Geoscience Reference
In-Depth Information
Archives for the oceans began in 1854 when the major maritime nations began a
regular program of recording atmospheric and oceanic data. Such data were
recorded mostly in the popular sea lanes, and for large oceanic areas only limited
data were available.
As shown in Table
4.1
, today's climatologists have available a number of
outstanding data sources. All are readily accessible, many from the World Wide
Web. However, extreme caution must be used when analyzing the data, for
without a good knowledge of statistical techniques, many fundamental errors
can be made. This is particularly true when correlations are completed, for some
conclusions may be reached when a statistical relation appears between para-
meters with no identified scientific physical relationship.
Together with satellite imagery, perhaps the most significant development for
climatology has been the availability of rapid computations through computer
analysis. Many research papers that are published in the current literature use
reanalysis, the subject of the essay that follows.
4.3 ESSAY: Reanalysis
Brian Giles, University of Birmingham
Reanalysis is the most recent in a long line of techniques used to improve our
understanding of the climatology of planet Earth. Climatology is variously
described as the synthesis of average and extreme weather conditions (Durst
1951
), or the long-term aspects of meteorological processes (Lamb
1972
). As
Sorre (
1934
) put it climate is ''l'ensemble des ph´nom`nes m´t´orologiques
qui caract´rise la condition moyenne de l'atmosphe`reenchaquelieudela
terre.''
1
But each of these phrases requires refinement, not least in the way in
which the meteorological elements are measured. Landsberg (
1987
)described
it as ''a statistical collective,'' which means that the data used must be compa-
tible. After the first scientific weather instruments were invented in the seven-
teenth century (Chapter
3
in Khrgian
1970
) scientists in Europe exchanged
weather data, began to produce means and extremes, ensured their instruments
were compatible with each other, and rationalized their units. This was helped
during the nineteenth century by the development of national meteorological
institutes and services (Chapters
8
and
9
in Khrgian
1970
).
4.3.1 The background
In the twentieth century, four periods can be distinguished: the first 40 years
were the ''surface'' period - the state of the art of climatology at the
1
The ensemble of meteorological phenomena that characterize the average condition of the atmo-
sphere in each part of the Earth.
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