Large-scale atmospheric dynamics of the wet winter 2009–2010 and its impact on hydrology in Portugal

Abstract

The anomalously wet winter of 2010 had a very important impact on the Portuguese hydrological system. Owing to the detrimental effects of reduced precipitation in Portugal on the environmental and socio-economic systems, the 2010 winter was predominantly beneficial by reversing the accumulated precipitation deficits during the previous hydrological years. The recorded anomalously high precipitation amounts have contributed to an overall increase in river runoffs and dam recharges in the 4 major river basins. In synoptic terms, the winter 2010 was characterised by an anomalously strong westerly flow component over the North Atlantic that triggered high precipitation amounts. A dynamically coherent enhancement in the frequencies of mid-latitude cyclones close to Portugal, also accompanied by significant increases in the occurrence of cyclonic, south and southwesterly circulation weather types, are noteworthy. Furthermore, the prevalence of the strong negative phase of the North Atlantic Oscillation (NAO) also emphasises the main dynamical features of the 2010 winter. A comparison of the hydrological and atmospheric conditions between the 2010 winter and the previous 2 anomalously wet winters (1996 and 2001) was also carried out to isolate not only their similarities, but also their contrasting conditions, highlighting the limitations of estimating winter precipitation amounts in Portugal using solely the NAO phase as a predictor.

Are the Winters 2010 and 2012 Archetypes Exhibiting Extreme Opposite Behavior of the North Atlantic Jet Stream?*

“…In fact, wintertime climate variability over most of Europe is strongly reflected in the NAO and EA phases, which are the leading teleconnection patterns of the atmospheric variability in the NA-European sector and closely related to jet variability (Hurrell et al 2001;Pinto and Raible 2012;Wallace and Gutzler 1981;Wanner et al 2001). While the 2010 winter was anomalously wet over southern Europe (Andrade et al 2011;Vicente-Serrano et al 2011) and was also characterized by strong cold outbreaks in northern Europe (Moore and Renfrew 2012;Wang et al 2010), the 2012 winter was anomalously dry in southern Europe and anomalously warm in northern Europe, as will be shown below. As a result of the anomalies in the largescale circulation in the 2010 and 2012 winters, strong anomalies in both precipitation and temperature were recorded all across Europe.…”

“…The large-scale atmospheric circulation over the NA strongly controls not only the mean precipitation and temperature fields over Europe, but also their extremes, particularly in winter, as demonstrated by many previous studies (e.g., Cattiaux et al 2012;Efthymiadis et al 2011;Kenyon and Hegerl 2010;Santos et al 2007;Trigo et al 2004). As persistent anomalies in the atmospheric flow over the NA-European sector tend to yield extremes of precipitation and/or temperature over parts of Europe (e.g., Andrade et al 2012;Garc ıa-Herrera et al 2007;Mahlstein et al 2012), the understanding of their driving mechanisms can provide valuable information for improving seasonal forecasts and climate change projections, both of which are of significant value for many socioeconomic sectors. As persistent anomalies in the atmospheric flow over the NA-European sector tend to yield extremes of precipitation and/or temperature over parts of Europe (e.g., Andrade et al 2012;Garc ıa-Herrera et al 2007;Mahlstein et al 2012), the understanding of their driving mechanisms can provide valuable information for improving seasonal forecasts and climate change projections, both of which are of significant value for many socioeconomic sectors.…”

Surface ozone concentration trends and its relationship with weather types in Spain (2001–2010)

“…Several authors have used this classification method in recent years with the aim of finding a relationship between WTs and different environmental phenomena of natural and anthropogenic origin such as heavy snowfalls, droughts, landslides, soil erosion, and pollution (e.g., Cortesi et al, 2013;Nadal-Romero et al, 2013;Andrade et al, 2011). This paper assesses the temporal variations (i.e., cycles and trends) of surface ozone concentrations for the period 2001e2010 in 3 regions of Spain with different geographical and socioeconomic features and suggests a new hypothesis to explain the increase in ozone concentrations in Spain.…”

Climate change scenarios for precipitation extremes in Portugal

“…Santos et al 2007bSantos et al , 2009a. Andrade et al 2011;Vicente-Serrano et al 2011). Goodess and Jones 2002;Santos et al 2005;Ulbrich et al 1999).…”