Consecutive Extratropical Cyclones Daniel, Elsa and Fabien, and Their Impact on the Hydrological Cycle of Mainland Portugal

Abstract

The extratropical cyclones that originate in the North Atlantic and propagate towards Europe are one of the major natural hazards in mid-latitudes. In December 2019, three consecutive extratropical cyclones named Daniel, Elsa, and Fabien affected Portugal. In this study, the synoptic and upper-level dynamic conditions associated with these systems during their impact in mainland Portugal are evaluated. The persistent intense zonal flow that crossed the entire Atlantic revealed by the integrated vapor transport and the vertically integrated moisture flux favored these hydro-meteorological systems. The patterns of mean sea level pressure, geopotential, potential vorticity, total column water, and convective available potential energy were used to characterize the influence of every system over mainland Portugal. A cluster analysis of monthly precipitation permitted the classification of the country into four main regions named the Northwest, Centre West, Northeast and Centre East, and South region on which the analysis was focused. The three storms affected every region on consecutive days by the middle of December, producing extreme precipitation events and significant effects on the accumulated rainfall and runoff, particularly in the Northwest, Centre West, Northeast and Centre East regions. As consequence, multiple incidences of damage were reported along mainland Portugal. However, an assessment of the Standardized Precipitation Index (SPI) and the Standardized Precipitation–Evapotranspiration Index (SPEI) on time scales of 1, 3, 6, and 12 months revealed a positive impact of rainfall increase on the attenuation of short and long term accumulated drought conditions, particularly in the center and north regions.

Convolutional Neural Network and Optical Flow for the Assessment of Wave and Tide Parameters from Video Analysis (LEUCOTEA): An Innovative Tool for Coastal Monitoring

“…The coast of south-eastern Sicily and the Atlantic side of Portugal are greatly influenced by storm events, medicanes [46,103,104], and hurricanes [32,62,63]. Both areas are characterized by the development of Tropical Like Cyclone for the Tropical transition of an extratropical system.…”

“…Tropical Transition is the natural process responsible for the transformation of an extra tropical system into a tropical system. In addition, a recent study [61,63], based on a climate change scenario showing 1 °C less global warming than the SRES A1B scenario [64,65], suggests an eastward extension of the development region of tropical The Portuguese coastline extends for approximately 990 km. It is divided into different geomorphological units represented by sandy beaches, dunes, sand, and rocky cliffs, combined with river mouths, estuaries, lagoonal systems, and anthropogenic areas (Figure 2a,b).…”

“…Tropical Transition is the natural process responsible for the transformation of an extra tropical system into a tropical system. In addition, a recent study [61,63], based on a climate change scenario showing 1 • C less global warming than the SRES A1B scenario [64,65], suggests an eastward extension of the development region of tropical storms. In the current climate, the main genesis region for hurricanes is confined to the western tropical Atlantic, where sea surface temperatures are above the threshold (27 • C) required for tropical cyclones to develop.…”

Precipitation Moisture Sources of Ethiopian River Basins and Their Role During Drought Conditions

“…Therefore, we used Ward's hierarchical clustering method (Wilks, 2011;Bednorz et al, 2019) to determine the similarity in precipitation regimes between Ethiopia's 12 major drainage systems. Ward's method has been commonly used among several hierarchical clustering methods, and it has been widely applied by different researchers to define consistent precipitation zones (Munoz-Díaz and Rodrigo 2004;Ferreira and Hitchcock 2009;Murtagh and Legendre, 2014;Zhang et al, 2016;Sharghi et al, 2018;Stojanovic et al, 2021a;Beyene et al, 2021). Ward's method was employed with Euclidean distance used as similarity measurement.…”

The rare case of Hurricane Catarina (2004) over the South Atlantic Ocean: The origin of its precipitation through a Lagrangian approach

“…Tropical and extratropical cyclones (TCs and ECs, respectively) play an important role in the hydrological cycle across extended areas around the world (Trigo, 2006;Reboita et al, 2010a;Liberato et al, 2011Liberato et al, , 2013Grise et al, 2013;Prat and Nelson, 2013;Khouakhi et al, 2017;Utsumi et al, 2017;Touma et al, 2019;Fernández-Alvarez et al, 2020;Raible et al, 2021;Stojanovic et al, 2021). For example, Khouakhi et al (2017) noted that the highest contribution of TCs to the annual rainfall amounts occurred in East Asia, followed by northeastern Australia and the southeastern United States.…”