Climate Fluctuations of Tropical Coupled Systems—The Role of Ocean Dynamics

• Published in: Journal of climate 2006-10, Vol.19 (20), p.5122-5174
• Main Authors: Chang, P., Yamagata, T., Schopf, P., Behera, S. K., Carton, J., Kessler, W. S., Meyers, G., Qu, T., Schott, F., Shetye, S., Xie, S.-P.
• Format: Article
• Language: English
• Subjects: Atmosphere; Atmospheric circulation; Atmospheric models; Budgets; Climate; Climate change; Climate models; Climate prediction; Climate studies; Climate variability; Climate variations; Climatic conditions; Dipoles; Dynamics; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; Fluctuations; Frequency dependence; Frequency modulation; Ocean basins; Ocean circulation; Ocean dynamics; Ocean models; Ocean-atmosphere interaction; Ocean-atmosphere system; Oceanic climates; Oceanographic research; Oceans; Predictability; Predictions; Sea surface; Sea surface temperature; Sea surface temperature variations; Southern Oscillation; Studies; Surface temperature; Surface water; Temperature variations; Thermocline; Thermoclines; Thermohaline circulation; Tropical atmosphere; Tropical circulation; Tropical climates; Tropical regions; Variability; Ventilation
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/JCLI3903.1

The tropical oceans have long been recognized as the most important region for large-scale ocean–atmosphere interactions, giving rise to coupled climate variations on several time scales. During the Tropical Ocean Global Atmosphere (TOGA) decade, the focus of much tropical ocean research was on understanding El Niño–related processes and on development of tropical ocean models capable of simulating and predicting El Niño. These studies led to an appreciation of the vital role the ocean plays in providing the memory for predicting El Niño and thus making seasonal climate prediction feasible. With the end of TOGA and the beginning of Climate Variability and Prediction (CLIVAR), the scope of climate variability and predictability studies has expanded from the tropical Pacific and ENSO-centric basis to the global domain. In this paper the progress that has been made in tropical ocean climate studies during the early years of CLIVAR is discussed. The discussion is divided geographically into three tropical ocean basins with an emphasis on the dynamical processes that are most relevant to the coupling between the atmosphere and oceans. For the tropical Pacific, the continuing effort to improve understanding of large- and small-scale dynamics for the purpose of extending the skill of ENSO prediction is assessed. This paper then goes beyond the time and space scales of El Niño and discusses recent research activities on the fundamental issue of the processes maintaining the tropical thermocline. This includes the study of subtropical cells (STCs) and ventilated thermocline processes, which are potentially important to the understanding of the low-frequency modulation of El Niño. For the tropical Atlantic, the dominant oceanic processes that interact with regional atmospheric feedbacks are examined as well as the remote influence from both the Pacific El Niño and extratropical climate fluctuations giving rise to multiple patterns of variability distinguished by season and location. The potential impact of Atlantic thermohaline circulation on tropical Atlantic variability (TAV) is also discussed. For the tropical Indian Ocean, local and remote mechanisms governing low-frequency sea surface temperature variations are examined. After reviewing the recent rapid progress in the understanding of coupled dynamics in the region, this study focuses on the active role of ocean dynamics in a seasonally locked east–west internal mode of variability, known as the Indian Ocean d