| Records |
| Author |
Crouzet N. |
| Title |
Monitoring warm transiting exoplanets for Ariel with ASTEP+ |
Type |
Communication |
| Year |
2021 |
Publication  |
Journée Ariel France, 28 janvier 2021 |
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1066 |
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yes |
| Call Number |
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Serial |
7826 |
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| Author |
Guillot T. |
| Title |
Science of temperate exoplanets: The lessons from Juno |
Type |
Book Chapter |
| Year |
2021 |
Publication |
Journée Ariel France, 28 janvier 2021 |
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1066 |
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Bachelor's thesis |
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yes |
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Serial |
7827 |
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| Author |
Manuele Bazzichetto, François Massol, Marta Carboni, Jonathan Lenoir, Jonas J. Lembrechts, Rémi Joly, David Renault |
| Title |
Once upon a time in the far south: Influence of local drivers and functional traits on plant invasion in the harsh sub-Antarctic islands |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Vegetation Science |
Abbreviated Journal |
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| Volume |
32 |
Issue |
4 |
Pages |
e13057 |
| Keywords |
alien plants anthropogenic propagule pressure cold environments human disturbances plant invasiveness species distribution models topoclimate |
| Abstract |
Aim Here, we aim to: (a) investigate the local effect of environmental and anthropogenic factors on alien plant invasion in sub-Antarctic islands; and (b) explore whether and how functional traits affect alien species dependence on anthropogenic factors in these environments. Location Possession Island, Crozet archipelago (French sub-Antarctic islands). Methods Single-species distribution models were used to explore the effect of high-resolution topoclimatic and human-related variables on the occurrence of six alien plants colonizing French sub-Antarctic islands. Furthermore, plant responses to human-related variables and the effect of those variables in interaction with plant traits were analysed by means of a multi-species distribution model. This allowed identifying functional features mediating the influence of human activities on the occurrence probability of alien plant species. Results We observed two main invasion patterns: (a) species predicted to occur close to the introduction sites, whose occurrence probability appeared to be strongly affected by anthropogenic factors; and (b) species predicted to occur nearly everywhere on Possession Island, except in areas featuring particularly harsh climatic conditions. Differences in the influence of human-related variables on the occurrence of the alien species were mostly related to their life history, plant height and residence time, with perennial and low-statured species introduced earlier appearing less dependent on human-induced dispersal and disturbance. Conclusions We conclude that both topoclimatic and anthropogenic factors affect plant invasion on sub-Antarctic islands. Specifically, species predicted to occur close to their introduction sites appear much more dependent on human presence and activity, potentially due to the lack of key functional traits allowing them to spread successfully across Possession Island under the harsh sub-Antarctic climate. Yet, particularly severe abiotic conditions are a major constraint which equally limits the occurrence of all alien plants, irrespective of their dependence on anthropogenic factors. |
| Programme |
136 |
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1654-1103 |
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Approved |
yes |
| Call Number |
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Serial |
8298 |
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| Author |
Mike Lockwood, Carl Haines, Luke A. Barnard, Mathew J. Owens, Chris J. Scott, Aude Chambodut, Kathryn A. McWilliams |
| Title |
Semi-annual, annual and Universal Time variations in the magnetosphere and in geomagnetic activity: 4. Polar Cap motions and origins of the Universal Time effect |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Space Weather and Space Climate |
Abbreviated Journal |
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| Volume |
11 |
Issue |
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Pages |
15 |
| Keywords |
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| Abstract |
We use the am, an, as and the aσ geomagnetic indices to the explore a previously overlooked factor in magnetospheric electrodynamics, namely the inductive effect of diurnal motions of the Earth’s magnetic poles toward and away from the Sun caused by Earth’s rotation. Because the offset of the (eccentric dipole) geomagnetic pole from the rotational axis is roughly twice as large in the southern hemisphere compared to the northern, the effects there are predicted to be roughly twice the amplitude of those in the northern hemisphere. Hemispheric differences have previously been discussed in terms of polar ionospheric conductivities generated by solar photoionization, effects which we allow for by looking at the dipole tilt effect on the time-of-year variations of the indices. The electric field induced in a geocentric frame is shown to also be a significant factor and gives a modulation of the voltage applied by the solar wind flow in the southern hemisphere that is typically a ±30% diurnal modulation for disturbed intervals rising to ±76% in quiet times. For the northern hemisphere these are 15% and 38% modulations. Motion away from/towards the Sun reduces/enhances the directly-driven ionospheric voltages and reduces/enhances the magnetic energy stored in the tail and we estimate that approximately 10% of the effect appears in directly driven ionospheric voltages and 90% in changes of the rate of energy storage or release in the near-Earth tail. The hemispheric asymmetry in the geomagnetic pole offsets from the rotational axis is shown to be the dominant factor in driving Universal Time (UT) variations and hemispheric differences in geomagnetic activity. Combined with the effect of solar wind dynamic pressure and dipole tilt on the pressure balance in the near-Earth tail, the effect provides an excellent explanation of how the observed Russell-McPherron pattern with time-of-year F and UT in the driving power input into the magnetosphere is converted into the equinoctial F-UT pattern in average geomagnetic activity (after correction is made for dipole tilt effects on ionospheric conductivity), added to a pronounced UT variation with minimum at 02–10 UT. In addition, we show that the predicted and observed UT variations in average geomagnetic activity has implications for the occurrence of the largest events that also show the nett UT variation. |
| Programme |
139 |
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| ISSN |
2115-7251 |
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Approved |
yes |
| Call Number |
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Serial |
8076 |
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| Author |
David Byrne, Jeff Polton, Colin Bell |
| Title |
Creation of a global tide analysis dataset: Application of NEMO and an offline objective analysis scheme |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Operational Oceanography |
Abbreviated Journal |
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Issue |
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Pages |
1-14 |
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| Abstract |
The accurate prediction of tides is vital for the operation of many industries, early warning of coastal flooding and scientific understanding of ocean processes. In this paper, we describe the creation method of a global dataset of tidal harmonics using NEMO (Nucleus for European Modelling of the Ocean) for the first time and an offline objective analysis scheme. Data are assimilated as part of a post-processing step, reducing the computational resources required. A reduced ensemble of tidal harmonics is generated, where each member is run for a shorter period of time than a central background state. This ensemble is used to estimate a single background covariance state, which is used for analysis. Output is validated using an ensemble of objective analyses. For each ensemble member, random selections of observations are omitted and validation is performed at these locations. Improvements in both Mean Absolute Error (MAE) and correlation coefficients (R2) are seen across all 6 of the largest diurnal and semi-diurnal constituents. MAEs in amplitude and phase are reduced by up to 78% and 89%, respectively, and correlations by as much as 0.14. In addition, the majority of locations (between 70 and 80%) see significant improvement. |
| Programme |
688 |
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| ISSN |
1755-876X |
ISBN |
1755-876X |
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yes |
| Call Number |
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Serial |
8338 |
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| Author |
Martin Tournier, Pauline Goulet, Nadège Fonvieille, David Nerini, Mark Johnson, Christophe Guinet |
| Title |
A novel animal-borne miniature echosounder to observe the distribution and migration patterns of intermediate trophic levels in the Southern Ocean |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Marine Systems |
Abbreviated Journal |
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| Volume |
223 |
Issue |
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Pages |
103608 |
| Keywords |
Biologging Diel vertical migration Functional data analysis Marine acoustics Micronekton Sonar tag |
| Abstract |
Despite expanding in-situ observations of marine ecosystems by new-generation sensors, information about intermediate trophic levels remains sparse. Indeed, mid-trophic levels, while encompassing a broad range of zooplankton and micronekton organisms that represent a key component of marine ecosystems and sustain large and diverse communities of marine predators, are challenging to sample and identify. In this study, we examined whether an animal-borne miniature active echosounder can provide information on the distribution and movements of mid-trophic level organisms. If so, such a sonar tag, harnessing the persistent diving behaviour of far-ranging marine mammals, could greatly increase the density of data on this under-studied biome. High-frequency (1.5 MHz) sonar tags were deployed simultaneously with oceanographic tags on two southern elephant seals (Mirounga leonina), at the Kerguelen Islands and Valdés Peninsula (Argentina), and recorded acoustic backscatter while the seals foraged respectively in the Indian and the Atlantic sectors of the Southern Ocean. The backscatter varied widely over time and space, and the seals attempted to capture only a small fraction of the insonified targets. Diel vertical migration patterns were clearly identifiable in the data, reinforcing our confidence in the ability of the sonar tags to detect living mid-trophic organisms along with possibly sinking biological detritus. Moreover, CTD tags attached to the same animals indicated how the abundance, size distribution, and diel migration behaviour of acoustic targets varied with water bodies. These preliminary results demonstrate the potential for animal-borne sonars to provide detailed in-situ information. Further validation effort will make it a valuable tool to refine the estimation of carbon export fluxes as well as for assessing the variation of mid-trophic level biomass according to oceanographic domains and seasons. |
| Programme |
1201 |
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| ISSN |
0924-7963 |
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Approved |
yes |
| Call Number |
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Serial |
8260 |
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| Author |
N. Aubone, M. Saraceno, M. L. Torres Alberto, J. Campagna, L. Le Ster, B. Picard, M. Hindell, C. Campagna, C. R. Guinet |
| Title |
Physical changes recorded by a deep diving seal on the Patagonian slope drive large ecological changes |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Marine Systems |
Abbreviated Journal |
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| Volume |
223 |
Issue |
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Pages |
103612 |
| Keywords |
Elephant seals Malvinas current Patagonian shelf slope Southwestern Atlantic Ocean |
| Abstract |
The Patagonian slope is the region where Subantarctic waters and bathymetry give raise to physical and ecological processes that support a rich biodiversity and a large-scale industrial fisheries. Unique among the species that depend on this region is the deep diving southern elephant seal, Mirounga leonina. We report here on changes in the foraging behavior of a female seal explained by the combined effect of a cold and high salinity water mass and a decrease in surface chlorophyll-a concentration. Behavioral and oceanographic data from about 5000 profiles of temperature, conductivity, pressure, light and prey encounters were collected within an area ranging 59.5–61°W and 46–47.5°S, at depths of 300–700 m, on the Patagonian slope, during November–December 2018. A decrease in temperature (0.15 °C) and an increase in salinity (0.03) was found below the mixed layer, during December. Light data revealed a significant increase of irradiance in December (almost reaching the ocean bottom) associated with a decrease of chlorophyll-a in the upper levels. Concomitantly, the seal had a different diving behavior in December, foraging near the surface at night and close to the bottom during daylight hours. Also, the seal doubled the prey capture attempts in December compared to November. This study reveals the importance of ocean physical properties on seal's diving and foraging behavior, and how this changes, although small, can impact on seals diet and body composition during their post-breeding trips. |
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1201 |
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| ISSN |
0924-7963 |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
8771 |
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| Author |
Afsaneh Mohammadzaheri, Karin Sigloch, Kasra Hosseini, Mitchell G. Mihalynuk |
| Title |
Subducted Lithosphere Under South America From Multifrequency P Wave Tomography |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Geophysical Research: Solid Earth |
Abbreviated Journal |
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| Volume |
126 |
Issue |
6 |
Pages |
e2020JB020704 |
| Keywords |
Andes intra-arc intra-oceanic subduction seismic tomography South America structure of the mantel |
| Abstract |
We analyze mantle structure under South America in the DETOX-P1 seismic tomography model, a global-scale, multifrequency inversion of teleseismic P waves. DETOX-P1 inverts the most extensive data set of broadband, waveform-based traveltime measurements to date, complemented by analyst-picked traveltimes from the ISC-EHB catalog. The mantle under South America is sampled by ∼665,000 cross-correlation traveltimes measured on 529 South American broadband stations and on 5,389 stations elsewhere. By their locations, depths, and geometries, we distinguish four high-velocity provinces under South America, interpreted as subducted lithosphere (“slabs”). The deepest (∼1,800–1,200 km depth) and shallowest (<600 km) slab provinces are observed beneath the Andean Cordillera near the continent’s northwest coast. At intermediate depths (1,200–900 km, 900–600 km), two slab provinces are observed farther east, under Brazil, Bolivia and Venezuela, with links to the Caribbean. We interpret the slabs relative to South America’s paleo-position over time, exploring the hypothesis that slabs sank essentially vertically after widening by viscous deformation in the mantle transition zone. The shallowest slab province carries the geometric imprint of the continental margin and represents ocean-beneath-continent subduction during Cenozoic times. The deepest, farthest west slab complex formed under intra-oceanic trenches during late Jurassic and Cretaceous times, far west of South America’s paleo-position adjoined to Africa. The two intermediate slab complexes record the Cretaceous transition from westward intra-oceanic subduction to eastward subduction beneath South America. This geophysical inference matches geologic records of the transition from Jura-Cretaceous, extensional “intra-arc” basins to basin inversion and onset of the modern Andean arc ∼85 Ma. |
| Programme |
133 |
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Edition |
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| ISSN |
2169-9356 |
ISBN |
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Approved |
yes |
| Call Number |
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Serial |
7991 |
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| Author |
Jun Xie, Risheng Chu, Sidao Ni |
| Title |
Evaluating Global Tomography Models With Antipodal Ambient Noise Cross-Correlation Functions |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Geophysical Research: Solid Earth |
Abbreviated Journal |
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| Volume |
126 |
Issue |
3 |
Pages |
e2020JB020444 |
| Keywords |
ambient noise cross-correlation functions antipodal surface waves mantle heterogeneity tomography model evaluation |
| Abstract |
It is essential to evaluate global tomography models, which provide important information for understanding Earth's structure and dynamics. Long-period surface waves propagating between antipodal stations are good candidates for this purpose since they depend on global-scale velocity variations in the upper mantle. In this study, we extract minor-arc and major-arc Rayleigh waves from ambient noise cross correlations between GEOSCOPE station AIS and ∼1,800 USArray stations near the antipode of AIS. We identify two Rayleigh-wave-focusing regions and simulate the observed maximum amplitude pattern at the antipodal region using synthetic surface waves based on three global tomography models. Our simulations suggest that seismic heterogeneity of the tomography models need to be inflated by a factor of 2–3 in oceanic regions to explain the observed focusing pattern of surface waves near the antipodal region. |
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133 |
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2169-9356 |
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Approved |
yes |
| Call Number |
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Serial |
7993 |
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| Author |
N. Ribeiro, L. Herraiz-Borreguero, S. R. Rintoul, C. R. McMahon, M. Hindell, R. Harcourt, G. Williams |
| Title |
Warm Modified Circumpolar Deep Water Intrusions Drive Ice Shelf Melt and Inhibit Dense Shelf Water Formation in Vincennes Bay, East Antarctica |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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| Volume |
126 |
Issue |
8 |
Pages |
e2020JC016998 |
| Keywords |
AABW Antarctic Coastal Circulation Antarctic Margins basal melt mCDW intrusions seal CTD |
| Abstract |
Antarctic Bottom Water (AABW) production supplies the deep limb of the global overturning circulation and ventilates the deep ocean. While the Weddell and Ross Seas are recognized as key sites for AABW production, additional sources have been discovered in coastal polynya regions around East Antarctica, most recently at Vincennes Bay. Vincennes Bay, despite encompassing two distinct polynya regions, is considered the weakest source, producing Dense Shelf Water (DSW) only just dense enough to contribute to the lighter density classes of AABW found offshore. Here we provide the first detailed oceanographic observations of the continental shelf in Vincennes Bay (104-111°E), using CTD data from instrumented elephant seals spanning from February to November of 2012. We find that Vincennes Bay has East Antarctica’s warmest recorded intrusions of modified Circumpolar Deep Water (mCDW) and that warm mCDW drives basal melt under Vanderford and Underwood ice shelves. Our study also provides the first direct observational evidence for the inflow of meltwater to this region, which increases stratification and hinders DSW formation, and thus AABW production. The Vincennes Bay glaciers, together with the Totten Glacier, drain part of the Aurora Basin, which holds up to 7 m of sea level rise equivalent. Our results highlight the vulnerability of the East Antarctic Ice Sheet to intrusions of mCDW. |
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109 |
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2169-9291 |
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Approved |
yes |
| Call Number |
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Serial |
8211 |
| Permanent link to this record |
