Narrowing theuncertainty 223in the average radiation quantities – that is proving highly demanding.
Associated with the better measurements of clouds is the need for all
aspects of the hydrological (water) cycle to be better observed.
There is also inadequate monitoring at present of the major oceans of
the world, which cover a large fraction of the Earth’s surface. However,
this is beginning to be remedied with the introduction of new methods
of observing the ocean surface from space vehicles (see box below)
and new means of observing the interior of the ocean. But not only are
better physical measurements required: to be able to predict the detailed
increases of greenhouse gases in the atmosphere, the problems of the
carbon cycle must be unravelled; for this, much more comprehensive
measurements of the biosphere in the ocean as well as that on land are
needed.
Stimulated by internationally organised observing programmes such
as the GCOS, space agenciesaround the world have been very active
in the development of new instruments and the deployment of advanced
space platforms that are beginning to provide many new observations
relevant to the problems of climate change (seebox below).
Space observations of the climatesystem
For forecasting the weather round the world – for airlines, for shipping,
for many other applications and for the public – meteorologists rely
extensively on observations from satellites. Under international agree-
ments, five geostationary satellites are spaced around the equator for
weather observation; moving pictures from them have become familiar
to us on our television screens. Information from polar orbiting satel-
lites is also available to the weather services of the world to provide input
into computer models of the weather and to assist in forecasting (see for
instanceFigure 5.4).
These weather observations provide a basic input to climate models.
But for climate prediction and research, comprehensive observations
from other components of the climate system, the oceans, ice and land
surface are required. ENVISAT, a satellite launched by the European
Space Agency in 2002, is an example of the most recent generation of
large satellites in which the latest techniques aredirected to observing the
Earth. The instruments are directed at the measurement of atmospheric
temperature and composition (MIPAS, SCIAMACHY and GOMOS),
sea surface temperature and topography, the latter for ocean current
information (AATSR and RA-2), information about ocean biology and
land surface vegetation (MERIS) and sea-ice coverage and ice-sheet
topography (ASAR and RA-2).