GOALS (Global Ocean-Atmosphere-Land System) for Predicting Seasonal-to-Interannual Climate A Program of Observation, Modeling, and Analysis (1994) / Chapter Skim
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1 INTRODUCTION
1 INTRODUCTION
Pages 3-12
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From page 3... ...
The change of seasons associated with the annual cycle is also perhaps the most predictable variation. In the middle latitudes, where the United States is located, this cycle is often described in terms of warm (or hot)
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. It explains that GOALS would expand upon the original TOGA focus by laying a broader foundation for dynamical prediction of global climate variability at seasonal-to-interannual time scales.
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In general terms, when pressure is high in the Pacific Ocean, it tends to be low in the Indian Ocean from Africa to Australia. We now know that Walker was observing the two phases that manifest the Southern Oscillation in the tropical Pacific El Nino and La Nina, or the warm phase and the cold phase, respectively.
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Locally it would bring heavy rains, which in turn brought an abundance of vegetation including crops, grass for grazing, and other products that seemed like gifts. It is now known that the anomalous surface-water temperatures off the South American coast during the E1 Nino and La Nina phenomena often extend thousands of kilometers offshore and are but one aspect of anomalous oceanic and atmospheric conditions throughout the tropical Pacific.
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Bjerknes viewed the shifts in rainfall patterns as forcing for the global anomaly pattern embodied in the Southern Oscillation (Bjerknes, 1966, 1969~. During the 1970si, empirical studies of the tropical upper ocean led to the hypothesis that the evolution of equatorial SST anomalies during the onset of a warm episode in the eastern Pacific could be explained by a coupling between the decreasing southeasterly tradew~ds and equatorial wave activity in the tropical upper ocean through the mechanical forcing by surface wind stress (Wyrtki, 1975~.
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were shown to be simulated reasonably by simple ocean models, when forced with the climatologically varying winds, determined from data collected over long periods from volunteer observing ships in the tropics and then subjectively analyzed into wind fields (Busalacchi and O'Brien, 1981; Busalacchi et al., 1983~. This success indicated that it is only the largest-scale aspects of the wind fields that are responsible for the observed large-scale thermocline variations.
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However, it should be noted that essentially all the work and progress have been in and over the tropical Pacific Ocean. By focusing on understanding and predicting ENSO, the largest identified signal of interseasonal and interannual variability in the circulation of the atmosphere and the tropical Pacific upper ocean, the TOGA program was able to define clearly its observational requirements and to motivate process studies.
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This process study is examining the mutual interactions between the ocean and atmospheric convective activity over the ocean and is addressing the coupled modeling of these interactions. An operational Pacific Ocean modeling and data assimilation effort designed to synthesize irregularly taken ocean data into dynamically consistent fields of information has been started and continues to be run at the Climate Analysis Center of the National Weather Service (Derber and Rosati, 1989; Leetmaa and li, 1989; Miyakoda et al., 1990~.
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From page 11... ...
Not the least of the accomplishments of TOCA has been the cooperation of two diverse research communities, the ~eteoroIogical and We oceanographic communities, in pursuing common TOCA goals
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