Meteorology, Meteorological, History

An IGO
monit-
oring
weather and
climate
change

HISTORY OF EUMETSAT, p14.

HISTORY OF EUMETSAT, p12.

p13

The first need is met in large part by the traditional methods of science - an aspiration (often met) to open publication, uncensored critiques and the free exchange of data.

How do meteorologists meet the second need? Twice daily, weather balloons are released all over the world. Instruments on ships and aircraft collect data. A global network of land-based weather stations makes observations. The data collected are relayed with the regularity of clockwork via a global telecommunication system to the world's meteorological services. This quiet, efficient collection and sharing of data globally for a common purpose is one of the more impressive and unknown achievements of the modern world, but it is not enough. Two thirds of the globe is covered by ocean. Large tracts of the Earth's surface are too remote from centres of population to make regular observations possible. That is why the advent of satellites in 1957 led some meteorologists to believe that spacecraft would collect the comprehensive, detailed data they needed.

From the beginning, the imagery was stunning and showed in practice the weather fronts and systems that meteorologists had deduced in theory. Unfortunately, the satellites did not immediately usher in the expected golden age of data. Although the imagery gave meteorologists knowledge of how systems were developing, and thus served as a reality check for the interpretation of predictions made using conventionally collected data, it was not until the late 1970s that quantitative meteorological data began to win more widespread acceptance as a potential source of data for mathematical models (Numerical Weather Prediction). But by the time EUMETSAT came into existence in 1986, it was clear, according to the Organisation's first Director, John Morgan, that if mathematical models were to fulfil their promise they needed the kind of global data sets that only a satellite can provide.

So for the first 15 years of its life, the Organisation has worked to develop satellite and ground systems that will provide the most comprehensive data possible for mathematical models, as well as observations that help meteorologists interpret the predictions of the models. This job is perhaps one of the hardest scientific, technical and political tasks facing an intergovernmental organisation.

At a technical level, two of the most profound difficulties are the nature of the observations that satellites make and the fact that the satellites and instruments making the observations must be very reliable because it is not possible to bring a spacecraft in for servicing once it is in orbit.The satellites concerned occupy two different types of orbit: geostationary and polar. Geostationary satellites are in orbit at an altitude of nearly 36,000 kilometres. At that altitude, it takes a satellite 24 hours to complete its orbit. If the orbit is also coplanar with the equator, the satellite will appear to remain stationary with respect to the point immediately below. This happy accident of physics means that satellites in geostationary orbit are ideally placed to observe one region of the Earth constantly. EUMETSAT operates two satellites and one back-up in geostationary orbit. The primary Meteosat is at 00 Longitude and keeps a constant watch on Europe, Africa and neighbouring oceans. It is backed-up by a "hot stand-by"

SEE ALSO| |

1. Meteorologists shed political shackles, a review of Declan Murphy's history of the first 25 years of EUMETSAT (2011), by Helen Gavaghan.

2. An interview in 2010 with Dr Tillman Mohr, a special advisor to the secretary general of the World Meteorological Organisation, in Science, People & Politics.

eChapter| |TOP

Contents

Preface

Foreword

Introduction

Ch.1

Ch.2

Ch.3

Ch.4

Ch.5

Ch.6

Ch.7

Ch.8

The History of EUMETSAT is available in English and French from EUMETSAT©.
First printed 2001. ISBN 92-9110-040-4

Eumetsat meteorology meteorological artificial satellites
European Space Agency weather climate policy politics history