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| Titel |
Cloud-to-ground lightning in Portugal: patterns and dynamical forcing |
| VerfasserIn |
J. A. Santos, M. A. Reis, J. Sousa, S. M. Leite, S. Correia, M. Janeira, M. Fragoso |
| 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 ; 12, no. 3 ; Nr. 12, no. 3 (2012-03-16), S.639-649 |
| Datensatznummer |
250010608
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| Publikation (Nr.) |
 copernicus.org/nhess-12-639-2012.pdf |
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| Zusammenfassung |
| An analysis of the cloud-to-ground discharges (CGD) over Portugal is carried
out using data collected by a network of sensors maintained by the
Portuguese Meteorological Institute for 2003–2009 (7 yr). Only
cloud-to-ground flashes are considered and negative polarity CGD are largely
dominant. The total number of discharges reveals a considerable interannual
variability and a large irregularity in their distribution throughout the
year. However, it is shown that a large number of discharges occur in the
May–September period (71%), with a bimodal distribution that peaks in
May and September, with most of the lightning activity recorded in the
afternoon (from 16:00 to 18:00 UTC). In spring and autumn the lightning
activity tends to be scattered throughout the country, whereas in summer it
tends to be more concentrated over northeastern Portugal. Winter generally
presents low lightning activity. Furthermore, two significant couplings
between the monthly number of days with discharges and the large-scale
atmospheric circulation are isolated: a regional forcing, predominantly in
summer, and a remote forcing. In fact, the identification of daily lightning
regimes revealed three important atmospheric conditions for triggering
lightning activity: regional cut-off lows, cold troughs induced by remote
low pressure systems and summertime regional low pressures at
low-tropospheric levels combined with a mid-tropospheric cold trough. |
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