http://hdl.handle.net/10174/37677 2026-04-06T23:43:15Z http://hdl.handle.net/10174/41685 Title: Synoptic and Regional Meteorological Drivers of a Wildfire in the Wildland–Urban Interface of Faro (Portugal) Authors: Couto, Flavio Tiago; Campos, Cátia; Purificação, Carolina; Santos, Filippe Lemos Maia; Andrade, Hugo Nunes; Andrade, Nuno; Nunes, André Becker; Guiomar, Nuno; Salgado, Rui Abstract: A major fire occurred in the wildland–urban interface in southern Portugal, on 13 July 2022, becoming uncontrolled due to weather conditions. This study investigates how atmospheric dynamics increased fire danger in Mainland Portugal during early July 2022. The synoptic circulation from European Centre for Medium-Range Weather Forecasts (ECMWF) analysis and mesoscale conditions from Meso-NH model simulation at 1.5 km resolution revealed atmospheric conditions before and during the fire. Fire risk was assessed using the Fire Weather Index (FWI) from Meso-NH outputs. A blocking pattern was configured by an upper-level low-pressure system in early July, remaining semi-stationary west of Mainland Portugal until 18 July. The counter-clockwise circulation of the cut-off low resulted in dry, warm air advection from North Africa, enhancing fire danger over the Iberian Peninsula. In southern Portugal, a jet-like wind with strong east/southeasterly flow from Gibraltar Strait favored rapid fire spread. This circulation below 1 km altitude from the Mediterranean Sea enhanced fire danger through strong winds, independent of the large-scale blocking pattern. This study presents an atmospheric scenario for evaluating fire danger in Southern Portugal, important for pre-firefighting management that complemented previous studies for the region. Also, high-resolution FWI calculations using Meso-NH emphasized the importance of improved temporal and spatial resolution for fire danger assessment. 2025-09-10T23:00:00Z http://hdl.handle.net/10174/41684 Title: EXPLORATORY ANALYSIS OF ATMOSPHERIC MODELLING USE OVER PANTANAL WILDFIRES Authors: Couto, Flavio Tiago; Santos, Filippe L. M.; Campos, Cátia; Purificação, Carolina; Andrade, Nuno; López-Vega, Juan Manuel; Lacroix, Matthieu Abstract: The study discusses in an exploratory way the atmospheric conditions leading to several fires in the Pantanal on November 12, 2023. These episodes were marked by two periods of maximum fire expansion, first in the early afternoon and another in the evening. The study is based on a set of observations from satellites and weather stations, which helped to identify these fires and some meteorological conditions at the surface. In addition, the Fire Weather Index (FWI) in the Pantanal was analyzed for a 44-year period. However, this dataset was not enough to completely explain the fire behavior on that day. In this context, atmospheric modeling was applied to find the possible causes of fire behavior in these two periods. The Meso-NH model was run with two nested domains of horizontal resolutions of 2500 m and 500 m. The results showed a positive trend of FWI in the last decades and a clear seasonality for the maximum values in 2023. Also, the simulation indicated favorable weather conditions for fire ignition, given the high temperatures and low relative humidity. However, the wind gust field showed moderate gusty winds in both periods but caused by different forces. In the early afternoon, the larger scale circulation favored fire propagation, whereas in the evening fire spread by a gust front. Furthermore, the findings highlight the role of weather conditions on a sub-daily scale, with sudden changes in surface winds throughout the day, which is strongly recommended to be considered when examining fire danger and firefighting action plans in the region. 2025-08-19T23:00:00Z http://hdl.handle.net/10174/41682 Title: Fire-weather conditions during two fires in Southern Portugal: Meteorology, Orography, and Fuel Characteristics Authors: Purificação, Carolina; Santos, Filippe L. M.; Henkes, Alice; Kartsios, Stergios; Couto, Flavio Tiago Abstract: The interactions between meteorology, orography and fuel have a major impact on fire dynamics, influencing its behaviour. This study presents the results about the atmospheric environment and surface aspects of two wildfires that occurred in Southern Portugal. Two numerical simulations were performed by the Meso-NH atmospheric model using a two-way nested domain configuration with horizontal resolutions of 2500 m and 500 m, respectively. Furthermore, observations of land use/land cover and live fuel moisture content analysis for each wildfire were used to understand the land occupation and vegetation dynamics. Both cases present significant fuel variability with low live fuel moisture content, showing high probability of fire occurrence over the region. The analysis of Castro Marim’s fire with ignition during the nighttime, presented critical fire weather conditions, namely high air temperatures and low relative humidity, even overnight. Furthermore, the interaction of the northerly flow with the local terrain led to the spread of the fire to southeast and south westward. In the second case study, Odemira’s fire exhibited a complex environment marked by continual shifts in wind direction. However, the study highlights the strong southeasterly flow prevailing from the Gibraltar Strait reaching the Algarve region and producing intense winds in the local mountains. Algarve region contains forest species such as maritime pine and eucalyptus in large variations of altitude that are highly susceptible to the occurrence of wildfires if the forests are not adequately manage, significantly threatening the safety of front-line firefighters. In a regional context, the present study shows that the use of atmospheric modelling can be useful in assessing fire risk when also the surface aspects obtained from remote sensing observations are considered. 2025-02-15T00:00:00Z http://hdl.handle.net/10174/41680 Title: Relationship Between the Water Vapor Transport from the Amazon Basin and the Rainfall Regime over a Watershed on Brazil’s Southern Border Authors: Santiago, Maicon Moraes; Nunes, André Becker; Couto, Flavio Tiago; Almeida Bressiani, Danielle; Freitas, Rose Ane Pereira; Cardoso, Iulli Pitone Abstract: The climate of the south of Brazil is characterized by northern winds in a hegemonic way for the transfer of moisture. Thus, the goal here is to verify the impact of the meridional water vapor transport on the rainfall of the Mirim–São Gonçalo Watershed (MSGW), located in the extreme south of Brazil and essential for regional development. The study is based on the precipitation data from MSGW weather stations and ERA5 reanalysis data for the period 1981–2020, which allowed the analysis of the interactions between different climatological variables. The water vapor transport was analyzed using the vertically integrated water vapor flux (VIVF). Coefficients were obtained according to the VIVF values in two locations placed between the Amazon basin and southern Brazil, namely in Bolivia and Paraguay. The results show that the MSGW is directly impacted by moisture transport from the north in all seasons, and this transport is most significant at the 850 hPa level. In addition, the moisture and rainfall in the MSGW are also influenced by changes in the magnitude and direction of this flow, with an increase in transport in periods of El Niño, especially during spring. Therefore, the study brings insights into how changes in tropical South American climate, through a cascading effect, may affect the Mirim–São Gonçalo Watershed development in the middle latitudes from changes in the meridional water vapor transport, highlighting the importance of studying the tropical and extratropical interactions in South America for the MSGW management and sustainable development. 2025-02-24T00:00:00Z