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Universidade de Lisboa (2019)

Identification of iberian large fires climate conditions

Vieira, Inês dos Santos

Titre : Identification of iberian large fires climate conditions

Auteur : Vieira, Inês dos Santos

Université de soutenance : Universidade de Lisboa

Grade : Mestrado em Ciências Geofísicas (Meteorologia e Oceanografia), 2019

The Mediterranean region is characterized by the frequent occurrence of summer wildfires representing an environmental and socioeconomic burden. Some Mediterranean countries (or provinces) are particularly prone to Large Fires (LF), namely Portugal, Galicia, Greece, and southern France. On the other hand, the Mediterranean basin corresponds to a major hotspot of climate change, and anthropogenic warming is expected to increase the total burned area due to fires in Mediterranean Europe. Here, we propose to classify summer large fires for four regions of Iberia (with similar fire regimes) according to their local-scale weather conditions (i. e. temperature, relative humidity, wind speed) and fire danger weather indices (Duff Moisture Code and Drought Code). The composite analysis was used to investigate the impact of local and regional climate drivers at different time scales, and to identify distinct climatologies associated with the occurrence of LF in Iberia for an extended fire season (May to October). A Principal Component Analysis (PCA) was applied to identify the variables with the highest variance explained for the fire day. Also, cluster analysis was used to identify a limited set of Fire Weather Types (FWT), each characterized by a combination of meteorological conditions leading to a better understanding of the relationship between meteorology and fire. For each of the regions, three FWTs were identified with different characteristics. The FWT_1 is characterized by high anomalies (above one std) of zonal wind velocity. The FWT_2 presents anomalies of the meteorological variables within the average (bellow one std). Finally, the FWT_3 is categorized by high positive temperature anomalies (above one std) and strong negative relative humidity anomalies (bellow one std). The methodology followed allowed to objectively identify for different regions of Iberia multiple fire climatologies associated with the occurrence of LF.


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