 |
| Titel |
Cloud-to-ground lightning over Mexico and adjacent oceanic regions: a preliminary climatology using the WWLLN dataset |
| VerfasserIn |
B. Kucienska, G. B. Raga, O. Rodriguez |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 11 ; Nr. 28, no. 11 (2010-11-09), S.2047-2057 |
| Datensatznummer |
250016909
|
| Publikation (Nr.) |
 copernicus.org/angeo-28-2047-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
This work constitutes the first climatological study of lightning over
Mexico and adjacent oceanic areas for the period 2005–2009. Spatial and
temporal distributions of cloud to ground lightning are presented and the
processes that contribute to the lightning variability are analysed.
The data are retrieved from the World Wide Lightning Location Network
(WWLLN) dataset. The current WWLL network includes 40 stations which cover
much of the globe and detect very low frequency radiation ("spherics")
associated with lightning.
The spatial distribution of the average yearly lightning over the
continental region of Mexico shows the influence of orographic forcing in
producing convective clouds with high lightning activity. However, a very
high number of strikes is also observed in the States of Tabasco and
Campeche, which are low-lying areas. This maximum is related to the
climatological maximum of precipitation for the country and it may be
associated with a region of persistent low-level convergence and convection
in the southern portion of the Gulf of Mexico.
The maps of correlation between rainfall and lightning provide insight into
the microphysical processes occurring within the clouds. The maritime clouds
close to the coastline exhibit similar properties to continental clouds as
they produce very high lightning activity.
The seasonal cycle of lightning registered by WWLLN is consistent with the
LIS/OTD dataset for the selected regions. In terms of the annual
distribution of cloud-to-ground strikes, July, August and September exhibit
the highest number of strikes over continental Mexico. The diurnal cycle
indicates that the maximum number of strikes over the continent is observed
between 6 and 9 p.m. LT.
The surrounding oceanic regions were subdivided into four distinct sectors:
Gulf of Mexico, Caribbean, Sub-tropical Pacific and Tropical Pacific. The
Gulf of Mexico has the broadest seasonal distribution, since during winter
lightning associated with mid-latitude systems also affects the region. The
diurnal distribution of lightning for the Gulf of Mexico exhibits the
highest number of strokes at 9 a.m. The Caribbean seasonal distribution is
slightly biased towards early fall, with a clear maximum observed during
October. The diurnal distribution of lightning over the Caribbean is quite
uniform with a slight increase near midnight. The Subtropical Pacific has
the narrowest seasonal distribution, associated with the convection observed
during the "North American Monsoon", with the maximum number of strikes
during August and September. In contrast, the Tropical Pacific has a broader
seasonal cycle, associated with convection in the Inter-Tropical Convergence
Zone (ITCZ), starting in May and lasting till October. In both adjacent
Pacific regions, the strikes present a maximum in the early morning, the
time of the highest frequency of land breeze. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|