1,721,022 research outputs found
Replication Data for: Sasgen, I. Arctic glaciers record wavier circumpolar winds, Nature Clim. Change, 2022, https://doi.org/10.1038/s41558-021-01275-4
No full textPublished are the source data underlying Fig. 1, 2 and 4 of Sasgen et al. 2022, Arctic glaciers record wavier circumpolar winds, Nature Clim. Change, doi: 10.1038/s41558-021-01275-4, enabling the reproduction of Fig. 3 and Fig. 5, as well
Replication Data for: Hörhold, M. et al. Modern temperatures in central–north Greenland warmest in past millennium. Nature 613, 503–508 (2023).
No full textMelt reconstruction based on ice core temperatures and model output. The melt reconstruction is based on the linear regression of NGT-2012 temperatures and MAR3.5.2 meltwater runoff anomalies for the period 1871 and 2012 A.D.; meltwater runoff is then reconstructed using NGT-2012 temperatures for 1000 to 1870 A.D. based on the derived regression coefficient. Details are given in section 'Reconstruction of pre-industrial meltwater run-off distribution' in Methods of the paper, https://doi.org/10.1038/s41586-022-05517-z. The data are underlying Fig. 4b (probability distribution)
Increasing Freshwater Fluxes from the Greenland Ice Sheet Observed from Space
No full textPhysical and Space Geodes
Greenland Ice Sheet mass balance GRACE/GRACE-FO (2003-2019) and SMB-D (1948-2019)
No full textData underlying figures 1, 2, 3 and 5.
Figure 1: Monthly mass changes of the Greenland Ice Sheet from GRACE/GRACE-FO and SMB-D (2003-2019)
Figure 2: Biennial mass balance and its components from GRACE/GRACE-FO and SMB-D (2003-2018) for the Greenland Ice Sheet, along with regional estimates for 2017-2018 for East and West.
Figure 3: Rate of mass change for year 2019 from GRACE/GRACE-FO and SMB-D
Figure 5: Annual mass balance and its main components from SMB-D (1948-2019) and GRACE/GRACE-FO (2003-2019
rates of geoid height change and radial displacement due to present and past ice mass variations
Full text linkThis study is concerned with the forward modelling of the present-day glacial-isostatic adjustment (GIA) of the earth to present and past changes of the Antarctic ice sheet (AIS). We predict temporal variations in the geoid height and topographic height within the context of the Gravity Recovery and Climate Experiment (GRACE) satellite mission and terrestrial Global Positioning System (GPS) stations in Antarctica. We first adopt an elastic-compressible earth model and calculate the earth's response to seasonal (< 1 a) and secular (~ 100 a) ice-mass changes. Then, we consider a viscoelastic-incompressible earth model and determine the earth's response to the melting of the AIS since the last glacial maximum (LGM), i.e. the post-glacial rebound (PGR). Both models are radially symmetric and self gravitating. A range of viscosity values account for the uncertainty in the viscosity stratification and the lateral heterogeneity of the mantle beneath Antarctica. We employ six load models simulating the most important temporal aspects of the AIS's evolution. Finally, we predict the geoid-height change and the land uplift and compare them with recent GRACE observations and determinations of the uplift rate for the permanent GPS stations along the Antarctic coast.repor
Glacial isostatic adjustment and sea level change near Berkner Island, Antarctica
Full text linkThe glacial-isostatic adjustment in Iceland resulting from the recent melting of the Vatnajökull ice cap is controlled by the viscosity distribution in the earth's interior and by the details of the melting history. Interpretations of the results of GPS and gravity measuring campaigns in the time interval 1991-2000 and 1992-1999, respectively, by means of laterally homogeneous earth models for the determination of the lithosphere thickness, the asthenosphere thickness and the asthenosphere viscosity have so far been not fully satisfactory. In particular near the ice margin, the fitting of the computed land uplift and gravity change to the observational data was inadequate, which may be related to the neglegt of the Iceland plume in the laterally homogeneous earth models. In the present study, a program package is used for the modelling of the land uplift and gravity change that allows the computation of load-induced perturbations of a Maxwell-viscoelastic, incompressible, self-gravitating, spherical earth model. To simulate the presence of the plume below the Vatnajökull, an axisymmetric viscosity distribution is used, where the plume radius and the plume viscosity are free parameters. Based on seismic results, a 6-km-thick lithosphere is assumed above the plume, which thickens to 35 km in the peripheral region of the plume. The melting history of the Vatnajökull is founded on interpretations of geomorphological and climatological investigations and is simulated by a load co-axial with the plume with parabolic profile and time-dependent radius. The results of the modelling favour a plume radius of ~80 km and a plume viscosity of (0.3-1.0) x 10^{18} Pa s.repor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Die Bestimmung der rezenten Eismassenänderung und der glazialisostatischen Anpassung in den Polarregionen durch Satellitengravimetrie und geophysikalische Modellierung
No full textThis work is concerned with the determination of present-day ice-mass changes
and glacial-isostatic adjustment (GIA) in the polar regions from gravity-field
data of the satellite mission Gravity Recovery and Climate Experiment (GRACE).
Aim is the separation of cryospheric mass changes from the mass redistribution
in the Earth’s mantle due to GIA using geophysical modelling and the
determination of the contribution of glaciated areas to global sea-level
change. This is done by analyzing the time series of monthly GRACE gravity-
field solutions with respect to their long-term temporal changes. Filters are
developed to optimize the trade-off between noise and spatial resolution in
the GRACE gravity fields. Also, a method for the evaluation and combination of
GRACE gravity fields from different processing is developed. Forward models of
the potential disturbance due to present-day ice-mass changes and GIA are
adjusted with respect to the GRACE observations and then used to perform a
joint gravity-field inversion for the causative mass changes on and within the
Earth. For small spatial scales (e.g. individual drainage basins of glaciers),
ambiguities in the solution of this gravimetric inverse problem are reduced by
introducing a priori constraints. The relative weight of this information with
respect to the GRACE data allows determining the regional spatial resolution
of the long-term changes in the GRACE gravity fields. The main region of
interest of this work is Antarctica. In addition, investigations concerned
with present-day ice-mass changes in Alaska and Greenland are presented, along
with results on the gravity-field inversion in terms of the viscosity
distribution in the Earth’s mantle under North America.Diese Arbeit beschäftigt sich mit der Bestimmung rezenter Eismassenänderungen
und der glazialisostatischen Anpassung (GIA) in den Polarregionen aus den
Schwerefelddaten der Satellitenmission Gravity Recovery and Climate Experiment
(GRACE). Ziel ist es, die heutigen Massenänderungen in den Eisgebieten von der
durch GIA verursachten Massenumverteilung im Erdmantel mittels
geophysikalischer Modelle zu separieren und den Beitrag der vereister Gebiete
zur globalen Meeresspiegeländerung zu bestimmen. Dazu werden die Zeitreihen
monatlicher GRACE-Schwerefelder in Hinblick auf langzeitliche Änderungen
analysiert. Zum einen werden Filter entwickelt, welche die als komplementär
anzusehende räumliche Auflösung und Genauigkeit der GRACE-Schwerefelder
optimieren. Desweiteren wird eine Methode entwickelt, die es erlaubt, GRACE-
Daten verschiedener Prozessierungszentren zu kombinieren und deren Qualität zu
bewerten. Modelle des durch rezente Eismassenänderungen und GIA verursachten
Störpotentials werden an die GRACE-Beobachtungen angepasst und dann in einer
gemeinsamen Schwerefeldinversion hinsichtlich der ursächlichen
Massenänderungen auf und in der Erde ausgewertet. Bei der Betrachtung
kleinräumiger Skalen (z.B. einzelner Einzugsgebiete von Gletschern) werden
Mehrdeutigkeiten, die bei der Schwerefeldinversion auftreten, durch a priori
Informationen reduziert. Die relative Gewichtung dieser zusätzlichen
Information bezüglich der GRACE-Daten erlaubt es, die regionale Auflösung
langzeitiger Trends in den GRACE-Schwerefeldern zu bestimmen. Im Wesentlichen
wird in dieser Arbeit das Gebiet der Antarktis untersucht. Darüberhinaus
werden Ergebnisse zur Schwerefeldinversion hinsichtlich Eismassenänderung in
Alaska und Grönland sowie hinsichtlich der Viskositätsverteitung im Erdmantel
Nordamerikas präsentiert
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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