Μελέτη διασύνδεσης ανωμαλιών της ατμοσφαιρικής κυκλοφορίας στο βόρειο ημισφαίριο που δημιουργούνται κατά τη διάρκεια ακραίων κλιματικών φαινομένων στην ανατολική Μεσόγειο

• Main Authors: Oikonomou, Christina, Οικονόμου, Χριστίνα
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: National and Kapodistrian University of Athens 2009
• Subjects: Ατμοσφαιρική κυκλοφορία; Ακραίες ξηρές και υγρές περίοδοι; Ατμοσφαιρική Τηλεσύνδεση; Κλιματικά μοντέλα; Ανάλυση Μοναδιαίων Τιμών; Κλιματικοί δείκτες; Βροχόπτωση; Μεσόγειος θάλασσα; Ανατολική; Teleconnections; Extreme climatic precipitation events; Singular value decomposition analysis; Regional climatic model; Consecutive dry days; Consecutive wet days; Canonical correlation analysis; Φυσικές Επιστήμες; Φυσική; Natural Sciences; Physical Sciences; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10442/hedi/24304; https://doi.org/10.12681/eadd/24304

In this thesis, the relationship of prolonged dry and wet spells in Eastern Mediterranean with large-scale surface and upper circulation over the Northern Hemisphere, as well as the impact of orography on these spells in Greece are investigated. First, a climatological analysis of extreme dry and wet spells in Eastern Mediterranean is accomplished, on seasonal basis, concerning the time period 1958-2000, using daily observational precipitation data. The extreme dry and wet spells are defined by means of the climatic indices, CDD (Consecutive Dry Days) and CWD (Consecutive Wet Days) respectively. Then, estimating the number of stations exceeding the 0.95 percentile of CDD and CWD values, the “extreme dry and wet seasons” were defined, while using the Generalized Extreme Value Distribution (GEV) the return level of the longest dry and wet spells with frequency of occurrence 50 years were assessed. The linkage between the large scale circulation patterns prevailing over the North Hemisphere during extreme dry and wet periods in Eastern Mediterranean was investigated using the statistical method Singular Value Decomposition Analysis (SVDA). Since SVDA is a newly appeared method, the widely used CCA was performed and the results of both methods were compared for extreme dry spells data.The impact of orography on prolonged wet and dry spells was investigated over Greece, during two “extreme seasons” (winter 1984, summer 1993), employing the regional climate model RegCM3.1. It was found that North Turkey and West Greece present the largest extreme wet spells for all seasons and are most vulnerable to extremely long wet spells compared to the rest areas. Generalized Extreme Value Distribution (GEV) can fit well on CDD and CWD station data, for all seasons except from summer. The duration of maximum dry and wet periods over Eastern Mediterranean is affected by the combined surface and upper level large-scale circulation over the greater Atlantic area and Europe (North Atlantic Oscillation, Eastern Mediterranean Pattern, ...