Towards a better assessment of the historical climate of Extremadura region (SW Spain)

2020 ◽  
Author(s):  
José Manuel Vaquero ◽  
María Cruz Gallego ◽  
Víctor M. S. Carrasco ◽  
Nieves Bravo-Paredes ◽  
María Ángeles Obregón ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Main Task ◽  
Winter Climate ◽  
Historical Climate ◽  
The North ◽  
Nao Index ◽  
Dry Conditions ◽  
Good Proxy ◽  
The North Atlantic Oscillation ◽  
The Impact

<p>Our efforts to a better understanding of the historical climate of the region of Extremadura (interior of the SW Iberia) have been directed in two main aspects. First, we have tried to recover all the meteorological data of the pre-instrumental period. Second, we have been working on the localization and analysis of proxy data, including “pro-pluvia” rogation ceremonies and a chronology of catastrophic floods in this region.</p><p>The recovery of historical meteorological data from libraries and archives and the subsequent digitization to obtain readable-machine version has been a main task in our research. Meteorological data from different sources (manuscripts, books, newspapers, etc.) and eight different locations in Extremadura have been recovered and digitized. The oldest data were read in 1824 (Fernández-Fernández et al., 2014). Other important meteorological series can be highlighted as the actinometric measurements in Cáceres for the period 1913-1920 (Bravo-Paredes et al., 2019).</p><p>“Pro-pluvia” rogations were celebrated during dry conditions to ask God for rain. In our case, 35 “pro-pluvia” rogations were retrieved for the period 1824-1931 from different locations in Extremadura. The winter climate of this region is strongly dominated by the North Atlantic Oscillation (NAO) and, therefore, these pro-pluvia rogations were associated to the NAO index to analyze this relationship. The results of our analysis show that the rogation ceremonies in Extremadura can be considered a good proxy for the NAO index. Also, it is important to know the magnitude and the impact of the catastrophic floods occurred in Extremadura. In total, 40 floods occurred in Badajoz were recovered from different documentary sources for the period 1545-1989.</p><p>All these research efforts will allow for a better understanding of the past climate in the region of Extremadura, where such studies have been very scarce.</p><p>References</p><p>Bravo-Paredes, N. et al. (2019) “Analysis of actinometric measurements under different sky conditions in Cáceres (Spain) for the period 1913-1920” Tellus B 71, 1663597. DOI: 10.1080/16000889.2019.1663597</p><p>Fernández-Fernández, M.I. et al. (2014) "The climate of Zafra from 1750 to 1840: History and description of weather observations" Climatic Change 126, 107–118. (doi: 10.1007/s10584-014-1201-5)</p>

scholarly journals Pro-Pluvia Rogation Ceremonies in Extremadura (Spain): Are They a Good Proxy of Winter NAO?

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 282 ◽  
Author(s):  
Nieves Bravo-Paredes ◽  
María Cruz Gallego ◽  
Fernando Domínguez-Castro ◽  
José Agustín García ◽  
José Manuel Vaquero
Keyword(s):  
North Atlantic ◽  
Confidence Level ◽  
Documentary Sources ◽  
The North ◽  
Nao Index ◽  
Dry Conditions ◽  
The North Atlantic ◽  
Good Proxy ◽  
The North Atlantic Oscillation ◽  
The Relationship

Rogation ceremonies are religious requests to God. Pro-pluvia rogations were celebrated during dry conditions to ask God for rain. In this work, we have recovered 37 pro-pluvia rogations from 14 documentary sources (e.g.,: ecclesiastical manuscripts, books, and different magazines and newspapers). All of the rogations were celebrated in Extremadura region (interior of southwest of Spain) during the period 1824–1931. Climate of Extremadura is strongly dominated by the North Atlantic Oscillation (NAO). Therefore, pro-pluvia rogations have been associated to the NAO index and the relationship between them has been analyzed. The most relevant results are found in the relationship between pro-pluvia rogations in month n and the positive values of the NAO index for months n-1 and n-2, being statistically significant at 95% confidence level. Thus, the results evidence that the rogation ceremonies of Extremadura are a good proxy for the NAO index.

scholarly journals Heavy Rainfall and Landslide Event in January 1831 at the Pedregoso Mountains (Cabeza Del Buey, SW Spain)

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 544 ◽  
Author(s):  
Juan Pedro García-Garrido ◽  
María Cruz Gallego ◽  
Teodoro Palacios ◽  
Ricardo M. Trigo ◽  
José Manuel Vaquero
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Meteorological Data ◽  
Triggering Mechanism ◽  
Sw Spain ◽  
The North ◽  
Nao Index ◽  
Landslide Event ◽  
High Precipitation ◽  
The North Atlantic Oscillation

In this work, a landslide event that took place on January 1831 at the Pedregoso Mountains, Cabeza del Buey, SW Spain, is described. This landslide had not been documented to date and was only described in the local press. This event involved an estimated amount of dislodged material in the order of 104 m3. The amount of meteorological data is very scarce as the event occurred before the setting up of the national meteorological service in Spain. However, data from the relatively near location of SW Iberia suggest that the landslide was preceded by a prolonged period of unusually high precipitation totals and that this intense wet period is compatible with the large-scale atmospheric configuration in the winter of 1829–1830. In fact, the North Atlantic Oscillation (NAO) index for that winter achieved one of the most negative values observed in the bicentennial period spanning 1821 to 2019. This multidisciplinary work represents the first attempt to report and describe the main triggering mechanism for an historical landslide in the Extremadura region that is similar to other great historical landslides which have already been documented for other locations in Spain.

scholarly journals Reconstructing winter climate anomalies in the Euro-Atlantic sector using circulation patterns

2021 ◽  
Vol 2 (3) ◽  
pp. 777-794
Author(s):  
Erica Madonna ◽  
David S. Battisti ◽  
Camille Li ◽  
Rachel H. White
Keyword(s):  
Region Of Interest ◽  
Zonal Flow ◽  
Winter Climate ◽  
Large Variability ◽  
Atlantic Sector ◽  
Climate Anomalies ◽  
The North ◽  
Nao Index ◽  
Classification Pattern ◽  
The North Atlantic Oscillation

Abstract. The efficacy of Euro-Atlantic circulation regimes for estimating wintertime climate anomalies (precipitation and surface temperature) over Europe is assessed. A comparison of seasonal climate reconstructions from two different regime frameworks (cluster analysis of the low-level zonal flow, and traditional blocking indices) is presented and contrasted with seasonal reconstructions using the North Atlantic Oscillation (NAO) index. The reconstructions are quantitatively evaluated using correlations and the coefficient of efficiency, accounting for misfit in phase and amplitude. The skill of the various classifications in reconstructing seasonal anomalies depends on the variable and region of interest. The jet and blocking regimes are found to capture more spatial structure in seasonal precipitation anomalies over Europe than the NAO, with the jet framework showing generally better skill relative to the blocking indices. The reconstructions of temperature anomalies have lower skill than those for precipitation, with the best results for temperature obtained by the NAO for high-latitude and by the blocking framework for southern Europe. All methods underestimate the magnitude of seasonal anomalies due to the large variability in precipitation and temperature within each classification pattern.

scholarly journals Reconstructing winter climate anomalies in the Euro-Atlantic sector using circulation patterns

2021 ◽  
Author(s):  
Erica Madonna ◽  
David S. Battisti ◽  
Camille Li ◽  
Rachel H. White
Keyword(s):  
Zonal Flow ◽  
Winter Climate ◽  
Atlantic Sector ◽  
Climate Anomalies ◽  
The North ◽  
Nao Index ◽  
Climate Reconstructions ◽  
Circulation Patterns ◽  
Precipitation Anomalies ◽  
The North Atlantic Oscillation

Abstract. The efficacy of Euro-Atlantic circulation regimes for estimating wintertime climate anomalies (precipitation and surface temperature) over Europe is assessed. A comparison of seasonal climate reconstructions from two different regime frameworks (cluster analysis of the low-level zonal flow, and traditional blocking indices) is presented and contrasted with seasonal reconstructions using the North Atlantic Oscillation (NAO) index. The reconstructions are quantitatively evaluated using correlations and the coefficient of efficiency, accounting for misfit in phase and amplitude. While all methods show skill in reproducing wintertime precipitation and temperature variability, they underestimate the magnitude of seasonal anomalies by a factor of two. The regimes are found to capture more spatial structure in seasonal precipitation anomalies over Europe than the NAO, with the jet framework showing generally better skill relative to the blocking indices. The reconstructions of temperature anomalies have lower skill than those for precipitation, with the best results for temperature obtained by the NAO for high-latitude and by the blocking framework for southern Europe.

scholarly journals The Role of the North Atlantic Oscillation in Shaping Regional-Scale Peak Seasonal Precipitation across the Indian Subcontinent

2011 ◽  
Vol 15 (2) ◽  
pp. 1-13 ◽  
Author(s):  
Shouraseni Sen Roy
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Indian Subcontinent ◽  
Regional Level ◽  
The North ◽  
Nao Index ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The Impact

Abstract The present study focuses on the impact of the North Atlantic Oscillation (NAO) in shaping the regional-level precipitation during the peak months of the two main rainy seasons over the Indian subcontinent. Monthly precipitation data from 1871 to 2005 were collected for 30 homogenous regions across the subcontinent. Regression analysis was used to analyze the strength of the relationship between NAO on regional-level precipitation patterns. The results of the study showed distinct spatial variations in the response of regional-level rainfall to the monthly NAO index. There were greater variations in the strength of the regression coefficients for peak monsoon rainfall (PMR) compared to the peak winter rainfall (PWR) season. During the latter half of the year, the association between PMR and the NAO index was predominantly negative. In general, the role of NAO was more pronounced across most of the regions in the peninsular India.

scholarly journals Shallow and deep landslides induced by rainfall in the Lisbon region (Portugal): assessment of relationships with the North Atlantic Oscillation

2005 ◽  
Vol 5 (3) ◽  
pp. 331-344 ◽  
Author(s):  
J. L. Zêzere ◽  
R. M. Trigo ◽  
I. F. Trigo
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Winter Precipitation ◽  
Rain Gauge ◽  
Precipitation Regime ◽  
The North ◽  
Nao Index ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The Impact

Abstract. The aim of this study is to assess the impact of the North Atlantic Oscillation (NAO) on both the winter precipitation and the temporal occurrence of different landslide types in Portugal. The analysis is applied to five sample areas located just north of Lisbon, the capital of Portugal. These sites are particularly relevant because actual dates of most of the recent landslide events are known but also because the landslides occurred in a suburban area with growing urbanization pressure. Results show that the large inter-annual variability of winter precipitation observed in western Iberia, i.e. Portugal and parts of Spain, is largely modulated by the NAO mode. In particular, precipitation falling in Portugal between November and March presents a correlation coefficient of R=–0.66 with the NAO index. Precipitation distribution for the reference rain gauge in the study area reveals that the probability of a wet month to occur is much higher for low NAO index composites than for the corresponding high NAO index composite. It is shown that this control, exerted by NAO on the precipitation regime, is related to corresponding changes in the associated activity of North-Atlantic storm tracks that affect the western Iberia. Landslide activity in the study area is related to both intense, short duration precipitation events (1–15 days) and long-lasting rainfall episodes (1–3 months). The former events trigger shallow translational slides while the later episodes are usually associated with deeper and larger slope movements. This second group of landslides is shown to be statistically associated with the 3-month average of the NAO index.

Intermittency of Arctic-midlatitude teleconnections: the stratospheric pathway between autumn sea ice and the winter NAO

2020 ◽  
Author(s):  
Peter Yu Feng Siew ◽  
Camille Li ◽  
Stefan Sobolowski ◽  
Martin King
Keyword(s):  
Sea Ice ◽  
Causal Effect ◽  
Signal To Noise Ratio ◽  
Kara Sea ◽  
Arctic Sea Ice ◽  
Winter Climate ◽  
The North ◽  
Nao Index ◽  
Ice Conditions ◽  
The North Atlantic Oscillation

<p>An observed relationship linking Arctic sea ice conditions in autumn to the North Atlantic Oscillation (NAO) index the following winter has potential relevance for seasonal predictions of European and North American climate. The physical pathway most often invoked to explain this particular teleconnection passes through the stratosphere. A Causal Effect Networks (CEN) approach is used to explore this stratospheric pathway between late autumn Barents-Kara sea ice and the February NAO, focusing on its seasonal evolution, timescale-dependence, and robustness. This pathway is statistically detectable in the satellite period, explaining 26% of the interannual variability in the February NAO. However, a bootstrap-resampling test reveals that the pathway is highly intermittent: the whole pathway emerges in only 15% of the bootstrapped samples. The intermittent nature of the pathway is consistent with the weak signal-to-noise ratio of the atmospheric response in the sea ice perturbation experiments, and suggests that a background state is important in determining whether the pathway is active. Higher frequency synoptic interactions between Barents-Kara sea ice and sea level pressure over Urals potentially interfere with the stratospheric pathway. Such interference likely reduces the potential for using the ice-NAO relationship for predicting midlatitude winter climate. This study helps quantify the robustness of linkages within the stratospheric pathway, and provides insight into which linkages are most subject to sampling issues within the relatively short observational record.</p>

scholarly journals Influência da Oscilação do Atlântico Norte no clima do continente europeu e no caudal dos rios ibéricos atlânticos

Finisterra ◽  
2012 ◽  
Vol 37 (73) ◽  
Author(s):  
Ricardo Trigo ◽  
Timothy Osborn ◽  
João Corte-Real
Keyword(s):  
North Atlantic ◽  
River Flow ◽  
Precipitable Water ◽  
Mean Flow ◽  
The North ◽  
Nao Index ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The Impact ◽  
Iberian Rivers

THE IMPACT OF THE NORTH ATLANTIC OSCILLATION ON THE EUROPEAN CLIMATE AND RIVER FLOW OF THREE MAJOR IBERIAN RIVERS – The North Atlantic Oscillation (NAO) is the most dominant mode of atmospheric circulation variability over the entire Northern Hemisphere (NH) and has recently been shown to be related to climate over large regions of the NH, in particular, over the European and North American continents. Here, a multivariable analysis of the influence ofthe NAO on the climate of the North Atlantic and European sectors is presented using the 40 year (1958-97) reanalysis data set from National Centres for Environmental Prediction. Using high and low NAO index composites, anomaly fields of climate variables are then interpreted based on physical mechanisms associated with the anomalous mean flow (characterised by the surface wind field) and theanomalous eddy activity (characterised by the surface vorticity and the 500hPa storm track fields). It is shown that NAO-related temperature patterns are mainly controlled by the advection of heat by the anomalous mean flow. However, asymmetries between minimum and maximum temperatures, and more significantly, between positive and negative phases of NAO imply the importance of a different mechanism, namely the modulation of short wave and long wave radiation by cloud cover variations associated with the NAO. Furthermore, NAO influence over two different precipitation-related variables, namely, precipitation rate and precipitable water display different patterns. Precipitable water is shown to be strongly related to the corresponding anomaly fields of temperature while precipitation rate appears to be controlled by the surface vorticity field and associated strength of the tropospheric synoptic activity. Finally, we have assessed the impact of the NAO on winter river flow regimes for several different Portuguese rivers, including the three main international Iberian rivers, the Douro (north), the Tagus (centre) and the Guadiana (south). Results show that the large inter-annual variability of flow of these three rivers is largely modulated by the NAO. Such modulation, associated with the recent positive trend of the NAO index, might implicate a significant decrease of the available flow. This reduction can representan important hazard for the Portuguese economy due to its negative impact in agricultural yield and hydroelectric power production.

scholarly journals The Impact of the North Atlantic Oscillation on Climate through Its Influence on the Atlantic Meridional Overturning Circulation

2016 ◽  
Vol 29 (3) ◽  
pp. 941-962 ◽  
Author(s):  
Thomas L. Delworth ◽  
Fanrong Zeng
Keyword(s):  
North Atlantic ◽  
Time Scale ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
The North ◽  
Hemispheric Temperature ◽  
Meridional Overturning ◽  
The North Atlantic Oscillation ◽  
The Impact ◽  
Model Ocean

Abstract The impact of the North Atlantic Oscillation (NAO) on the Atlantic meridional overturning circulation (AMOC) and large-scale climate is assessed using simulations with three different climate models. Perturbation experiments are conducted in which a pattern of anomalous heat flux corresponding to the NAO is added to the model ocean. Differences between the perturbation experiments and a control illustrate how the model ocean and climate system respond to the NAO. A positive phase of the NAO strengthens the AMOC by extracting heat from the subpolar gyre, thereby increasing deep-water formation, horizontal density gradients, and the AMOC. The flux forcings have the spatial structure of the observed NAO, but the amplitude of the forcing varies in time with distinct periods varying from 2 to 100 yr. The response of the AMOC to NAO variations is small at short time scales but increases up to the dominant time scale of internal AMOC variability (20–30 yr for the models used). The amplitude of the AMOC response, as well as associated oceanic heat transport, is approximately constant as the time scale of the forcing is increased further. In contrast, the response of other properties, such as hemispheric temperature or Arctic sea ice, continues to increase as the time scale of the forcing becomes progressively longer. The larger response is associated with the time integral of the anomalous oceanic heat transport at longer time scales, combined with an increased impact of radiative feedback processes. It is shown that NAO fluctuations, similar in amplitude to those observed over the last century, can modulate hemispheric temperature by several tenths of a degree.

scholarly journals A Regime View of the North Atlantic Oscillation and Its Response to Anthropogenic Forcing

2010 ◽  
Vol 23 (6) ◽  
pp. 1291-1307 ◽  
Author(s):  
Tim Woollings ◽  
Abdel Hannachi ◽  
Brian Hoskins ◽  
Andrew Turner
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Anthropogenic Forcing ◽  
The Third ◽  
The North ◽  
Nao Index ◽  
Future Behavior ◽  
Real Change ◽  
The North Atlantic Oscillation

Abstract The distribution of the daily wintertime North Atlantic Oscillation (NAO) index in the 40-yr ECMWF Re-Analysis (ERA-40) is significantly negatively skewed. Dynamical and statistical analyses both suggest that this skewness reflects the presence of two distinct regimes—referred to as “Greenland blocking” and “subpolar jet.” Changes in both the relative occurrence and in the structure of the regimes are shown to contribute to the long-term NAO trend over the ERA-40 period. This is contrasted with the simulation of the NAO in 100-yr control and doubled CO2 integrations of the third climate configuration of the Met Office Unified Model (HadCM3). The model has clear deficiencies in its simulation of the NAO in the control run, so its predictions of future behavior must be treated with caution. However, the subpolar jet regime does become more dominant under anthropogenic forcing and, while this change is small it is clearly statistically significant and does represent a real change in the nature of NAO variability in the model.

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