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| Titel |
The spatio-temporal distribution of lightning over Israel and the neighboring area and its relation to regional synoptic systems |
| VerfasserIn |
S. Shalev, H. Saaroni, T. Izsak, Y. Yair, B. Ziv |
| 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 ; 11, no. 8 ; Nr. 11, no. 8 (2011-08-04), S.2125-2135 |
| Datensatznummer |
250009613
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| Publikation (Nr.) |
 copernicus.org/nhess-11-2125-2011.pdf |
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| Zusammenfassung |
The spatio-temporal distribution of lightning flashes over Israel and the
neighboring area and its relation to the regional synoptic systems has been
studied, based on data obtained from the Israel Lightning Location System (ILLS) operated by the Israel Electric Corporation (IEC). The system detects
cloud-to-ground lightning discharges in a range of ~500 km around
central Israel (32.5° N, 35° E). The study period was defined for
annual activity from August through July, for 5 seasons in the period
2004–2010.
The spatial distribution of lightning flash density indicates the highest
concentration over the Mediterranean Sea, attributed to the contribution of
moisture as well as sensible and latent heat fluxes from the sea surface.
Other centers of high density appear along the coastal plain, orographic
barriers, especially in northern Israel, and downwind from the metropolitan area
of Tel Aviv, Israel.
The intra-annual distribution shows an absence of lightning during the
summer months (JJA) due to the persistent subsidence over the region. The
vast majority of lightning activity occurs during 7 months, October to
April. Although over 65 % of the rainfall in Israel is obtained during the
winter months (DJF), only 35 % of lightning flashes occur in these months.
October is the richest month, with 40 % of total annual flashes. This is
attributed both to tropical intrusions, i.e., Red Sea Troughs (RST), which
are characterized by intense static instability and convection, and to
Cyprus Lows (CLs) arriving from the west.
Based on daily study of the spatial distribution of lightning, three
patterns have been defined; "land", "maritime" and "hybrid". CLs cause high flash
density over the Mediterranean Sea, whereas some of the RST days are
typified by flashes over land. The pattern defined "hybrid" is a
combination of the other 2 patterns. On CL days, only the maritime pattern
was noted, whereas in RST days all 3 patterns were found, including the
maritime pattern. It is suggested that atmospheric processes associated with
RST produce the land pattern. Hence, the occurrence of a maritime pattern in
days identified as RST reflects an "apparent RST". The hybrid pattern was
associated with an RST located east of Israel. This synoptic type produced
the typical flash maximum over the land, but the upper-level trough
together with the onshore winds it induced over the eastern coast of the
Mediterranean resulted in lightning activity over the sea as well, similar
to that of CLs.
It is suggested that the spatial distribution patterns of lightning may
better identify the synoptic system responsible, a CL, an "active RST" or an
"apparent RST". The electrical activity thus serves as a "fingerprint" for
the synoptic situation responsible for its generation. |
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