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Cloud-to-ground lightning in Portugal: patterns and dynamical forcing
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Orientador(es)
Resumo(s)
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.
Descrição
Palavras-chave
Lightning Portugal Cloud-to-ground discharges
Contexto Educativo
Citação
Santos, J. A., Reis, M. A., Sousa, J., Leite, S. M., Correia, S., Janeira, M., & Fragoso, M. (2012). Cloud-to-ground lightning in Portugal: patterns and dynamical forcing. Nat. Hazards Earth Syst. Sci.,12, 639-649. https://doi.org/10.5194/nhess-12-639-2012, 2012
Editora
Copernicus Publications