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| Titel |
Synoptic climatology of winter intense precipitation events along the Mediterranean coasts |
| VerfasserIn |
M. Reale, P. Lionello |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 7 ; Nr. 13, no. 7 (2013-07-04), S.1707-1722 |
| Datensatznummer |
250018548
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| Publikation (Nr.) |
 copernicus.org/nhess-13-1707-2013.pdf |
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| Zusammenfassung |
| The link between winter (December-January-February) precipitation events at
15 Mediterranean coastal locations and synoptic features (cyclones and
Northern Hemisphere teleconnection patterns) is analyzed. A list of
precipitation events has been produced; q percentile thresholds (Thq)
and corresponding frequency Nq (for q equal to 25, 50, 90 and 98) have
been considered. A negative trend has been detected in total precipitation
and N50 at many locations, while no significant trend in N25,
N90 and N98 has been found. The negative phase of the North
Atlantic Oscillation (NAO) and the East Atlantic/West Russia pattern (EAWR)
compete for exerting the largest influence on the frequency of the 25th, 50th
and 90th percentiles, with EAWR and NAO exerting their largest influence in
the central and western Mediterranean areas, respectively. All percentiles
show a similar behavior except for the 98th percentile, which shows no
convincing link to any teleconnection pattern. The cyclone tracks that are
associated with precipitation events have been selected using the ERA-40
reanalysis data, and a strong link between intense precipitation and cyclones
is shown for all stations. In general, the probability of detecting a cyclone
within a distance of 20° from each station increases with the
intensity of the precipitation event and decreases with the duration of a dry
period. The origin and track of cyclones producing intense precipitation
differ among different areas. When precipitation occurs in the northwestern
Mediterranean, cyclones are generally either of Atlantic origin or secondary
cyclones associated with the passage of major cyclones north of the
Mediterranean Basin, while they are mostly generated inside the region itself
for events at the eastern Mediterranean coast. An important fraction of
intense events in the southern areas is produced by cyclones
that are generated over northern Africa. The analysis of sea level pressure
and geopotential height at 500 hPa highlights the important role of cyclone
depth, circulation strength, surrounding synoptic condition, and of slow
speed of the cyclone center for producing intense precipitation events. |
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