade. Data
from the advanced scatterometer (ASCAT) is further processed
by the Ocean and Sea Ice (OSI) SAF, led by Météo-France, to
provide global ocean surface wind vectors that are necessary
for the definition of atmospheric circulation on small scales and
in the tropics. The main application of this is the assimilation
of wind measurements into NWP models. Scatterometer
measurements can also be used for monitoring sea ice, snow
cover or land surface parameters such as soil moisture.
A combination of the advanced TIROS Operational Vertical
Sounder (ATOVS) suite and the Advanced Very High-resolu-
tion Radiometer (AVHRR), currently flown on NOAA
satellites, are also operated on board Metop. ATOVS/AVHRR
covers the visible, infrared and microwave spectral regions,
making this combination useful for a variety of applications
such as cloud and precipitation monitoring, determination of
surface properties or humidity profiles, all of which play a key
role in NWP.
Monitoring climate and the environment
The likely impact of extreme weather events, climate change
and human activities on the environment can be predicted
using computer models that use satellite data collected
continuously over many decades. These predictions reveal
pressing environmental issues and enable them to be
addressed more effectively, ensuring that national policies
and activities are consistent with the goal of sustainable devel-
opment.
All the instruments on board Metop contribute to global
climate monitoring models and applications, helping scientists
to understand the complex interactions between the various
factors that influence the Earth’s climate system.
In particular, IASI’s ability to detect and accurately measure
the levels and circulation patterns of gasses known to influ-
ence the climate, such as carbon dioxide (CO
2
), will herald a
breakthrough in the global monitoring of the climate. The data
collected by IASI will feed into models to show for the first
time the variable global distribution of CO
2
as a function of
seasons and circulation anomalies, such as the southern oscil-
lation (also known as El Niño) and the North Atlantic
oscillation.
The depletion of the ozone layer is currently of particular
environmental concern, and is especially noticeable over the
Arctic and Antarctic regions. The resulting increased levels of
ultraviolet radiation have harmful effects on agriculture, forests
and water ecosystems – and people.
The Global Ozone Monitoring Experiment (GOME-2) will
measure ozone profiles, total columns of ozone and other
atmospheric constituents like nitrogen dioxide and sulphur
dioxide. The trace gases observed are related not only to the
depletion of ozone in the stratosphere, but also to sources such
as volcanic eruptions and biomass burning. Long-term moni-
toring of the trace gases will provide more insight into the
impact of man-made sources of pollution on the environment
(including air quality) and the climate, on both regional and
global scales.
by the new generation of Meteosat satellites is vital to ensure daily
life and business. For scientists, the data gathered by satellites are
also invaluable for climate monitoring. However, the geostation-
ary position of the Meteosat satellites implies that in order to
deliver the highly detailed observations of atmospheric conditions
that meteorologists and climatologists require, a low earth orbit
system was needed to complement the geostationary service.
In response to this need, the councils of EUMETSAT and the
European Space Agency (ESA) agreed plans to design, develop,
launch and operate a polar satellite system for Europe. The
EUMETSAT Polar System (EPS) programme was then approved
in 1999.
In 1998 EUMETSAT and the National Oceanic and
Atmospheric Administration (NOAA) began collaborating on
the Initial Joint Polar System (IJPS), comprising two polar-
orbiting satellite systems and their respective ground segments.
A further agreement in 2003, the Joint Transition Activities
agreement, saw the two organizations working to provide an
operational polar-orbiting service until at least 2019.
Metop and Numerical Weather Prediction
Numerical Weather Prediction (NWP) is the basis of all modern
global and regional weather forecasting, and EUMETSAT’s Metop
satellites will make a substantial contribution in this area.
Metop serves the operational requirements of the meteoro-
logical services and other users around the world, including
the WMO and EUMETSAT’s Member and Cooperating States.
The first satellite of the EPS system was launched in 2006 from
Baikonur, Kazakhstan. Its altitude of 837km makes it approx-
imately 42 times closer to the Earth than a geostationary
satellite, and it can therefore observe smaller areas in consid-
erably finer detail. Data gathered by Metop will revolutionise
the way weather, climate and environment are observed, and
will significantly improve operational meteorology.
Data generated by instruments onboard Metop can be assim-
ilated directly into NWP models in order to compute forecasts
ranging from a few hours to ten days ahead. Measurements from
infrared and microwave radiometers and sounders on board
Metop provide NWP models with global information on the
temperature and humidity of the atmosphere with a high verti-
cal resolution. The Infrared Atmospheric Sounding
Interferometer (IASI), for example, provides important data
including highly detailed global measurements of atmospheric
temperature and water vapour, making it possible to ascertain
temperature and humidity profiles with a vertical resolution of
1km, accurate to 1 degree Celsius and ten per cent respectively,
at a horizontal sampling of 20km.
Metop’s Global Navigation Satellite System Receiver for
Atmospheric Sounding (GRAS) instrument presents a new
method for using satellite observations in NWP models for
weather forecasting and climate monitoring. Using radio
signals continually broadcast by the GPS satellites of the Global
Navigation Satellite System orbiting the Earth, GRAS measures
the time delay of the refracted GPS radio signals as the ray
signal path skirts the Earth’s atmosphere on its way from the
transmitting GPS satellite to the GRAS receiver on Metop. This
delay is then processed to obtain vertical profiles of atmos-
pheric parameters, such as temperature and water vapour in
the stratosphere and troposphere.
The data collected by GRAS will be further processed into
sounding products by the GRAS satellite application facility
(SAF), which is hosted by the Danish Meteorological Institute.