scholarly journals Cape Verde Frontal Zone in summer 2017: lateral transports of mass, dissolved oxygen and inorganic nutrients

Ocean Science ◽  
2021 ◽  
Vol 17 (3) ◽  
pp. 769-788
Author(s):  
Nadia Burgoa ◽  
Francisco Machín ◽  
Ángel Rodríguez-Santana ◽  
Ángeles Marrero-Díaz ◽  
Xosé Antón Álvarez-Salgado ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
North Atlantic ◽  
Frontal Zone ◽  
Cape Verde ◽  
Inorganic Nutrients ◽  
Inorganic Nutrient ◽  
The North ◽  
Nutrient Imbalances ◽  
Circulation Patterns ◽  
Horizontal And Vertical Distribution

Abstract. The circulation patterns in the confluence of the North Atlantic subtropical and tropical gyres delimited by the Cape Verde Front (CVF) were examined during a field cruise in summer 2017. We collected hydrographic data, dissolved oxygen (O2) and inorganic nutrients along the perimeter of a closed box embracing the Cape Verde Frontal Zone (CVFZ). The detailed spatial (horizontal and vertical) distribution of water masses, O2 and inorganic nutrients in the CVF was analyzed, allowing for the independent estimation of the transports of these properties in the subtropical and tropical domains down to 2000 m. Overall, at surface and central levels, a net westward transport of 3.76 Sv was observed, whereas at intermediate levels, a net 3 Sv transport northward was obtained. We observed O2 and inorganic nutrient imbalances in the domain consistent with O2 consumption and inorganic nutrient production by organic matter remineralization, resulting in a net transport of inorganic nutrients to the ocean interior by the circulation patterns.

scholarly journals Lateral transports of mass, inorganic nutrients and dissolved oxygen in the Cape Verde Frontal Zone in summer 2017

2020 ◽  
Author(s):  
Nadia Burgoa ◽  
Francisco Machín ◽  
Ángel Rodríguez-Santana ◽  
Ángeles Marrero-Díaz ◽  
Xosé Antón Álvarez-Salgado ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Frontal Zone ◽  
Circulation Pattern ◽  
Cape Verde ◽  
Inorganic Nutrients ◽  
Intermediate Water ◽  
Southeastern Part ◽  
The North ◽  
Circulation Patterns ◽  
Intermediate Waters

Abstract. The circulation patterns in the confluence of the North Atlantic Subtropical and Tropical gyres delimited by the Cape Verde Frontal Zone (CVFZ) in summer 2017 were examined. Hydrology, dissolved oxygen (O2) and inorganic nutrients data collected in a closed box embracing the CVFZ allowed estimating transports of water masses, O2 and inorganic nutrients for the first time. Higher transports occurred mainly at the surface and central waters, and were moderately affected by the Cape Verde Front located in the southeastern part of the domain. Thus, the front conditioned the meridional transports, acting as a barrier between North and South Atlantic Central waters. Specifically, −3.2±1.7 Sv entered through north and east and 6.7±1.7 Sv left through west and south transects. At intermediate levels, the most important source came from the south with −2.2±1.5 Sv of modified Antarctic Intermediate water, moderately affected by the circulation pattern above. The transports of O2 and inorganic nutrients conditioned by their distributions behaved quite similar to mass transports. The most intense and important transports of O2 and inorganic nutrients occurred in the deepest layer of central waters and in the shallowest two layers of intermediate waters where inorganic nutrients accumulated and large differences in concentrations of O2 were found, especially in the deepest layer of central waters between the northeast and southeast zones. In these three layers, transports of O2 and inorganic nutrients came from the east and south and they left northward and westward. This circulation pattern delivers inorganic nutrient from east and south to oligotrophic waters of north and west of CVFZ. Nevertheless, it can also hinders the ventilation of the deepest layer of central waters and the shallowest two layers of intermediate waters.

Deep water circulation patterns in the Atlantic during MISs 12-11

2020 ◽  
Author(s):  
Jasmin M. Link ◽  
Norbert Frank
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Glacial Maximum ◽  
Water Circulation ◽  
Water Masses ◽  
Overturning Circulation ◽  
The Past ◽  
The North ◽  
Circulation Patterns ◽  
The North Atlantic

<p>Glacial Termination V is one of the most extreme glacial-interglacial transitions of the past 800 ka [1]. However, the changes in orbital forcing from Marine Isotope Stage (MIS) 12 to 11 are comparatively weak. In addition, MIS 11c is exceptionally distinct compared to other interglacials with for example a longer duration [2] and a higher-than-present sea level [3] despite a relative low incoming insolation. Therefore, the term “MIS 11 paradox” was coined [4]. However, only little is known about the Atlantic overturning circulation during this time interval [e.g. 5,6].</p><p>Here, we present Atlantic-wide deep water circulation patterns spanning the glacial maximum of MIS 12, Termination V, and MIS 11. Therefore, sediment cores throughout the Atlantic were analyzed regarding their Nd isotopic composition of authigenic coatings to reconstruct the provenance of the prevailing bottom water masses.</p><p>During the glacial maximum of MIS 12, the deep Atlantic Ocean was bathed with a higher amount of southern sourced water compared to the following interglacial. Termination V is represented by a sharp transition in the high-accumulating sites from the North Atlantic with a switch to northern sourced water masses. MIS 11 is characterized through an active deep water formation in the North Atlantic with active overflows from the Nordic Seas, only disrupted by a short deterioration. A strong export of northern sourced water masses to the South Atlantic points to an overall strong overturning circulation.</p><p> </p><p>[1] Lang and Wolff 2011, Climate of the Past 7: 361-380.</p><p>[2] Candy et al. 2014, Earth-Science Reviews 128: 18-51.</p><p>[3] Dutton et al. 2015, Science 349: aaa4019.</p><p>[4] Berger and Wefer 2003, Geophysical Monograph 137: 41-60.</p><p>[5] Dickson et al. 2009, Nature Geoscience 2: 428-433.</p><p>[6] Vázquez Riveiros et al. 2013, EPSL 371-372: 258-268.</p>

scholarly journals Recent Trends in the Recurrence of North Atlantic Atmospheric Circulation Patterns

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Pascal Yiou ◽  
Julien Cattiaux ◽  
Aurélien Ribes ◽  
Robert Vautard ◽  
Mathieu Vrac
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Emerging Trends ◽  
Circulation Patterns ◽  
Long Term Trends ◽  
Recent Trends ◽  
The Stability ◽  
Climate Events

A few types of extreme climate events in the North Atlantic region, such as heatwaves, cold spells, or high cumulated precipitation, are connected to the recurrence of atmospheric circulation patterns. Understanding those extreme events requires assessing long-term trends of the atmospheric circulation. This paper presents a set of diagnostics of the intra- and interannual recurrence of atmospheric patterns. Those diagnostics are devised to detect trends in the stability of the circulation and the return period of atmospheric patterns. We detect significant emerging trends in the winter circulation, pointing towards a potential increased predictability. No such signal seems to emerge in the summer. We find that the winter trends in the dominating atmospheric patterns and their recurrences do not depend of the patterns themselves.

scholarly journals Synoptic influences on springtime tropospheric O<sub>3</sub> and CO over the North American export region observed by TES

2009 ◽  
Vol 9 (11) ◽  
pp. 3755-3776 ◽  
Author(s):  
J. Hegarty ◽  
H. Mao ◽  
R. Talbot
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North American ◽  
East Coast ◽  
North Atlantic Ocean ◽  
Free Troposphere ◽  
The North ◽  
Circulation Patterns ◽  
The Us ◽  
Us East Coast

Abstract. The relationship between synoptic circulation patterns over the western North Atlantic Ocean in spring (March, April, and May) and tropospheric O3 and CO was investigated using retrievals from the Tropospheric Emission Spectrometer (TES) for 2005 and 2006. Seasonal composites of TES retrievals reprocessed to remove the artificial geographic structure added from the a priori revealed a channel of slightly elevated O3 (>55 ppbv) and CO (>115 ppbv) at the 681 hPa retrieval level between 30° N and 45° N extending from North America out over the Atlantic Ocean. Ozone and CO in this region were correlated at r=0.22 with a slope value of 0.13 mol mol−1 indicative of the overall impact of photochemical chemical processes in North American continental export. Composites of TES retrievals for the six predominant circulation patterns identified as map types from sea level pressure fields of the NCEP FNL analyses showed large variability in the distribution of tropospheric O3. Map types MAM2 and MAM3 featuring cyclones near the US east coast produced the greatest export to the lower free troposphere with O3>65 ppbv and a relatively well-defined O3-CO correlation (slope values near 0.20 mol mol−1). The ensembles of HYSPLIT backward trajectories indicated that the high O3 levels were possibly a result of pollutants lofted to the free troposphere by the warm conveyor belt (WCB) of a cyclone. An important finding was that pollutant export occurred in the main WCB branch to the east of the cyclone and in a secondary branch circling to the back of the cyclone center. Conversely, a map type featuring a large anticyclone dominating the flow over the US east coast (MAM6) restricted export with O3 levels generally <55 ppbv and CO levels generally <110 ppbv. There was also evidence of stratospheric intrusions particularly to the north of 45° N in the 316 hPa composites predominately for MAM1 which featured a large cyclone near Newfoundland. However, the concurrence of these intrusions with pollutant export, specifically in the southwestern North Atlantic Ocean, made it difficult to delineate their respective contributions to the 681 hPa O3 composites.

scholarly journals Ventilation time scales of the North Atlantic subtropical cell revealed by coral radiocarbon from the Cape Verde Islands

2015 ◽  
Vol 30 (7) ◽  
pp. 938-948 ◽  
Author(s):  
Alvaro Fernandez ◽  
Thomas J. Lapen ◽  
Rasmus Andreasen ◽  
Peter K. Swart ◽  
Christopher D. White ◽  
...  
Keyword(s):  
Time Scales ◽  
North Atlantic ◽  
Cape Verde ◽  
Cape Verde Islands ◽  
Ventilation Time ◽  
The North ◽  
The North Atlantic ◽  
Subtropical Cell

Linkages between atmospheric circulation, climate and streamflow in the northern North Atlantic: research prospects

2006 ◽  
Vol 30 (2) ◽  
pp. 143-174 ◽  
Author(s):  
D. G. Kingston ◽  
D. M. Lawler ◽  
G. R. McGregor
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Analytical Techniques ◽  
Eastern Canada ◽  
Natural Systems ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Circulation Patterns ◽  
Northwest Europe ◽  
The North Atlantic Oscillation

This paper evaluates the relationships between atmospheric circulation, climate and streamflow in the northern North Atlantic region over the last century and especially the last 50 years. Improved understanding of climatic influences on streamflow is vital given the great importance of fluvial processes to natural systems and water resources, especially in the light of recent and predicted climate change. The main focus lies with climatic and hydrologic implications of the major circulation patterns in the northern North Atlantic, namely the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO). The studies reviewed here reveal key relationships between circulation, climate and streamflow across the northern North Atlantic, allowing the construction of a simple conceptual model for this system. Generally positive NAO/AO-streamflow relationships are found in northwest Europe and northeast USA, with both positive and negative NAO/AO-streamflow linkages apparent for parts of eastern Canada. To help promote a better understanding of the system, several research gaps are identified and critically examined, including: the spatial scope and coverage of investigations; data quality and homogeneity; appropriateness of analytical techniques; and the need for greater knowledge and technique sharing between hydrology and climatology, particularly regarding the rigorous characterization of atmospheric circulation patterns. Among these, the development of seasonally varying, or mobile, NAO indices, to capture variations in subseasonal, seasonal and annual movements in the centres of action, and the need to develop analyses of more hydrologically meaningful climate variables beyond conventional time averaged statistics, are deemed particularly important.

PLANETARY UPPER-LEVEL FRONTAL ZONE IN THE EURO-ATLANTIC SECTOR IN SUMMER DURING 1990-2019

2021 ◽  
pp. 24-33
Author(s):  
E. A. Durneva ◽  
◽  
O. G. Chkhetiani ◽  
◽  
◽  
...  
Keyword(s):  
North Atlantic ◽  
Frontal Zone ◽  
Atmospheric Blocking ◽  
Normal Position ◽  
Summer Period ◽  
Atlantic Sector ◽  
The North ◽  
European Part Of Russia ◽  
Upper Level ◽  
June July

The analysis of monthly mean locations of the planetary upper-level frontal zone in the Euro-Atlantic sector in summer during 1990-2019 is presented. Specific positions for the summer months (June, July, and August) are noted and maximum northward displacements from the climatological normal for 1961-1990 are found in the years with the formation of the atmospheric blocking. The values of standard deviations of the displacements relative to the normal position were calculated for the summer period of each year both for the North Atlantic, Europe, and the European part of Russia and for the Euro-Atlantic sector. On the basis of linear regression, a tendency is revealed toward an increase in the meridional displacements of the planetary upper-level frontal zone over the recent thirty years and toward the occurrence of maximum deviations over the last decade.

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