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| Titel |
Cluster analysis applied to the synoptic patterns of lightning wildfire days in Castile and León (Spain) |
| VerfasserIn |
Eduardo García-Ortega, María Teresa Trobajo, Laura López |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035549
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| Zusammenfassung |
| Wildfires are the main disruptive and destructive agent in the natural environment of Castile
and León region (Spain). Covering a total of 94225 km2, and with a forest area of
nearly 50000 km2, Castile and León is one of the regions with the greatest forest
mass in all of Europe. 8% of the fires that occur in this region are due to lightning
strikes during thunderstorms, although in some years they represent more than 20%
of the total burnt surface. During the period from 1985 to 2006, there were 376
wildfire days (WD) with 976 wildfires caused by lightning, covering more than 1
hectare.
The formation of storms requires the interaction of several dynamic and thermodynamic
mechanisms on different scales. Convective systems depend primarily on large-scale
processes that develop an adequate thermodynamic structure, whereas processes on a
mesoscale act basically at the beginning of the convective phenomenon. The synoptic scale
atmospheric patterns and their relationship with local weather play an important role in the
occurrence of hailstorms, through its controlling effect on the formation of local
thermodynamic regimes.
In this study we have made a classification at synoptic scale of the conditions of the
atmosphere on the 376 WD that affected different areas in Castile and León. As a
first step, a Principal Component Analysis in T-mode was carried out on the initial
ensemble of meteorological fields, followed by a Cluster Analysis of the days,
based on the retained principal component loadings. Days participating with similar
loadings on the extracted components were clustered together. The seven atmospheric
fields selected at low and mid-levels were the 850 and 500 hPa geopotential height
and temperature and the 850 hPa relative humidity and horizontal components of
wind.
The non-hierarchical CA was applied to a total matrix of 64 loadings of the 376 events.
Four cluster elements were retained. The results make it possible to establish the atmospheric
conditions which, at synoptic scale, favour the formation of convective events that lead
to wildfires in the different zones of a region as extensive as Castile and León. |
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