scholarly journals Enhanced western Mediterranean rainfall during past interglacials driven by North Atlantic pressure changes

2019 ◽  
Author(s):  
Yama Dixit ◽  
Samuel Toucanne ◽  
Juan M. Lora ◽  
Christophe Fontanier ◽  
Virgil Pasquier ◽  
...  
Keyword(s):  
North Atlantic ◽  
Western Mediterranean ◽  
Sea Surface ◽  
Tyrrhenian Sea ◽  
Winter Rainfall ◽  
The Past ◽  
The North ◽  
Hydrological Changes ◽  
The North Atlantic ◽  
The Mediterranean

Abstract. There is increasing concern with anthropogenic greenhouse gas emissions that ocean warming, in concert with summer and winter precipitation changes, will induce anoxia in multiple ocean basins. In particular the Mediterranean Sea is susceptible to severe hydrological changes. Mediterranean hydroclimate is controlled primarily by two phenomena – the latitudinal migration of the Inter-Tropical Convergence Zone and the North Atlantic climatic processes. While the former brings about the African summer monsoon rainfall the latter drives the wintertime storm tracks into the western Mediterranean. Although the hydrological changes in the eastern Mediterranean are quite well constrained, evidence of past changes in temperature and rainfall in the western Mediterranean across the past interglacials is relatively scarce. In this study, we use trace element and stable isotope composition of planktonic foraminifera from a sediment core off Corsica at the mouth of Golo river in the western Mediterranean to reconstruct variations in sea surface temperature (SST) and sea surface salinities (SSS) during the Holocene and warm periods of the past two interglacials. Our data suggest that the warm periods of the last interglacials were characterised by high river discharge and lower SSS in the northern Tyrrhenian Sea, suggesting increased winter rainfall. We find evidence that enhanced winter rainfall during periods of precession minima and high seasonality across interglacials coincide with changes in the respective eccentricity maxima suggesting a causal link. Our model simulations for representative orbital configurations such as the mid-Holocene support increased south-westerly moisture transport into the western Mediterranean originating from the North Atlantic. We suggest that these hydrologic changes in the western and the northern Mediterranean borderlands were a contributing factor to basin-wide anoxia in the past. Our findings offer new insights into the cause and impact of winter rainfall changes in the Mediterranean during past warm periods.

Observational analysis of Mediterranean decadal hydroclimate variability: role of Atlantic-Mediterranean sea surface temperatures

2020 ◽  
Author(s):  
Roberto Suarez-Moreno ◽  
Richard Seager ◽  
Yochanan Kushnir
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Mediterranean Region ◽  
Sea Surface ◽  
Wet Season ◽  
The North ◽  
Hydroclimate Variability ◽  
The North Atlantic ◽  
The Mediterranean

<p>The Mediterranean region is a semi-arid climate zone, subject to droughts, where water resources are scarce and observational data and climate models suggest a tendency towards greater aridification. Moreover, the Mediterranean region is an area of social and political instability and, in the Middle East, open warfare, which might be further stressed by climate change. The North Atlantic Oscillation (NAO) is the dominant mode of winter climate variability in the North Atlantic sector, playing the leading role in driving Mediterranean hydroclimate variability from seasonal to multidecadal timescales, whereas the influence of sea surface temperatures (SSTs) remains unclear. Nevertheless, the mechanism underlying the NAO is still under debate, and the possibility for coupled ocean-atmosphere decadal interactions, for which several mechanisms have been proposed, would support the role of SST. Based on observations and reanalysis, we conduct a statistical-observational analysis to explore the decadal drivers of Mediterranean hydroclimate variability for the winter half-year (October-to-March) wet season. Our results put forward the uneven intraseasonal influence of the decadal NAO, being the leading driver during the winter peak season (December-to-March), while decadal Atlantic-Mediterranean SST variability exhibit a consistent link for the first months of the wet season (October-to-January). These results emphasize the need to further explore the ocean-atmosphere feedback mechanisms and their possible modulations under climate change. Understanding these mechanisms is essential to improve predictability of hydroclimate in the Mediterranean region, leading to adaptation strategies that mitigate the effect of climate change on the vulnerable population.</p>

scholarly journals Annually resolved Atlantic sea surface temperature variability over the past 2,900 y

2020 ◽  
Vol 117 (44) ◽  
pp. 27171-27178
Author(s):  
Francois Lapointe ◽  
Raymond S. Bradley ◽  
Pierre Francus ◽  
Nicholas L. Balascio ◽  
Mark B. Abbott ◽  
...  
Keyword(s):  
North Atlantic ◽  
High Arctic ◽  
Sea Surface ◽  
Anthropogenic Factors ◽  
Multidecadal Variability ◽  
The Past ◽  
The North ◽  
The North Atlantic ◽  
Atmospheric Circulation Anomalies ◽  
Natural Climate

Global warming due to anthropogenic factors can be amplified or dampened by natural climate oscillations, especially those involving sea surface temperatures (SSTs) in the North Atlantic which vary on a multidecadal scale (Atlantic multidecadal variability, AMV). Because the instrumental record of AMV is short, long-term behavior of AMV is unknown, but climatic teleconnections to regions beyond the North Atlantic offer the prospect of reconstructing AMV from high-resolution records elsewhere. Annually resolved titanium from an annually laminated sedimentary record from Ellesmere Island, Canada, shows that the record is strongly influenced by AMV via atmospheric circulation anomalies. Significant correlations between this High-Arctic proxy and other highly resolved Atlantic SST proxies demonstrate that it shares the multidecadal variability seen in the Atlantic. Our record provides a reconstruction of AMV for the past ∼3 millennia at an unprecedented time resolution, indicating North Atlantic SSTs were coldest from ∼1400–1800 CE, while current SSTs are the warmest in the past ∼2,900 y.

scholarly journals A seesaw in Mediterranean precipitation during the Roman Period linked to millennial-scale changes in the North Atlantic

2012 ◽  
Vol 8 (2) ◽  
pp. 637-651 ◽  
Author(s):  
B. J. Dermody ◽  
H. J. de Boer ◽  
M. F. P. Bierkens ◽  
S. L. Weber ◽  
M. J. Wassen ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North Atlantic ◽  
Roman Period ◽  
Sea Surface ◽  
Jet Stream ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean ◽  
Millennial Scale

Abstract. We present a reconstruction of the change in climatic humidity around the Mediterranean between 3000–1000 yr BP. Using a range of proxy archives and model simulations we demonstrate that climate during this period was typified by a millennial-scale seesaw in climatic humidity between Spain and Israel on one side and the Central Mediterranean and Turkey on the other, similar to precipitation anomalies associated with the East Atlantic/West Russia pattern in current climate. We find that changes in the position and intensity of the jet stream indicated by our analysis correlate with millennial changes in North Atlantic sea surface temperature. A model simulation indicates the proxies of climatic humidity used in our analysis were unlikely to be influenced by climatic aridification caused by deforestation during the Roman Period. That finding is supported by an analysis of the distribution of archaeological sites in the Eastern Mediterranean which exhibits no evidence that human habitation distribution changed since ancient times as a result of climatic aridification. Therefore we conclude that changes in climatic humidity over the Mediterranean during the Roman Period were primarily caused by a modification of the jet stream linked to sea surface temperature change in the North Atlantic. Based on our findings, we propose that ocean-atmosphere coupling may have contributed to regulating Atlantic Meridional Overturning Circulation intensity during the period of analysis.

scholarly journals Hydrological relationship between the North Atlantic Ocean and the Mediterranean Sea during the past 15-75 kyr

1999 ◽  
Vol 14 (5) ◽  
pp. 626-638 ◽  
Author(s):  
Martine Paterne ◽  
Nejib Kallel ◽  
Laurent Labeyrie ◽  
Maryline Vautravers ◽  
Jean-Claude Duplessy ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The Past ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean

scholarly journals Space-Time Sea Surface pCO2 Estimation in the North Atlantic Based on CatBoost

2021 ◽  
Vol 13 (14) ◽  
pp. 2805
Author(s):  
Hongwei Sun ◽  
Junyu He ◽  
Yihui Chen ◽  
Boyu Zhao
Keyword(s):  
North Atlantic ◽  
Function Analysis ◽  
Biological Activities ◽  
Mixed Layer Depth ◽  
Sea Surface ◽  
Coefficient Of Determination ◽  
Mean Bias Error ◽  
Bias Error ◽  
The North ◽  
The North Atlantic

Sea surface partial pressure of CO2 (pCO2) is a critical parameter in the quantification of air–sea CO2 flux, which plays an important role in calculating the global carbon budget and ocean acidification. In this study, we used chlorophyll-a concentration (Chla), sea surface temperature (SST), dissolved and particulate detrital matter absorption coefficient (Adg), the diffuse attenuation coefficient of downwelling irradiance at 490 nm (Kd) and mixed layer depth (MLD) as input data for retrieving the sea surface pCO2 in the North Atlantic based on a remote sensing empirical approach with the Categorical Boosting (CatBoost) algorithm. The results showed that the root mean square error (RMSE) is 8.25 μatm, the mean bias error (MAE) is 4.92 μatm and the coefficient of determination (R2) can reach 0.946 in the validation set. Subsequently, the proposed algorithm was applied to the sea surface pCO2 in the North Atlantic Ocean during 2003–2020. It can be found that the North Atlantic sea surface pCO2 has a clear trend with latitude variations and have strong seasonal changes. Furthermore, through variance analysis and EOF (empirical orthogonal function) analysis, the sea surface pCO2 in this area is mainly affected by sea temperature and salinity, while it can also be influenced by biological activities in some sub-regions.

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