Geoscience Reference
In-Depth Information
levels has been available for more than 30 years. In northern regions, which have a
latitude of 15°S, the climatological stations have only been in place since the end of
the 1970s, or more recently in some cases. In these northern regions, the stations
were installed at the beginning of colonial farming programs: the oldest stations in
the northern regions are Vera and Porto dos Gauchos, which were installed in 1973,
and Alta Floresta, which was installed in 1978. Just as Marchand [MAR 85] had
noticed for Ireland, this spatial distribution summarizes the history of the
development of Mato Grosso, and also shows the shift of the main area of interest
from the southern part of the state to the north. At the moment, the installation of
new stations depends on the movement of the population, which does not follow a
precise logic.
In France, the Météo-France network (whose headquarters are located in
Toulouse) relies on departmental associations: the departmental centers for
meteorology. In France there are just over 3,000 measurement sites, which are
spread out over the country (one site for every 180 km
2
) that produce the same
quality of data. Numerous spatial gaps exist, especially in mountainous areas (in
high-altitude areas or on the north-facing sides of mountains). To make up for these
gaps, irrespective of the region being studied, satellites are able to produce a regular
mesh spatial interpolation map. Contrary to the data collected at ground level, which
is often made up of a mixture of different variables, satellite information is coherent
and homogenous. The frequency of their observations is much greater than the
frequency of observations produced by official measurement sites. This information
provides us with a better understanding as to why satellite observation techniques
have adopted a somewhat operational character.
3.2.2.
The progressive development of operational techniques
The observation of the Earth's atmosphere has been a priority ever since the
introduction of satellite remote sensing. From the 1960s right up until the end of the
1980s the majority of satellites were used for military purposes. There are, on
average, 50 satellite launches per year and approximately 80% of them are used for
strategic reasons. Only 2-4 of such launches were used for civil observations
(mainly by using the Landsat and SPOT programs). Over the past three decades
there has been a significant number of satellite launches for meteorological
purposes; on average, five to six launches per year. Since 1991 and the end of the
Soviet and communist regimes in Eastern Europe, the number of meteorological and
civil observation satellites launched has overtaken the number of military satellites
launched. The number of military launches has been halved and there is now a
wider range of countries that launch the satellites. Pioneering countries, such as the
USA and Russia, are facing competition from countries such as Europe, Japan, and
the emerging countries of China, Brazil, India, and Israel, which have their own
space programs [VER 92]. Looking back at the history of satellite observation over
the past 45 years it is possible to divide the 45 years into four successive phases,
with each phase lasting for a period of 12 years.
