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This manuscript applies the recently-created atmospheric river intensity and impacts scale (AR Scale) to the European continent. The AR Scale uses an Eulerian perspective based solely upon the time series of integrated vapor transport (IVT) over a given geographic location (often represented by a model or reanalysis “grid cell”). The scale assigns events with persistent, strong IVT at that location to one of five levels (AR1 to AR5), or if the IVT is too weak or short-lived it is determined not to be an AR. AR1 events are primarily beneficial, AR2, 3 and 4 include a mix of beneficial and hazardous impacts, while AR5s are primarily hazardous. The frequency of occurrence, the associated probability of anomalous precipitation and the amount of precipitation explained by each AR rank are provided across Europe for the extended winter season (from October through March). AR1 and AR2 events are the most frequent and explain most of the observed precipitation, but they are associated with a low probability of extreme rainfall. Although AR3, AR4 and AR5 events are much less frequent, and normally provide a smaller fraction of annual precipitation, they are associated with a high probability of extreme rainfall. These results show remarkable variability among the different regions of the European continent. This manuscript also provides an AR detection catalog over Europe for the period 1980–2019, and a simplified version of the algorithm used to rank the events from AR1 to AR5 Financiado para publicación en acceso aberto: Universidade de Vigo/CISUG Xunta de Galicia | Ref. ED481B 2018/069 Xunta de Galicia | Ref. ED481B 2018/062 Ministerio de Economía y Competitividad | Ref. CGL2015-65141-R Xunta de Galicia | Ref. ED431C 2017/64-GRC Fundação para a Ciência e Tecnologia | Ref. CEECIND / 00027/2017 Fundação para a Ciência e Tecnologia | Ref. PTDC / CTA-MET / 29233/2017 Agencia Estatal de Investigación | Ref. RTI2018-095772-B-I00

[EN] This article presents MERLIN, a tool for flood hazard evaluation, which forecasts discharges and water depths in flood prone areas of the Galicia Costa district. The warning system operates in two stages. During the hindcast stage, hydrological models of the basins included in the system assimilate hydro-meteorological data in order to characterize soil infiltration capacity. During the forecast stage, hydrological models are fed with meteorological predictions and discharge forecasts along the basins. Forecasted discharges define boundary conditions of hydraulic models, which compute the flood extent and the water depths over the upcoming days. The performance of MERLIN was evaluated in 4 areas using discharge data from the winter months of 2019-2020. Results proved MERLIN’s ability of predicting the discharges observed afterwards., [ES] Este artículo presenta MERLIN, una nueva herramienta para estimar el riesgo de inundaciones a partir de predicciones de caudales y calados en Áreas de Riesgo Potencial Significativo de Inundaciones (ARPSIS) de la demarcación hidrográfica Galicia-Costa. El sistema MERLIN opera en dos fases. Durante una primera fase de inicialización, modelos hidrológicos de las cuencas incluidas en el sistema asimilan datos hidro-meteorológicos para caracterizar la capacidad de infiltración del terreno. Durante la fase de predicción, los modelos hidrológicos previamente inicializados se alimentan con predicciones meteorológicas para determinar los caudales esperados durante los próximos días. Las predicciones de caudal alimentan a modelos hidráulicos de las ARPSIS que determinan los calados y la extensión de zonas inundadas. El funcionamiento de MERLIN se evaluó en 4 cuencas piloto a partir de los caudales registrados durante los temporales del invierno del 2019-2020, mostrando una buena capacidad de predecir los valores posteriormente observados., El desarrollo del sistema MERLIN y el resto de trabajos presentados en este artículo fue posible gracias a la financiación aportada por Augas de Galicia dentro del Convenio de colaboración entre Augas de Galicia e a Fundación de Enxeñería Civil de Galicia para a mellora do sistema de alerta temperá de risco de inundación na demarcación hidrográfica Galicia-costa.

Here, the capability of the chemical weather forecasting model CHIMERE (version 2017r4) to reproduce summertime surface ozone, particulate matter and nitrogen dioxide concentrations in complex terrain is investigated. The study area is the northwestern Iberian Peninsula, where both coastal and mountain climates can be found in direct vicinity and a large fraction of the land area is covered by forests. Fed by lateral boundary conditions from the ECMWF Composition Integrated Forecast System, meteorological data from the Weather Research and Forecasting Model (WRF) and the HTAP v2.2 emission inventory, CHIMERE's performance compared to observations is tested with a range of sensitivity experiments, exploring the role of horizontal and vertical resolution and the effects of applying distinct chemistry mechanisms. Using a high horizontal and vertical resolution yields the most balanced verification results. If both the daily maximum and minimum values are important for the given application, then the full Melchior mechanism should be used. If, however, the daily maxima are considered more important than the minima, SAPRC should be used instead. In any case, model performance for nitrogen dioxide is clearly not satisfactory for our study region, probably indicating deficiencies in the emission inventory.

Rias Baixas is a coastal region located in northwestern Spain (Galicia), between Cape Fisterra and the Portugal-Spain border. Its rich natural resources, which are key for the welfare of the region, are highly vulnerable to natural and anthropogenic stress. In this study, the operational ocean forecasting system developed at the meteorological agency of the Galician government (MeteoGalicia) is presented focussing on the Rias Baixas region. This system includes four models providing daily output data: the hydrodynamic models ROMS and MOHID, the atmospheric model WRF and the hydrological model SWAT. Here, MOHID’s implementation for the Rias Baixas region is described and the model’s performance with respect to observations is shown for those locations where Current-Temperature-Depth (CTD) profiles are obtained weekly by the Technological Institute for the Monitoring of the Marine Environment in Galicia (INTECMAR). Although the hydrodynamical conditions of this region are complex, the model skillfully reproduces these CTDs. The model results and derived products are publicly available through MeteoGalicia’s web page and data server (www.meteogalicia.gal).

Atmospheric rivers (ARs) – long and narrow structures of anomalously high water vapor flux located in the warm sector of extratropical cyclones – have been shown to be closely related to extreme precipitation and flooding. In this paper we analyze the connection between ARs and flooding in the northwestern Spanish region of Galicia under a variety of synoptic conditions represented by the so-called “weather types”, a classification of daily sea-level pressure patterns obtained by means of a simple scheme that adopts the subjective procedure of Lamb. Flood events are identified from official reports conducted by the Spanish emergency management agency (Protección Civil) from 1979 to 2010. Our results suggest that, although most flood events in Galicia do not coincide with the presence of an overhead AR, ARs are present in the majority of severe cases, particularly in coastal areas. Flood events associated with ARs are connected to cyclonic weather types with westerly and southwesterly flows, which occur mostly in winter months. The link between ARs and severe flooding is not very apparent in inland areas or during summer months, in which case heavy precipitation is usually not frontal in nature but rather convective. Nevertheless, our results show that, in general, the amount of precipitation in flood events in Galicia more than doubles when an AR is present The authors acknowledge fruitful discussions with Swen Brands and MeteoGalicia. Jorge Eiras-Barca is funded by the “Ministerio Español de Economía y Competitividad” and FEDER (EDRF) (CGL2013-45932-R). This work was partially supported by Xunta de Galicia under project “gts0005 ED431C 2017/64-GRC” Programa de Consolidación e Estruturación de Unidades de Investigación Competitivas (Grupos de Referencia Competitiva) SI

The link between various pathologies and atmospheric conditions has been a constant topic of study over recent decades in many places across the world; knowing more about it enables us to pre-empt the worsening of certain diseases, thereby optimizing medical resources. This study looked specifically at the connections in winter between respiratory diseases and types of atmospheric weather conditions (Circulation Weather Types, CWT) in Galicia, a region in the north-western corner of the Iberian Peninsula. To do this, the study used hospital admission data associated with these pathologies as well as an automatic classification of weather types. The main result obtained was that weather types giving rise to an increase in admissions due to these diseases are those associated with cold, dry weather, such as those in the east and south-east, or anticyclonic types. A second peak was associated with humid, hotter weather, generally linked to south-west weather types. In the future, this result may help to forecast the increase in respiratory pathologies in the region some days in advance.

Coastal upwelling is a phenomenon of great importance both for the study of ocean dynamics and for the development of fish production in some coastal regions. Our study region, the Galician coast, lies at the northern end of the Canary–Iberian Peninsula upwelling system. Knowing the changes provoked by climate change on this upwelling system is particularly relevant for the future of this area taking into account the social and economic importance of fishing activities in this region. In this paper we study the trends in the intensity and frequency of upwelling in the Galician coast and the expected changes in this phenomenon for the next decades using three regional models implemented within the European project ENSEMBLES. As a main result, we observe that the models show a positive trend in both the intensity and frequency of upwelling phenomenon for the future, particularly significant in spring and summer which are the seasons favorable for upwelling. In autumn and winter there are no significant changes.

Climate exerts an important role on grape production and wine quality. For one of the main areas protected under the denomination of origin Rias Baixas, in Galicia, Spain, we explore the relationships among grape production, wine quality, rainfall and temperature for the period 1987–2005. The influence of climatic variability was analysed in terms of the relationship between the productivity of the grapevines and the main meteorological teleconnection patterns affecting the North Atlantic region. We also investigate the daily variation in atmospheric circulation through the study of the influence of weather types derived using an automated daily classification. We consider three bioclimatic indices for viticultural zoning, Winkler and Huglin, and the hydrothermic index of Branas, Bernon and Levadoux. While significant trends were identified in the Winkler and Huglin indices, there were no significant trends in the Branas, Bernon and Levadoux index, for the period 1958–2005. For the coming decades, using the scenario A1B evaluated by the regional climate models used in the ENSEMBLES project, the positive trends of Winkler and Huglin indices continue, while Branas, Bernon and Levadoux implies a negative trend. In all cases, these trends induce significant changes in the viticulture of the region.

The influence of sea surface temperature (SST) of the ocean on seasonal rainfall in Northwestern Iberian Peninsula is studied for the period 1951–2006. Seasonal correlations were calculated for all seasons and different lags applied on SST. A test for field-significance considering the properties of finiteness and interdependence of the spatial grid was applied to avoid correlations by chance. The most significant and repetitive correlation is found between SST over Equatorial Pacific and spring rainfall. The correlation is maintained for different lags, and the common area that satisfies the criteria for statistical field significance is coincident with ENSO area. A forecast scheme is developed to predict spring rainfall anomalies based in SST over ENSO area in precedent seasons. An analysis of principal components was also carried out to obtain the main modes of the Pacific Ocean and their influence on spring rainfall in NWIP. This study concludes that for the period 1951–2006 the negative phase of ENSO, “La Nina”, almost always announces dry springs in NW Iberian Peninsula. However, the positive phase of ENSO, “El Nino”, does not anticipate the appearance of wet springs.

Lorenzo, M. N., Taboada, J. J., and Iglesias, I. 2009. Sensitivity of thermohaline circulation to decadal and multidecadal variability. – ICES Journal of Marine Science, 66: 1439–1447. In this paper, stochastic freshwater inputs with different variabilities are introduced into an Earth Model of Intermediate Complexity to study their effect on the behaviour of the thermohaline circulation (THC). The variability in the stochastic signal was set to be either decadal or multidecadal (70 years), based on intensity modulation of the El Niño-Southern Oscillation (ENSO) phenomenon. The results demonstrate a weakening of the THC in both the decadal and the multidecadal cases. This weakening results in a reduction in air surface temperature, mainly in the North Atlantic. Moreover, the 500-mb stream function also weakens. This causes lower rainfall in Western Europe, except in the areas most influenced by the Gulf Stream. Sea surface temperature is reduced significantly in the area around Greenland, whereas sea surface salinity is reduced around Greenland and in the Gulf Stream, but increased in the Labrador Sea and in Hudson Strait. The latter effects are more marked in the case where the variability of the inputs is multidecadal. The main implication of these results is that the natural decadal or multidecadal variability in freshwater inputs could have noticeable effects on the fate of the THC, which may be superimposed on the effects of climate change.

An automated version of the Lamb weather type classification scheme was used to study the relationship between atmospheric circulation patterns and rainfall in the northwestern part of the Iberian Peninsula, which is an important area of crossing influences of the different teleconnection patterns of the Northern Hemisphere. We calculated the correlation between the most important teleconnection patterns that affect this area and the different types of weather circulation. In this area, anticyclone weather types are the most frequent in any part of the year. The frequency of occurrence of W and SW situations is also significant in autumn and winter. The correlation between weather types (WT) and teleconnection patterns showed that the North Atlantic Oscillation (NAO) index has significant correlations only in winter, while other patterns, such as the Eastern Atlantic (EA), have significant correlations in the other seasons. As a result of these correlations, the EA is a more relevant pattern than the NAO for describing the Galician climate throughout the year. We also calculated correlations between the North Hemisphere Annular Mode (NAM) and the different types of weather types. The NAM shows significant correlations throughout the year. Hence, the NAM is more relevant than the NAO, which is its local manifestation. Copyright © 2007 Royal Meteorological Society

The influence of the preferred modes of variation of the atmosphere in the North Hemisphere on the precipitation variability was evaluated in Galicia (NW Iberian Peninsula). The special location of Galicia requires consideration of the influence of several indices that characterize the atmosphere in order to explain the variability of precipitation and consequently the flow regime of its rivers. We calculate the correlation between the precipitation data obtained from 47 rain-gauge stations covering Galicia from 1977 to 1998 and the five principal teleconnection patterns on the Atlantic area of North Hemisphere (NAO, EA, EA/WR, SCA, and POL). The results obtained show significant correlations between winter precipitation and these patterns, and clear spatial distribution of their influence within Galicia. This result could be related directly to the freshwater discharge in the different Galician Rias each winter, which would improve the hydrodynamical description of these estuaries.

At present both daily and seasonal weather forecasts as well as long-term climate predictions are the result of the implementation of multiple and complex numerical models. The history of numerical models to predict the weather goes back to the 1950s and 1960s and since then computational breakthroughs have enabled us to go from simple box models to complex models that take into account a multitude of phenomena and processes occurring in the whole climate system. However despite the great strides made in recent years and great experience in the development of such models we must interpret the results taking into account the limitations and uncertainties inherent in any numerical model.

The aim of the work described herein was to study projection scenarios in order to find changes in the synoptic variability of the northwest Iberian Peninsula in the 21st century. To this end, we investigated the changes in the frequency of the different circulation types computed for the study area using three different models used in the IPCC 4(th) assessment report. The circulation types were computed using the procedure known as Lamb circulation types. The control simulation for the late 20th century was evaluated objectively from the results obtained using data from the NCEP/NCAR reanalysis, as to evaluate the ability of the model to reproduce the present climate. We have compared not only seasonal mean sea level pressure fields but also the mean seasonal frequency of circulation types. The results for the end of the 21st century show a decrease in the frequency of cyclonic, W, and SW circulation types in the spring and summer months. This trend also appears in the autumn, with a concomitant increase in the anticyclonic types.

Since 1974, there has been a significant increasing trend in land and sea surface temperatures of 0.5 and 0.24 degrees C decade(-1), respectively, in the NW Iberian Peninsula. Over the same period, annual precipitation does not show any trend, although some tendencies have been detected at seasonal scales. A significant positive trend, on average of 2 cm decade(-1), was also observed in sea level rise from 1943 onwards. Ekman transport perpendicular to the coast (upwelling index) showed a decrease from 1975 to 2008 at both annual and seasonal scales. In addition, the flow of the Mino River (the main river in the area) has also decreased at a mean rate of 18 m(3) s(-1) decade(-1) since 1970. At a synoptic scale, winter cyclone frequency and winter and spring blocking activity have decreased since the 1950s, which may partially explain the winter precipitation decline and the winter and spring temperature increases. These changes in synoptic systems are also in agreement with reported trends in the dominant variability modes of atmospheric circulation affecting NW Iberia, particularly a pronounced positive trend in the North Atlantic Oscillation from the 1970s to the 1990s.

This study assesses the relationship between monthly North Atlantic sea surface temperature anomalies (SSTAs) and a regional index of rainfall (NWIPR) in northwest Iberian Peninsula during the period 1951–2006 by means of the Pearson product-moment correlation. Results show a strong influence of SSTA on NWIPR in several months (February, April, May, October and December). The observed persistence of this influence up to 2-months in advance can be used for monthly predictions of rainfall. The most significant areas of the North Atlantic were clustered to be used as input variables in linear regression models. Correlations up to 0.59 between observed and predicted rainfall anomalies were obtained. Predictability ranged from 76 to 86% when considering rainfall as a discrete predictand. Copyright © 2009 Royal Meteorological Society

The nonlinear nature of the climate system suggests that its reactions to unexpected perturbations could be different from the expected ones. In nonlinear science it is recognized as a promising paradigm that stochastic fluctuations can generate order or other counterintuitive effects. Thus, noise sources, adequately coupled to a nonlinear system, may give rise to a rich new phenomenology not present in a deterministic noiseless scenario. In this review we focus attention on thermohaline circulation (THC). THC presents two modes of operation; one state shows active THC and the other inactive. Previous episodes of transitions between both states of THC observed in paleoclimatic records and the influence of this circulation on climate have resulted in detailed investigations on the dynamics of the THC. A weakening or a collapse of this current could trigger the onset of a new Younger Dryas. In this review the introduction of stochastic forcing in key parameters, both in a simple box model and in an earth model of intermediate complexity, provokes a weakening and even a shutdown of the THC. The consequences of this weakening are observed in different variables. The surface air temperature and the sea surface temperature are dominated by cooling of the Northern Hemisphere. Changes in the position of the Intertropical Convergence Zone and in precipitation are observed. There is also an intensification of the North Atlantic Oscillation values during winter. These results reinforce the necessity to consider stochastic sources in climate models to improve our understanding of the climate.

In this paper the effect of the synoptic scale variability is analyzed using a simple atmosphere-ocean coupled model. This high frequency variability has been taken into account in the model adding white gaussian noise in variables related to zonal and meridional temperature differences. Results show that synoptic scale frequency variability on longitudinal heating contrast between land and sea can produce a collapse of thermohaline circulation when a threshold of noise is overcome. This result is significant because if synoptic scale variability in the next century increases due to the climatic change an increment of the probability of this collapse could be produced.

13 páginas, 9 figuras, The Ria de Pontevedra is one of the Galician Rias Baixas, partially mixed estuaries on the north-west coast of the Iberian peninsula. The hydrodynamics of the rias is far from being fully understood. In this application, the hydrodynamics of the Ria de Pontevedra is studied by means of a 3-D baroclinic model. Our aim was to establish the circulation pattern driven by tide and the horizontal density gradient between river and shelf waters under estuarine conditions. The spatial variability of tidal velocities and salinities is studied. The residual component of the flow, related to transport, is described and discussed. As expected in a partially mixed estuary, a double-layered residual pattern is observed, with water flowing seaward in a surface layer and upstream in a bottom layer. A cross-channel residual flow, not described up to date, is presented., This work is part of a Ph.D thesis by M. R. Villarreal, who gratefully acknowledges the support of a predoctoral grant from the Xunta de Galicia (Spain). This research was also carried out in relation to the project ‘ La Hidrodina´mica y el Ciclo Biogeoquímico del Silicio’, financed by the Spanish Comisión Interministerial de Ciencia y Tecnología (CICYT) under the number MAR96-1782.

16 páginas, 5 tablas, 17 figuras, The wind effect on water circulation was described by means of hydrodynamical and thermohaline measurements carried out in the ria of Pontevedra (NW Spain) from February to July 1998. The samples were measured both at an anchored station situated in the inner part of the ria and at other stations located in the main channel. In this way, temporal and spatial events were related. Thermohaline variables (salinity and temperature) were used to clarify the current patterns measured at the anchored station. It has been observed that there is a clear predominance of wind in the main estuary axis direction. The wind direction is strongly dependent on topography. Wind speeds higher than 4 ms 1 are able to dominate the current at surface layers, even against tidal effect. Easterly winds force water to leave the estuary at surface layers while westerly winds force water to enter it. Diurnal breezes associated with westerly winds were rarely recorded. Bottom layers were controlled by tide, except during an upwelling event., This work was partially supported by ‘ Comisión Interministerial de Ciencia y Tecnología ’, under project MAR96-1782.

11 páginas, 7 figuras, 1 tabla, [EN] A two-dimensional hydrodynamic model coupled to a particle tracking model is applied to study the dispersion processes and residence time in two Galician rias (A Coruiia and Vigo, NW Spain) under summer conditions. In A Coruiia a long residence time was found in the harbour area due to the existence of a dock, and a short one in the river area. On the contrary, in Vigo, the residence time is smaller in the harbour area, due to the Rande Strait, beyond which the river effect is negligible., [FR] Un modele hydrodynamique bidimensionel couple a un modele de suivi des particules a Ctd applique a deux rias de Galice (La Corogne et Vigo) pour Ctudier la dispersion et les temps de residence dans les deux estuaires en ttt. Dans la ria de La Corogne, le temps de residence des eaux est important dans la zone portuaire et court a l’embouchure du fleuve. L’inverse est observe dans la ria de Vigo, oti le detroit de Rande limite l’effet du fleuve.

10 páginas, 3 tablas, 4 figuras, A 3D baroclinic model has been applied to study residual circulation in the Rı´a of Vigo (NW Spain) under different seasonal conditions. Winter, spring and non-upwelling summer conditions have been simulated. The use of a 3D model allows the spatial structure of residual circulation to be studied, both horizontaly and verticaly, and the combined effects of bathymetry, freshwater runoff, etc. to be monitored. A two-layered circulation was obtained in all situations, which is in good agreement with the partially-mixed condition of the estuary. This circulation is enhanced with increasing freshwater runoff, while its decrease makes the pattern not to be observed in the outermost part of the Rı´a. The zero residual current level depth has been estimated in all the situations, and the results have been compared to those obtained in the same conditions with a box model, finding a good agreement, J. J. Taboada is supported by Xunta de Galicia (Conselleria de Pesca) under the project ‘ Ordenacion del Espacio Maritimo Terrestre de Galicia: Modelado Informatico

This study analyzes the influence of sea surface temperatures (SSTs) on the second mode of atmospheric variability in the north Atlantic/European sector, namely the East-Atlantic (EA) pattern, for the period 1950-2012. For this purpose, lead-lag relationships between SSTs and the EA pattern, ranging from 0 to 3 seasons, were assessed. As a main result, anomalies of the EA pattern in boreal summer and autumn are significantly related to SST anomalies in the Indo-Pacific Ocean during the preceding seasons. A statistical forecasting scheme based on multiple linear regression was used to hindcast the EA-anomalies with a lead-time of 1 to 2 months. The results of a one-year-out cross-validation approach indicate that the phases of the EA in summer and autumn can be properly hindcast.

Sprial breakup in the Belousov–Zhabotinsky reaction has been observed under the influence of an externally applied alternating electric current. The dynamic mechanism of this breakup is explained in the framework of this reaction. The dependence of the critical electric current amplitude on the period of the wave and on the excitability of the medium is analyzed. Spiral breakup is shown to provide a limit of validity of electric‐field‐induced drift of vortices in excitable media. Experimental results are complemented with numerical simulations provided by two‐ and three‐variable Oregonator models.

13 páginas, 9 figuras, 1 tabla, In order to ameliorate the dearth of existing scientific knowledge concerning the hydrography of the Pontevedra Ria, a systematic investigation was carried out between October 1997–98. Salinity variations were closely related to river discharge whereas bottom waters presented oceanic characteristics over the whole year. Current was controlled by tide, river discharge, and wind in the internal ria where the highest velocities were directed along the ria channel with a low transverse component. Favorable atmospheric conditions in spring induced coastal upwelling up the continental shelf. In May the upwelling was sufficiently strong to be detected in the inner ria and intensified in July and August, cooling the ria water to 12°–14°C. Upwelling ceased in September, and from November to March seawater transported by the poleward current (35.9; 15°C) was detected on the shelf. From January until March, unanticipated favorable upwelling conditions provoked an influx of poleward inside the ria. Ria intrusion of poleward water and association with occasional winter upwelling conditions has not been observed previously. Isopycnic three-dimensional (3-D) surface and 2-D isopycnal maps show that with high river runoff or intense upwelling, lower-salinity water leaves the ria near the northern margin in the surface layer. Under negative upwelling conditions, the water is partially dammed inside the ria and exits the ria when the wind speed falls. During upwelling events, ENACW penetrated the ria, especially near the southern shore. Arrival of ENACW at the northern entrance impedes the outward water flow through this mouth., This work was supported by CICYT under the Spanish project Hydrodynamic and Biogeochemical Cycle of Silicon in the Pontevedra Ria, reference MAR96-1782

The influence of the most representative winter patterns of atmospheric variation in the Northern Hemisphere on precipitation variability and on river flow regimes was evaluated for the Mino River basin (NW Iberian Peninsula). The Arctic Oscillation (AO) was also considered in order to analyze the effect of a larger-scale atmospheric mode on precipitation and river flow. Precipitation data were obtained from 22 rain-gauge stations located within the Mino River basin from 1976 to 1997, and the Mino River flow data were recorded at Frieira gauge station from 1970 to 2005. Both hydrological-year (October to September) time series were averaged for the wet season (December to February). The precipitation variability and river flow in the Mino catchment were shown to have high positive correlation. Relationships with atmospheric circulation modes show that the main pre- cipitation variability, and consequently the river-flow regimes, during winter cannot be explained by a single atmospheric pattern. The temporal evolution (1970-2005) of the correlation between the teleconnection indices and river flow averaged for 22 yr periods showed how all atmospheric patterns evolve with a different trend structure—in such a way that the most prevalent pattern depends on the chosen period of time. Moreover, the time evolution of the correlation between the AO and river flow remains more stationary than for the rest of the indices, due to its larger scale.