scholarly journals The Climate of the Common Era off the Iberian Peninsula

2017 ◽  
Author(s):  
Fátima Abrantes ◽  
Teresa Rodrigues ◽  
Marta Rufino ◽  
Emília Salgueiro ◽  
Dulce Oliveira ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Ice Age ◽  
Higher Plant ◽  
European Continent ◽  
Climate Conditions ◽  
Shelf Sediment ◽  
South Portugal

Abstract. The Iberian Peninsula, at North Atlantic mid-latitude and the western extreme of the European continent, is a relevant area for climate reconstructions. This work provides multi-proxy records measured in 7 inner-shelf sediment sequences from 5 sites located between South Portugal (Algarve) and Northwest Spain (Galiza) (36 to 42º N) and targets a regional reconstruction of climate variability during the last 2000 yr. Alkenone derived Sea Surface Temperature (SST) reconstructions were compared to on-land precipitation given by higher plant n-alkanes and pollen data, to assess the relationship between hydroclimate (drought and/or precipitation) and oceanic SST. The SST records reveal a long-term scale cooling (±1 ºC/2000 yr) that ends at the beginning of the 20th century at all sites. This cooling is a follow up of the cooling process started after the Holocene optimum and driven by a decrease in summer insolation in the Northern Hemisphere. A multi-decadal/ centennial variability is detected within this long-term cooling in convergence with other records from Spain, Europe and the Northern Hemisphere. Warm SST conditions prevailed throughout the first 1300 yr, encompassing the Roman Period (RP), the Dark Ages (DA) and the Medieval Warm Period (MWP). A cooling initiated at 1300 CE, led to 4 centuries of ±1 ºC colder mean SSTs contemporary with the Little Ice Age (LIA). The transition towards the Industrial Era starts by 1800 CE with a SST rise to pre-LIA levels. Particular climate conditions have been detected in Western Iberian margin records and reveal two distinct phases within the MWP and a two-step SST increase towards the Industrial Era. The intense precipitation/flooding and warm winters but cooler intermediate seasons (spring and fall) observed for the early MWP imply the interplay of internal oceanic variability with the three atmospheric circulation modes, North Atlantic Oscillation (NAO), East Atlantic (EA) and Sandinavia (SCAND) in a positive phase. The late MWP, marked by drier and cooler winters and warmer intermediate seasons calls for a change in sign of the SCAND. A stronger mark of oceanic influences on Western Iberian Peninsula starts with the transition to the Industrial Era.

scholarly journals Historical Climate off the Atlantic Iberian Peninsula

2017 ◽  
Author(s):  
Fátima Abrantes ◽  
Teresa Rodrigues ◽  
Marta Rufino ◽  
Emília Salgueiro ◽  
Dulce Oliveira ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Sediment Cores ◽  
Ice Age ◽  
Regional Variability ◽  
Higher Plant ◽  
European Continent ◽  
Sst Variability ◽  
Shelf Sediment ◽  
South Portugal

Abstract. The Iberian Peninsula, at North Atlantic mid-latitude and the western extreme of the European continent, is a key point for climate reconstructions. This work provides multi-proxy records measured in 8 inner-shelf sediment cores from 5 sites located between South Portugal (Algarve) and Northwest Spain (Galiza) (36 to 41º N) and target a regional reconstruction of climate variability during the Historic period (last 2 ky). The SST records reveal a long-term scale cooling (±1 ºC/2 ky) that ends at the beginning of the 20th century at all latitudes. This cooling is a follow up of the cooling process that started in the early Holocene driven by a decrease in summer insolation in the Northern Hemisphere. Within this long term SST variability multi-decadal/centennial scale variability is detected along Iberia. The different latitudinal SST reconstructions jointly with a determined regional SST stack were compared to on-land precipitation from higher plant n-alkanes and pollen data, to assess the relationship between hydroclimate (drought and/or precipitation) and SST. Regional variability is overall in consonance with NE Spain, and other European and north Hemisphere reconstructions. Warm conditions prevailed throughout 1300 yr, encompassing the Roman Period (RP), the Dark Ages (DA) and the Medieval Warm Period (MWP). The initial cooling at 1300 CE leads to 4 centuries of ±1 ºC colder mean SSTs contemporaneous with the Little Ice Age (LIA). The transition towards the Industrial Era starts by 1800 CE with a rise to pre-LIA SSTs. Climate specificities have been detected in western Iberian margin records and reveal the existence of two distinct phases within the MWP and a two-step SST increase towards the Industrial Era. The intense precipitation/flooding and warm winters but cooler intermediate seasons observed for the early MWP imply the interplay of internal oceanic variability with the three known atmospheric circulation modes, AMO, EA and SCAND in a positive phase. The late MWP, typified by drier and cooler winters and warmer intermediate seasons calls for a change in sign of the SCAND. A stronger mark of oceanic influences on western Iberian Peninsula (IP) starts with the transition to the Industrial Era.

scholarly journals The Little Ice Age, the climatic background of present-day warming in Europe

2018 ◽  
Vol 44 (1) ◽  
pp. 7 ◽  
Author(s):  
M. Oliva
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Future Research ◽  
Climate Regime ◽  
European Continent ◽  
Economic Implications ◽  
Climate Conditions ◽  
Wide Range ◽  
Show Evidence ◽  
Spatio Temporal

The Little Ice Age (LIA) constitutes the coldest period of the last millennia in Europe. A wide range of natural and historical records show evidence of colder climate conditions between the 14th and 19th centuries, together with a higher frequency of extreme hydroclimatic events. During these centuries, temperatures and precipitations showed different spatio-temporal patterns across Europe. This Special Issue includes eleven scientific works focusing on the climate regime, environmental dynamics as well as socio-economic implications of the LIA in Europe. Besides, this paper also identifies key guidelines for future research on the LIA causes and its consequences on environmental systems in the European continent.

Near-surface wind speeds in ERA5: Climatology, decadal variability and long-term trends

2021 ◽  
Author(s):  
Terhi K. Laurila ◽  
Victoria A. Sinclair ◽  
Hilppa Gregow
Keyword(s):  
Iberian Peninsula ◽  
North Atlantic ◽  
Decadal Variability ◽  
Surface Wind ◽  
Northern Europe ◽  
Near Surface ◽  
Wind Speeds ◽  
The North ◽  
The North Atlantic

<p>The knowledge of long-term climate and variability of near-surface wind speeds is essential and widely used among meteorologists, climate scientists and in industries such as wind energy and forestry. The new high-resolution ERA5 reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF) will likely be used as a reference in future climate projections and in many wind-related applications. Hence, it is important to know what is the mean climate and variability of wind speeds in ERA5.</p><p>We present the monthly 10-m wind speed climate and decadal variability in the North Atlantic and Europe during the 40-year period (1979-2018) based on ERA5. In addition, we examine temporal time series and possible trends in three locations: the central North Atlantic, Finland and Iberian Peninsula. Moreover, we investigate what are the physical reasons for the decadal changes in 10-m wind speeds.</p><p>The 40-year mean and the 98th percentile wind speeds show a distinct contrast between land and sea with the strongest winds over the ocean and a seasonal variation with the strongest winds during winter time. The winds have the highest values and variabilities associated with storm tracks and local wind phenomena such as the mistral. To investigate the extremeness of the winds, we defined an extreme find factor (EWF) which is the ratio between the 98th percentile and mean wind speeds. The EWF is higher in southern Europe than in northern Europe during all months. Mostly no statistically significant linear trends of 10-m wind speeds were found in the 40-year period in the three locations and the annual and decadal variability was large.</p><p>The windiest decade in northern Europe was the 1990s and in southern Europe the 1980s and 2010s. The decadal changes in 10-m wind speeds were largely explained by the position of the jet stream and storm tracks and the strength of the north-south pressure gradient over the North Atlantic. In addition, we investigated the correlation between the North Atlantic Oscillation (NAO) and the Atlantic Multi-decadal Oscillation (AMO) in the three locations. The NAO has a positive correlation in the central North Atlantic and Finland and a negative correlation in Iberian Peninsula. The AMO correlates moderately with the winds in the central North Atlantic but no correlation was found in Finland or the Iberian Peninsula. Overall, our study highlights that rather than just using long-term linear trends in wind speeds it is more informative to consider inter-annual or decadal variability.</p>

scholarly journals Twenty Years of Atmospheric 14Co2 Observations At Schauinsland Station, Germany

Radiocarbon ◽  
1997 ◽  
Vol 39 (2) ◽  
pp. 205-218 ◽  
Author(s):  
Ingeborg Levin ◽  
Bernd Kromer
Keyword(s):  
Northern Hemisphere ◽  
Seasonal Variations ◽  
Fossil Fuel ◽  
Data Sets ◽  
Black Forest ◽  
European Continent ◽  
Northern Latitudes ◽  
Single Exponential Function ◽  
Single Exponential

We present and discuss quasi-continuous long-term 14CO2 observations from the continental background station Schauinsland (48°N, 8°E, 1205 m asl, Black Forest, southern Germany). The observed steady decline of atmospheric 14CO2 from 1977 to 1996 can be described by a single exponential function with an e-folding time of (16.3 ± 0.2) yr. Summer means (May to August) in atmospheric 14CO2 at Schauinsland compare within Δ14C = ±4‰ with measurements made on individual rings from a tree grown in the near vicinity of the Schauinsland site. Both data sets are slightly depleted by up to 5‰ if compared to maritime background measurements of atmospheric 14CO2 made at Izaña, Tenerife. This is due to the influence of fossil fuel CO2 emissions over the European continent as well as generally in mid latitudes of the Northern Hemisphere. δ13C analyses from the Schauinsland samples show mean seasonal variations with an amplitude of ±0.4‰, caused by atmosphere-biosphere exchange, and a mean decrease from 1977 to 1996 of δ13C = −0.017‰ yr−1. This trend is mainly due to an increasing quantity of fossil fuel CO2 in the atmosphere, depleted in 13C/12C ratio, and compares well to trends measured at other stations in mid-to-high northern latitudes.

North Atlantic atmospheric circulation and surface wind in the Northeast of the Iberian Peninsula: uncertainty and long term downscaled variability

2011 ◽  
Vol 38 (1-2) ◽  
pp. 141-160 ◽  
Author(s):  
E. García-Bustamante ◽  
J. F. González-Rouco ◽  
J. Navarro ◽  
E. Xoplaki ◽  
P. A. Jiménez ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Surface Wind

Global Ice-Sheet System Interlocked by Sea Level

1986 ◽  
Vol 26 (1) ◽  
pp. 3-26 ◽  
Author(s):  
George H. Denton ◽  
Terence J. Hughes ◽  
Wibjörn Karlén
Keyword(s):  
Carbon Dioxide ◽  
Sea Level ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
High Frequency ◽  
Atmospheric Carbon Dioxide ◽  
Ice Sheet ◽  
Ice Age ◽  
Atmospheric Carbon

Denton and Hughes (1983, Quaternary Research 20, 125–144) postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during late Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75°N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet, thus fitting the concept of a globally interlocked ice-sheet system. But recent atmospheric modeling results (Manabe and Broccoli, 1985, Journal of Geophysical Research 90, 2167–2190) suggest that factors other than areal changes of the grounded Antarctic Ice Sheet strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate (Shackleton and Pisias, 1985, Atmospheric carbon dioxide, orbital forcing, and climate. In “The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present” (E. T. Sundquest and W. S. Broecker, Eds.), pp. 303–318. Geophysical Monograph 32, American Geophysical Union, Washington, D.C.), but another potential influence was high-frequency climatic oscillations (2500 yr). It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm high-frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 14C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide (W. S. Broecker, D. M. Peteet, and D. Rind, 1985, Nature (London) 315, 21–26). Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

scholarly journals Considerações acerca do arrefecimento Plistocénico em Portugal

Finisterra ◽  
2012 ◽  
Vol 35 (70) ◽  
Author(s):  
António Brum Ferreira
Keyword(s):  
Iberian Peninsula ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Western Europe ◽  
Climatic Conditions ◽  
The North ◽  
Last Glaciation ◽  
Summer Temperatures ◽  
The North Atlantic

NOTE ON THE PLEISTOCENE COOLING IN PORTUGAL – Prevailing conditionsin the North Atlantic and Western Europe during the Maximum Cooling of the Last Glaciation can be deduced from the Climap Project (1976) results and from the Atlas of Paleoclimates and Paleoenvironments of the Northern Hemisphere (FRENZEL et al., 1992). Taking into account this framework of extreme climatic conditions and the nature of the glacial and periglacial relict phenomena in the Iberian Peninsula, an attempt is made to evaluate the degree of cooling in Portugal during the Gerês and Estrela glaciations. A drop of about 10º C in summer temperatures is suggested.

scholarly journals Flow dependence of wintertime subseasonal prediction skill over Europe

2021 ◽  
Author(s):  
Constantin Ardilouze ◽  
Damien Specq ◽  
Lauriane Batté ◽  
Christophe Cassou
Keyword(s):  
Northern Hemisphere ◽  
North Atlantic ◽  
Scientific Community ◽  
A Priori ◽  
Climate Simulation ◽  
Sea Level Pressure ◽  
Nao Index ◽  
Flow Dependence ◽  
Similar Temperature

Abstract. Issuing skillful forecasts beyond the typical horizon of weather predictability remains a challenge actively addressed by the scientific community. This study evaluates winter subseasonal reforecasts delivered by the CNRM and ECMWF dynamical systems and identifies that the level of skill for predicting temperature in Europe varies fairly consistently in both systems. In particular, forecasts initialized during positive North-Atlantic Oscillation (NAO) phases tend to be more skillful over Europe at week 3 in both systems. Composite analyses performed in an atmospheric reanalysis, a long-term climate simulation and both forecast systems unveil very similar temperature and sea-level pressure patterns three weeks after NAO conditions. Furthermore, regressing these fields onto the 3-week prior NAO index in a reanalysis shows consistent patterns over Europe but also other regions of the northern hemisphere extratropics, thereby suggesting a lagged teleconnection, either related to the persistence or recurrence of the postive and negative phases of the NAO. This teleconnection, conditionned to the intensity of the initial NAO phase, is well captured by forecast systems. As a result, it is a key mechanism for determining a priori confidence in the skill of wintertime subseasonal forecasts over Europe as well as others parts of the northern hemisphere.

scholarly journals Continental atmospheric circulation over Europe during the Little Ice Age inferred from grape harvest dates

2011 ◽  
Vol 7 (5) ◽  
pp. 3023-3048 ◽  
Author(s):  
P. Yiou ◽  
I. García de Cortázar-Atauri ◽  
I. Chuine ◽  
V. Daux ◽  
E. Garnier ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Data Sets ◽  
Atmospheric Flow ◽  
Climate Conditions ◽  
The North ◽  
Harvest Dates ◽  
The 19Th Century

Abstract. Estimates of climate conditions before the 19th century are based on proxy data reconstructions or sparse meteorological measurements. The reconstruction of the atmospheric circulation that prevailed during the European Little Ice Age (~1500–1850) has fostered many efforts. This study illustrates a methodology combining historical proxies and modern data sets to obtain detailed information on the atmospheric circulation that prevailed over the North Atlantic region during the Little Ice Age. We use reconstructions of temperature gradients over France based on grape harvest dates to infer the atmospheric circulation. We find that blocking situations were more likely in summer, inducing a continental atmospheric flow. This study advocates that the reconstructions of the past atmospheric circulation should take this regime into account.

scholarly journals The climate of the Common Era off the Iberian Peninsula

2017 ◽  
Vol 13 (12) ◽  
pp. 1901-1918 ◽  
Author(s):  
Fátima Abrantes ◽  
Teresa Rodrigues ◽  
Marta Rufino ◽  
Emília Salgueiro ◽  
Dulce Oliveira ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
20Th Century ◽  
Northern Hemisphere ◽  
Climate Warming ◽  
North Atlantic ◽  
Positive Phase ◽  
Future Climate Change ◽  
Fall Season ◽  
Nw Iberia

Abstract. The Mediterranean region is a climate hot spot, sensitive not only to global warming but also to water availability. In this work we document major temperature and precipitation changes in the Iberian Peninsula and margin during the last 2000 years and propose an interplay of the North Atlantic internal variability with the three atmospheric circulation modes (ACMs), (North Atlantic Oscillation (NAO), east atlantic (EA) and Scandinavia (SCAND)) to explain the detected climate variability. We present reconstructions of sea surface temperature (SST derived from alkenones) and on-land precipitation (estimated from higher plant n-alkanes and pollen data) in sedimentary sequences recovered along the Iberian Margin between the south of Portugal (Algarve) and the northwest of Spain (Galiza) (36 to 42° N). A clear long-term cooling trend, from 0 CE to the beginning of the 20th century, emerges in all SST records and is considered to be a reflection of the decrease in the Northern Hemisphere summer insolation that began after the Holocene optimum. Multi-decadal/centennial SST variability follows other records from Spain, Europe and the Northern Hemisphere. Warm SSTs throughout the first 1300 years encompass the Roman period (RP), the Dark Ages (DA) and the Medieval Climate Anomaly (MCA). A cooling initiated at 1300 CE leads to 4 centuries of colder SSTs contemporary with the Little Ice Age (LIA), while a climate warming at 1800 CE marks the beginning of the modern/Industrial Era. Novel results include two distinct phases in the MCA: an early period (900–1100 years) characterized by intense precipitation/flooding and warm winters but a cooler spring–fall season attributed to the interplay of internal oceanic variability with a positive phase in the three modes of atmospheric circulation (NAO, EA and SCAND). The late MCA is marked by cooler and relatively drier winters and a warmer spring–fall season consistent with a shift to a negative mode of the SCAND. The Industrial Era reveals a clear difference between the NW Iberia and the Algarve records. While off NW Iberia variability is low, the Algarve shows large-amplitude decadal variability with an inverse relationship between SST and river input. Such conditions suggest a shift in the EA mode, from negative between 1900 and 1970 CE to positive after 1970, while NAO and SCAND remain in a positive phase. The particularly noticeable rise in SST at the Algarve site by the mid-20th century (±1970), provides evidence for a regional response to the ongoing climate warming. The reported findings have implications for decadal-scale predictions of future climate change in the Iberian Peninsula.

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