Comparison of lightning activity in the two most active areas of the Congo Basin
A comparison of the lightning activity in the two most active areas (Area_max for the main maximum and Area_sec for the secondary maximum) of the Congo Basin is made with data obtained by the World Wide Lightning Location Network (WWLLN) during 2012 and 2013. Both areas of same size (5° × 5°)...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-02-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://www.nat-hazards-earth-syst-sci.net/18/479/2018/nhess-18-479-2018.pdf |
| Summary: | A comparison of the lightning activity in the two most active areas
(Area_max for the main maximum and Area_sec for the secondary maximum) of
the Congo Basin is made with data obtained by the World Wide Lightning
Location Network (WWLLN) during 2012 and 2013. Both areas of same size
(5° × 5°) exhibit flash counts in a ratio of about 1.32
for both years and very different distributions of the flash rate density
(FRD) with maximums in a ratio of 1.94 and 2.59 for 2012 and 2013,
respectively. The FRD is much more widely distributed in Area_sec, which
means the whole area contributes more or less equal to the lightning
activity. The diurnal cycle is much more pronounced in Area_max than in
Area_sec with a ratio between the maximum and the minimum of 15.4 and 4.7,
respectively. However, the minimum and maximum of the hourly flash rates are
observed roughly at the same time in both areas, between 07:00 and 09:00 UTC
and between 16:00 and 17:00 UTC, respectively. In Area_sec the proportion
of days with low lightning rate (0–1000 flashes per day) is much larger
(∼ 45 % in 2013) compared to Area_max
(∼ 23 % in 2013). In Area_max the proportion of days with
moderate lightning rate (1001–6000 flashes per day) is larger
(∼ 68.5 % in 2013) compared to Area_sec
(∼ 46 % in 2013). The very intense convective events are
slightly more numerous in Area_sec. In summary, the thunderstorm activity in
Area_sec is more variable at different scales of time (annually and daily),
in intensity and in location. Area_max combines two favourable effects for
thunderstorm development, the convergence associated with the African
easterly jet of the Southern Hemisphere (AEJ-S) and a geographic effect due
to the orography and the presence of a lake. The location of the strong
convection in Area_sec is modulated by the distance of westward
propagation/regeneration of mesoscale convective systems (MCSs) in relation to the phase of Kelvin waves. |
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| ISSN: | 1561-8633 1684-9981 |