The GARP tropical experiment begins

The time was not ripe to launch a truly global experiment immediately. Observations from tropical regions were sparse and the dynamics of tropical disturbances and their role in the exchange of heat and water vapour within the atmosphere as well as between the atmosphere and the oceans was poorly understood. Not least, there was a need to find out how the small-scale convective systems are organised and contribute to the formation of larger-scale disturbances. It was not yet realistic to aim for a dense network of observations all around the world in a global experiment as was foreseen as the ultimate project. But it was felt that sufficient knowledge and understanding might be obtained over a few months from a dense network of observations covering one or a few limited areas. This might then be useful in the interpretation of observations from a sparser network of global data.

Therefore, at an international meeting called by the WMO in 1970, the JOC proposed that a tropical subprogramme should be the first project to be implemented, while the planning for a global experiment continued. This was indeed ambitious in light of the advanced set of observations that was aimed for in the tropical experiment: these required two geo-stationary satellites, a dozen well-instrumented aircraft, two of which had to be long-range jets, and some 20 ships to establish a network of ocean stations (JOC, 1972).

After a year's delay, the experiment, which was called the GARP Atlantic Tropical Experiment (GATE) finally began in 1974. It had originally been intended to conduct the experiment in the tropical Pacific Ocean but this was vetoed by the US military authorities. In retrospect one might wonder what would have been discovered about the El Nino phenomenon in the Pacific in the 1970s, if the original plans had been realised. It would be another 15 years before the tropical Pacific was similarly well observed.

3.1.3 The GATE as a starting point for global climate studies

The prime task for the JOC was to improve the observational network in order to provide data for testing the models that were being developed for weather forecasting. This was, however, also to be an important prerequisite for the development of climate models, but it did not seem meaningful to address the climate issue in all its complexities to begin with. In addition to GATE there were also several other subprogrammes that were very important for the fulfilment of the general GARP objectives, i.e. studies of 'air-surface interaction' and 'atmospheric radiation.'

The JOC began the planning of a First Global GARP Experiment, FGGE, at the very beginning of its existence with the aim of launching an experiment in 1972. A meeting of representatives from participating countries did not, however, take place until 1970, on which occasion they were asked to support the planning so far and to commit national resources for the common purpose, but at that time the GATE necessarily, and rightly so, was given priority.

It is, however, noteworthy that by then almost 10 years had gone by since Charney had outlined in Bergen the new possibilities that computers and satellites might provide. Much had, of course, changed during these years, but the aims remained high (JOC, 1971, 1972). The plans for FGGE included the use of four geo-stationary satellites for observations of the tropics and the subtropics, and two polar orbiting satellites to achieve global coverage. In addition, the poor coverage of surface data in the southern oceans was to be improved by free-floating buoys communicating with the world data centres via satellites. Another novel observational platform was high-flying drifting balloons which provided the means to compare satellite observations and in situ measurements, with focus on the Southern Hemisphere.

However, it was seven more years before the elaborate plans were realised: the experiment took place between 1 November 1978 and 30 June 1980. This is not the place to describe these efforts in detail, but FGGE greatly advanced our knowledge.8 In retrospect it is interesting but also sad to note that there has not been such a complete programme of atmospheric observations since then. Today, early in the twenty-first century, we are trying hard to prevent an ongoing deterioration of the surface-based observational system. Paradoxically, there is at the same time an extraordinary interest in defence against natural disasters and the threat of a human-induced climate change due to the emission of greenhouse gases is constantly increasing. This indeed signifies a remarkable change in the politics regarding scientific and technological development for the pursuit of environmental studies during the last few decades. The scientists leading the GARP efforts were lucky in that the necessity of understanding the fundamental scientific issues in order to be able to develop new methods for weather forecasting was obvious and recognised. The reduced resources in later years are, however, to a considerable degree due to the increasingly complex political issues that the world only gradually became aware of in the 1990s.

Continue reading here: Concern for the environment reaches the political agenda

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