Harmonic fluctuations in the relative paleointensity data?

Mapping Intimacies ◽

10.5194/egusphere-egu21-13406 ◽

2021 ◽

Author(s):

Marcia Ernesto ◽

Thamyris Britto ◽

George Caminha-Maciel

Keyword(s):

Power Spectra ◽

South Atlantic ◽

Spectral Peak ◽

Climatic Influence ◽

Relative Paleointensity ◽

Similar Phase ◽

North And South

The existing relative paleointensity (RPI) database allowed the construction of reliable stacking curves for at least the last 1 Myr. Observed fluctuations in the RPI curves suggest both lithologic/climatic influence or geodynamo processes. Stacked power spectra for RPI data from ten North and South Atlantic cores revealed a spectral peak at ~5.3kyr for data covering the last 100 kyr. This signal exhibits a similar phase for most of the series. The observed spectral peak has no apparent correspondence in the benthic O18 spectra from the same cores, suggesting the RPI signal is free from the climatic influence. Therefore, it may be a real geodynamo feature.

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Observed seasonal regimes of North-South Atlantic Ocean interbasin exchange

10.31223/osf.io/ykm29 ◽

2019 ◽

Author(s):

Hamed D. Ibrahim

Keyword(s):

North Atlantic ◽

Climate Models ◽

South Atlantic ◽

Meridional Overturning Circulation ◽

Volume Flux ◽

The South ◽

The North ◽

Basin Scale ◽

Interbasin Exchange ◽

North And South

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.

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The Role of Oceanic Heat Advection in the Evolution of Tropical North and South Atlantic SST Anomalies*

Journal of Climate ◽

10.1175/jcli3961.1 ◽

2006 ◽

Vol 19 (23) ◽

pp. 6122-6138 ◽

Cited By ~ 30

Author(s):

Gregory R. Foltz ◽

Michael J. McPhaden

Keyword(s):

Surface Flux ◽

South Atlantic ◽

Shortwave Radiation ◽

Heat Advection ◽

Horizontal Advection ◽

Latent Heat Loss ◽

North And South ◽

Sst Gradient ◽

Sst Anomalies

Abstract The role of horizontal oceanic heat advection in the generation of tropical North and South Atlantic sea surface temperature (SST) anomalies is investigated through an analysis of the oceanic mixed layer heat balance. It is found that SST anomalies poleward of 10° are driven primarily by a combination of wind-induced latent heat loss and shortwave radiation. Away from the eastern boundary, horizontal advection damps surface flux–forced SST anomalies due to a combination of mean meridional Ekman currents acting on anomalous meridional SST gradients, and anomalous meridional currents acting on the mean meridional SST gradient. Horizontal advection is likely to have the most significant effect on the interhemispheric SST gradient mode through its impact in the 10°–20° latitude bands of each hemisphere, where the variability in advection is strongest and its negative correlation with the surface heat flux is highest. In addition to the damping effect of horizontal advection in these latitude bands, evidence for coupled wind–SST feedbacks is found, with anomalous equatorward (poleward) SST gradients contributing to enhanced (reduced) westward surface winds and an equatorward propagation of SST anomalies.

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Microplastics pollution in North and South Atlantic Ocean surface waters

10.5194/egusphere-egu21-15851 ◽

2021 ◽

Author(s):

Svetlana Pakhomova ◽

Evgeny Yakushev

Keyword(s):

Atlantic Ocean ◽

Barents Sea ◽

Environmental Concern ◽

World Ocean ◽

Basic Research ◽

South Atlantic ◽

South Atlantic Ocean ◽

Metal Mesh ◽

North And South ◽

Polymer Type

Contamination of the World Ocean by synthetic non-biodegradable material has become a high profile environmental concern. Standardized sampling methods and methods of plastic identification should be developed so that results can be fed into international monitoring strategies to map plastic distribution worldwide. Here we present results of studies carried out on a transect between Troms&#248; and Svalbard and from Montevideo to Antarctica performed with the same sampling procedure onboard Norwegian and Russian ships in 08.2019 and 01.2020 respectively. Microplastic sampling was carried out using a filtering system. Water passed through the system and SPM was collected on a metal mesh screens. All potential plastic particles and fibers were checked for polymeric identification using a PerkinElmer Spotlight ATR-FTIR. The level of confirmed microplastics ranged from 0 to 1.9 items/m3 (0.7 items/m3 in average) on a transect Troms&#248;-Svalbard and from 0 to 2.5 items/m3 (0.4 items/m3 in average) on Montevideo-Antarctica transect. Both data sets were represented by 40% of fragments and 60% of fibers. Polyester was found as the main polymer type for both transects, 46% of microplastics. Other found polymer types were different in the North and South Atlantic Ocean waters. Nylon (polyamide) was the next most common polymer type in South Atlantic which was not found in Northern part. Difference was also observed in higher number of stations without any microplastics in South Atlantic.This work was partly funded by the Norwegian Ministry of Climate and Environment project RUS-19/0001 &#8220;Establish regional capacity to measure and model the distribution and input of microplastics to the Barents Sea from rivers and currents (ESCIMO)&#8221; and the Russian Foundation for Basic Research, research projects 19-55-80004.

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Power spectra of inspiratory nerve activity with lung inflations in cats

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.4.1709 ◽

1988 ◽

Vol 64 (4) ◽

pp. 1709-1720 ◽

Cited By ~ 13

Author(s):

C. A. Richardson

Keyword(s):

High Frequency ◽

Power Spectra ◽

High Peak ◽

Spectral Peak ◽

Respiratory Pattern ◽

Inflation Pressure ◽

High Frequency Peak ◽

Lung Inflation ◽

Consistent Manner ◽

Inspiratory Activity

To investigate the effect of lung inflations on the high-frequency synchrony (70-122 Hz) observed in the inspiratory activity of respiratory motor nerves of decerebrate cats, I applied a step increase in lung inflation pressure at fixed delays into the inspiratory phase and computed power spectra of phrenic neurograms before and during inflation. In 25 decerebrate paralyzed cats the frequency of the high spectral peak was 92.3 +/- 11.1 Hz before and 105.3 +/- 12.1 Hz during the step in inflation pressure, shifting upward by 13.0 +/- 6.0 Hz. For 8 of the 25 cats, the recurrent laryngeal and phrenic neurograms were recorded simultaneously. The high spectral peak was present during inspiration in the recurrent laryngeal power spectra and coherent with the high peak in the phrenic power spectra. In response to lung inflation, the high peak disappeared from the power spectra of the recurrent laryngeal nerve as the inspiratory activity was inhibited; a shift upward in frequency was not detectable. Comparing inspiratory times (TI, based on the phrenic neurograms) for breaths with no lung inflations to those for breaths with lung inflations, I found that lung inflations early in inspiration caused a decrease in TI, lung inflations at intermediates times had no effect on TI, and lung inflations late in inspiration caused an increase in TI. Despite lung inflation decreasing, not affecting, or increasing inspiratory duration and amplitude of the phrenic neurogram, lung inflation always caused a shift upward in the high-frequency peak of the phrenic power density. The fact that lung inflation, a powerful respiratory stimulus, affected the frequency of the high peak in a consistent manner suggests that the high-frequency synchrony is an important and robust feature of the central respiratory pattern generator.

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Reconstructing deglacial North and South Atlantic deep water sourcing using foraminiferal Nd isotopes

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2012.09.036 ◽

2012 ◽

Vol 357-358 ◽

pp. 289-297 ◽

Cited By ~ 65

Author(s):

A.M. Piotrowski ◽

A. Galy ◽

J.A.L. Nicholl ◽

N. Roberts ◽

D.J. Wilson ◽

...

Keyword(s):

Deep Water ◽

South Atlantic ◽

Nd Isotopes ◽

North And South

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Migration of exotic species of ammonites during highstands of sea level

The Paleontological Society Special Publications ◽

10.1017/s2475262200008844 ◽

1992 ◽

Vol 6 ◽

pp. 324-324

Author(s):

Keith Young

Keyword(s):

North America ◽

South America ◽

Exotic Species ◽

Sea Level ◽

South Atlantic ◽

Horn Of Africa ◽

Mozambique Channel ◽

The North ◽

North And South ◽

Early Late

In northeastern Chihuahua and Trans-Pecos Texas, in the early Late Albian zone of Hysteroceras varicosum occurs the Boeseites romeri (Haas) fauna with B. romeri (Hass), B. perarmata (Hass), B. aff. barbouri (Haas), B. cf. howelli (Haas), B.proteus (Haas), Prohysteroceras cf. P. hanhaense Haas, Elobiceras sp., and Dipoloceras (?) sp. B. perarmata has also been collected at Cerro Mercado, near Monclova, Coahuila. Haas originally described this fauna from Angola. Now, from rocks in the same zone in the Sierra Mojada, Coahuila, Mexico, there is a form related to if not identical with Hysteroceras famelicum Van Hoepen, also originally described from Angola and also from the zone of Hysteroceras varicosum.These fossils are known only from southern North America and Angola; they have not been described from the European Tethys. In 1984 I suggested that during the highstand of sea level of the early Late Albian (Hysteroceras varicosum zone) these ammonites migrated from Angola to Mexico and Trans-Pecos Texas via an epeiric seaway extending across the sag between South America and Africa proposed by Kennedy and Cooper. This would be twelve to fifteen million years prior to an oceanic connection between the North and South Atlantic.I would now ask, can similar epeiric seas and highstands of sea level explain the migration of successive European, Tethyan, Jurassic ammonite faunas down the Mozambique Channel and around the horn of Africa into the Neuquen Basin of Argentina before Africa and Antarctica separated, as proposed by Spath.

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