Cloud-to-ground lightning in Portugal: patterns and dynamical forcing
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 to...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2012-03-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | http://www.nat-hazards-earth-syst-sci.net/12/639/2012/nhess-12-639-2012.pdf |
| _version_ | 1818381271835869184 |
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| author | J. A. Santos M. A. Reis J. Sousa S. M. Leite S. Correia M. Janeira M. Fragoso |
| author_facet | J. A. Santos M. A. Reis J. Sousa S. M. Leite S. Correia M. Janeira M. Fragoso |
| author_sort | J. A. Santos |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-14T02:31:56Z |
| format | Article |
| id | doaj.art-478ed91f1ead446cafaee00d7f16bda2 |
| institution | Directory Open Access Journal |
| issn | 1561-8633 1684-9981 |
| language | English |
| last_indexed | 2024-12-14T02:31:56Z |
| publishDate | 2012-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Natural Hazards and Earth System Sciences |
| spelling | doaj.art-478ed91f1ead446cafaee00d7f16bda22022-12-21T23:20:13ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812012-03-0112363964910.5194/nhess-12-639-2012Cloud-to-ground lightning in Portugal: patterns and dynamical forcingJ. A. SantosM. A. ReisJ. SousaS. M. LeiteS. CorreiaM. JaneiraM. FragosoAn 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.http://www.nat-hazards-earth-syst-sci.net/12/639/2012/nhess-12-639-2012.pdf |
| spellingShingle | J. A. Santos M. A. Reis J. Sousa S. M. Leite S. Correia M. Janeira M. Fragoso Cloud-to-ground lightning in Portugal: patterns and dynamical forcing Natural Hazards and Earth System Sciences |
| title | Cloud-to-ground lightning in Portugal: patterns and dynamical forcing |
| title_full | Cloud-to-ground lightning in Portugal: patterns and dynamical forcing |
| title_fullStr | Cloud-to-ground lightning in Portugal: patterns and dynamical forcing |
| title_full_unstemmed | Cloud-to-ground lightning in Portugal: patterns and dynamical forcing |
| title_short | Cloud-to-ground lightning in Portugal: patterns and dynamical forcing |
| title_sort | cloud to ground lightning in portugal patterns and dynamical forcing |
| url | http://www.nat-hazards-earth-syst-sci.net/12/639/2012/nhess-12-639-2012.pdf |
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