Jetstream and rainfall distribution in the Mediterranean region

Gaetani, Marco; Baldi, Marina; Dalu, G.; Maracchi, Giampiero

doi:10.5194/nhess-11-2469-2011

Cited by 29 publications

(23 citation statements)

References 45 publications

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“…In August, the highest geopotential values are located between 20°W and 20°E, which is directly related to the Saharan High and between 40° and 50°E, which is directly related to the Arabian High. In between these highs is a trough that is associated with the subtropical westerly jet stream over the Mediterranean region (Gaetani et al , ). Observations from the Hovmoller diagram of geopotential, the Saharan High shows propagation between August 11 and 21.…”

Section: Resultsmentioning

confidence: 99%

Effects of the subtropical anticyclones over North Africa and Arabian Peninsula on the African easterly jet

Spinks

Lin

Mekonnen

2014

Intl Journal of Climatology

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North African climate is analysed between 1979 and 2010 with an emphasis on August using the European Center for Medium‐Range Weather Forecast (ECMWF) global dataset to investigate the effects of the subtropical anticyclones over North Africa and the Arabian Peninsula on the African easterly jet (AEJ). It was found that the AEJ encloses a core with a local wind maximum (LWM) in both West and East Africa, in which the west LWM core has a higher zonal wind speed. The strength of both cores is distinctly different by way of thermal wind balance. As found in previous studies, the AEJ is formed through baroclinicity with influence from Saharan lower level heating along and to the north of the Intertropical Front (ITF). As there are two separate anticyclonic centres, the AEJ is maintained by the anticyclonic systems in West Africa, East Africa as well as the Arabian Peninsula. The presence of these two anticyclonic centres provides the AEJ with two separate core maxima with the western LWM located at 15°W, 17°N and the eastern LWM located at 35°E, 15°N for August.

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Section: Resultsmentioning

confidence: 99%

Effects of the subtropical anticyclones over North Africa and Arabian Peninsula on the African easterly jet

Spinks

Lin

Mekonnen

2014

Intl Journal of Climatology

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“…The cross-jet circulation of the Atlantic jet favours storm activity in its exit region, while the cross-jet circulation of the African jet suppresses this kind of activity in its entrance region. It follows that the rainfall distribution downstream of these cross-jet circulations is strongly influenced by their relative positions (Gaetani et al, 2011;Toreti et al, 2010). Specifically, in autumn, rainfall is copious and more persistent in the western Mediterranean Basin when the Atlantic jet is relatively strong but its northeasterly tilt is small, and the African jet is in its easternmost position.…”

Section: Local or Global?mentioning

confidence: 97%

Floods and climate: emerging perspectives for flood risk assessment and management

Merz

Aerts

Arnbjerg‐Nielsen

et al. 2014

Nat. Hazards Earth Syst. Sci.

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271

165

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Abstract. Flood estimation and flood management have traditionally been the domain of hydrologists, water resources engineers and statisticians, and disciplinary approaches abound. Dominant views have been shaped; one example is the catchment perspective: floods are formed and influenced by the interaction of local, catchment-specific characteristics, such as meteorology, topography and geology. These traditional views have been beneficial, but they have a narrow framing. In this paper we contrast traditional views with broader perspectives that are emerging from an improved understanding of the climatic context of floods. We come to the following conclusions: (1) extending the traditional system boundaries (local catchment, recent decades, hydrological/hydraulic processes) opens up exciting possibilities for better understanding and improved tools for flood risk assessment and management. (2) Statistical approaches in flood estimation need to be complemented by the search for the causal mechanisms and dominant processes in the Published by Copernicus Publications on behalf of the European Geosciences Union. B. Merz et al.: Floods and climate: emerging perspectives for flood risk assessment and managementatmosphere, catchment and river system that leave their fingerprints on flood characteristics. (3) Natural climate variability leads to time-varying flood characteristics, and this variation may be partially quantifiable and predictable, with the perspective of dynamic, climate-informed flood risk management. (4) Efforts are needed to fully account for factors that contribute to changes in all three risk components (hazard, exposure, vulnerability) and to better understand the interactions between society and floods. (5) Given the global scale and societal importance, we call for the organization of an international multidisciplinary collaboration and datasharing initiative to further understand the links between climate and flooding and to advance flood research.

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“…As the STJ slides to the north of Himalayas and Tibet at about 40°N and reforms over central Asia during the summer months, the summer monsoon cell finally develops (Ramaswamy, 1962;Pai and Rajeevan, 2007;Yin, 1949). This is especially important for climatic variability in the EM, since during summer the intensity and position of the STJ over the Mediterranean are key parameters for the climate variability over the region regarding heat wave events and precipitation (Baldi et al, 2006;Brikas et al, 2006;Gaetani et al, 2011;Prezerakos and Flocas, 2002).…”

Section: Ism and Upper Level Circulationmentioning

confidence: 99%

Relationship between the Indian summer monsoon and the large-scale circulation variability over the Mediterranean

Rizou

Flocas

Athanasiadis

et al. 2015

Atmospheric Research

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In this study the impact of the Indian summer monsoon on the large scale variability of the atmospheric circulation over the Mediterranean is investigated on an inter-annual time scale. Composite and correlation analysis results are presented, outlining different circulation patterns in the upper and lower troposphere for strong and weak monsoon years respectively. For this purpose ERA-40 Reanalysis monthly mean data at various isobaric levels together with the standardized All India Rainfall Index for boreal summer (June-July-August-September) of a 44-year period were employed. During strong monsoon years many atmospheric circulation systems appear strengthened over Eurasia, resembling a well-organized Rossby wave train over the area. In the upper troposphere a meridional shift of the jet streams over the examined area was also identified during extreme monsoon years. On the other hand, in the lower troposphere enhanced northerlies (Etesians) appear to dominate over Eastern Mediterranean along with intensified subsidence during strong monsoon years.

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Jetstream and rainfall distribution in the Mediterranean region

Abstract: Abstract. This is a study on the impact of the jetstream in

Cited by 29 publications

References 45 publications

Effects of the subtropical anticyclones over North Africa and Arabian Peninsula on the African easterly jet

Effects of the subtropical anticyclones over North Africa and Arabian Peninsula on the African easterly jet

Floods and climate: emerging perspectives for flood risk assessment and management

Relationship between the Indian summer monsoon and the large-scale circulation variability over the Mediterranean

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