A modeling study of teleconnections and their tropical sources

• Main Authors: Manola, Iris, Μανωλά, Ίρις
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Institutes outside Greece 2014
• Subjects: Φυσική της ατμόσφαιρας; Ατμοσφαιρικές τηλεσυνδέσεις; κύματα Rossby; Παγκόσμια και περιοχικά κλιματικά μοντέλα; Κύμανση βορείου ατλαντικού; Atmospheric physics; Atmospheric teleconnections; Rossby waves; Global and regional climate models; North Atlantic oscillation Index (NAOI); Atmosferische fysica; Atmosferische televerbindingen; Rossby golven; Globale en regionale klimaatmodellen; Noord-Atlantische oscillatie-index; Φυσική; Φυσικές Επιστήμες; άλλοι τομείς; Physical Sciences; Natural Sciences; Physics; miscellaneous; Indian; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10442/hedi/51298; https://doi.org/10.12681/eadd/51298

The atmosphere is a sensitive and highly variable system and its state is crucial for the evolution and well being of all life on Earth. From the ever-recurring changes of the seasons to the most unpredicted extreme weather phenomena, the more we unravel the nature and mechanisms of the physical processes that govern this delicate but powerful system, the more we can benefit and advance towards better extended range forecasts and better understanding of the climate change signals. The atmosphere often reacts vigorously to changes of its state and a local perturbation can influence the weather patterns sometimes even in the most remote regions. Some of those vast spanning patterns are recurring and persisting and are called teleconnections. The extratropical teleconnections can be understood in terms of large-scale waves in the velocity eld of the atmosphere, such as the Rossby waves. The tropical teleconnections involve Rossby waves, as well as atmospheric and oceanic Kelvin waves and strong atmosphere-ocean interactions. The objective of this dissertation is to better understand the interactions between the tropical forcing of Rossby waves and the tropical and extratropical response, with a focus on teleconnections that relate to the Indian Ocean, either directly or indirectly, as studies have shown that even the weather in Europe is influenced by variations in the Indian Ocean. The propagation of Rossby waves is strongly influenced by the presence of a jet stream, that can act as a waveguide and enable a rapid transfer of wave energy around the hemisphere. Major jet streams are found in the upper troposphere of both hemispheres and they are characterized by fast and relatively narrow belts of westerly winds in the extra-tropics. The entrapment of a Rossby wave along the jet stream disturbs its zonal character, creating large meanders that are known as the major ridges and troughs of the midlatitudes, and influences strongly the weather as we know it, by steering air masses and weather systems. However, not all ...