Learning to Predict Climate Variations Associated with El Nino and the Southern Oscillation Accomplishments and Legacies of the TOGA Program (1996) / Chapter Skim
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2. GROWTH OF THE TOGA PROGRAM
2. GROWTH OF THE TOGA PROGRAM
Pages 12-21
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From page 12... ...
He also suggested that the combined ENSO phenomenon resulted from dynamics that coupled the atmosphere and the upper ocean in the region of the equatorial Pacific. Coherent research efforts on ENSO developed during the 1970s, motivated in part by recognition of disruptive effects in the Americas from climate variations thought to be associated with ENSO.
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From page 13... ...
He reasoned that the resulting pattern of sea surface temperature reinforces the strength of the trade winds by favoring large-scale atmospheric cooling, descent, and cloud-free conditions over the equatorial eastern Pacific, accompanied by large-scale ascent with relatively large amounts of precipitation, convective clouds, and atmospheric heating over the central and western equatorial Pacific. In the equatorial region, the east-west atmospheric heating differences would be expected to drive an east-west atmospheric overturning, which Bjerknes named the Walker circulation.
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From page 14... ...
The hypothesis emphasized the importance of sea surface temperature in producing the observed atmospheric anomalies during ENSO. However, many gaps in understanding remained, such as the mechanisms that control the initiation, development, termination, and irregular occurrence of warm events.
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From page 15... ...
On the basis of empirical evidence, Wyrtki hypothesized that the warm equatorial surface waters that developed at the western side of the basin during the period of abnormally strong trade winds would "surge" eastward, probably in the form of an equatorial Kelvin wave, depressing the thermocline as it passed. This would cause an abrupt rise in sea level and an increase in sea surface temperature through a reduction in the effects of upwelling on the eastern side of the basin.
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From page 16... ...
The dynamical processes by which equatorial waves are reflected at boundaries on the eastern and western sides of the equatorial oceans were investigated (Cane and Moore 1981, Anderson and Rowlands 1976, Cane and Sarachik 1977, Moore and Philander 1977, Clarke 1983, Cane and Gent 1984~. A simulation of the response of a bounded equatorial ocean to a uniform meridional wind forcing demonstrated that cross-equatorial flow over the eastern equatorial Pacific Ocean might also play an important role in determining the structure and variability of the "cold tongue" of sea surface temperature extending offthe South American coastline (Philander and Pacanowski 1981b)
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From page 17... ...
1985~. Although a definitive explanation for the mechanism causing anomalous patterns of atmospheric planetary waves was lacking, theoretical studies conducted during this period indicated that the energy of planetary-scale waves generated by a regional process in the equatorial zone was able to propagate to remote regions of the global atmosphere within a few days under certain conditions.
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From page 18... ...
The study group also recognized that such an investigation might be feasible because the seasonal-to-interannual oceanic variability appeared to be confined primarily to the upper ocean of the tropics, while the extratropical ocean circulation on these time scales appeared to be relatively insensitive to remote atmospheric influences. This recognition narrowed the scope of the investigation and provided a scientific basis for setting priorities on the observational and modeling activities.
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From page 19... ...
It would not be possible to make fundamental progress by consideration of either the atmosphere or the oceans alone. Observational systems and models were needed to describe the system encompassing the tropical oceans and the global atmosphere, a system in which the processes determining sea surface temperature, atmospheric heating, surface wind stress, and ocean circulation were related to each other in feedback loops (see Figure 1~.
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From page 20... ...
While the formal objectives of the international TOGA Program did not mention ENSO specifically, it had been known that the ENSO phenomenon dominated the interannual variability of sea surface temperatures in the tropical Pacific (Weare et al.
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From page 21... ...
The drafters of the original science plan (NRC 1983) could not determine the optimal location for the process experimenters)
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