Sub-Arcsecond Millimeter Imaging of Disks and Envelopes: Probing the Density Structure

2002 ◽  
pp. 303-308
Author(s):  
Leslie W. Looney ◽  
Lee G. Mundy ◽  
W. J. Welch
Keyword(s):  
Density Structure

DENSITY STRUCTURE OF CRATONIC LITHOSPHERE MANTLE: A TALE OF FOUR CRATONS

2019 ◽  
Author(s):  
Irina M. Artemieva ◽  
◽  
Alexey Shulgin ◽  
Bing Xia ◽  
Yulia Cherepanova ◽  
...  
Keyword(s):  
Density Structure

scholarly journals Disruption of the Atlantic Meridional Circulation during Deglacial Climates Inferred from Planktonic Foraminiferal Shell Weights

2021 ◽  
Vol 9 (5) ◽  
pp. 519
Author(s):  
Stergios D. Zarkogiannis
Keyword(s):  
Atlantic Ocean ◽  
Meridional Circulation ◽  
Order Approximation ◽  
Planktonic Foraminifera ◽  
Sediment Cores ◽  
Meridional Overturning Circulation ◽  
Density Structure ◽  
Last Interglacial ◽  
Shell Weight ◽  
The North

Changes in the density structure of the upper oceanic water masses are an important forcing of changes in the Atlantic Meridional Overturning Circulation (AMOC), which is believed to widely affect Earth’s climate. However, very little is known about past changes in the density structure of the Atlantic Ocean, despite being extensively studied. The physical controls on planktonic foraminifera calcification are explored here, to obtain a first-order approximation of the horizontal density gradient in the eastern Atlantic during the last 200,000 years. Published records of Globigerina bulloides shells from the North and Tropical eastern Atlantic were complemented by the analysis of a South Atlantic core. The masses of the same species shells from three different dissolution assessed sediment cores along the eastern Atlantic Ocean were converted to seawater density values using a calibration equation. Foraminifera, as planktonic organisms, are subject to the physical properties of the seawater and thus their shells are sensitive to buoyancy forcing through surface temperature and salinity perturbations. By using planktonic foraminifera shell weight as an upper ocean density proxy, two intervals of convergence of the shell masses are identified during cold intervals of the last two deglaciations that may be interpreted as weak ocean density gradients, indicating nearly or completely eliminated meridional circulation, while interhemispheric Atlantic density differences appear to alleviate with the onset of the last interglacial. The results confirm the significance of variations in the density of Atlantic surface waters for meridional circulation changes.

The density structure of Titan’s outer ice shell

Icarus ◽  
2021 ◽  
Vol 364 ◽  
pp. 114466
Author(s):  
Ondřej Čadek ◽  
Klára Kalousová ◽  
Jakub Kvorka ◽  
Christophe Sotin
Keyword(s):  
Density Structure ◽  
Ice Shell

DENSITY OSCILLATION FROM NANOSCALE TO MACROSCALE

2008 ◽  
Vol 22 (27) ◽  
pp. 2649-2658 ◽  
Author(s):  
X. Y. CHEN ◽  
Y. LIU ◽  
J. M. YANG
Keyword(s):  
Molecular Dynamics ◽  
Channel Flow ◽  
Channel Width ◽  
Density Structure ◽  
Flux Rate ◽  
Confined Fluid ◽  
Threshold Channel ◽  
Micro Channels ◽  
Confined Flow ◽  
Density Oscillation

The effect of channel width on the density structure of confined fluid in the nano-/micro-channels is examined by equilibrium molecular dynamics (EMD) simulation. It was found that the density oscillation occurs near the wall in both cases of the macroscale or nanoscale confined flow. There exists a threshold channel width L threshold , when channel width H<L threshold , density oscillates throughout the channel. When H>L threshold , L threshold is constant and about 5–6 molecular diameter long, and the density becomes uniform beyond this threshold layer. A newly defined ch number may serve to be the parameter to compare similarity in the micro-/nano-scale channel flow. Moreover, the effect of the density oscillation on fluid mass flux rate is examined quantitatively. The result shows that the effect should be considered when the channel width is below 5 molecular diameter.

An extended velocity projection method for estimating the subsurface current and density structure for coastal plume regions: An application to the Chesapeake Bay outflow plume

2005 ◽  
Vol 25 (11) ◽  
pp. 1303-1319 ◽  
Author(s):  
Avijit Gangopadhyay ◽  
Colin Y. Shen ◽  
George O. Marmorino ◽  
Richard P. Mied ◽  
Gloria J. Lindemann
Keyword(s):  
Chesapeake Bay ◽  
Projection Method ◽  
Density Structure ◽  
Subsurface Current ◽  
Velocity Projection

The Density Structure of Highly Compact H [CSC]ii[/CSC] Regions

2000 ◽  
Vol 542 (2) ◽  
pp. L143-L146 ◽  
Author(s):  
José Franco ◽  
Stan Kurtz ◽  
Peter Hofner ◽  
Leonardo Testi ◽  
Guillermo García-Segura ◽  
...  
Keyword(s):  
Density Structure

Combining the deep Earth and lithospheric gravity field to study the density structure of the upper mantle

2021 ◽  
Author(s):  
Bart Root ◽  
Javier Fullea ◽  
Jörg Ebbing ◽  
Zdenek Martinec
Keyword(s):  
Gravity Field ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Field Data ◽  
Wavelength Region ◽  
Density Structure ◽  
Long Wavelength ◽  
Global Gravity ◽  
Deep Earth

&lt;p&gt;Global gravity field data obtained by dedicated satellite missions is used to study the density distribution of the lithosphere. Different multi-data joint inversions are using this dataset together with other geophysical data to determine the physical characteristics of the lithosphere. The gravitational signal from the deep Earth is usually removed by high-pass filtering of the model and data, or by appropriately selecting insensitive gravity components in the inversion. However, this will remove any long-wavelength signal inherent to lithosphere. A clear choice on the best-suited approach to remove the sub-lithospheric gravity signal is missing.&amp;#160;&lt;/p&gt;&lt;p&gt;Another alternative is to forward model the gravitational signal of these deep situated mass anomalies and subtract it from the observed data, before the inversion. Global tomography provides shear-wave velocity distribution of the mantle, which can be transformed into density anomalies. There are difficulties in constructing a density model from this data. Tomography relies on regularisation which smoothens the image of the mantle anomalies. Also, the shear-wave anomalies need to be converted to density anomalies, with uncertain conversion factors related to temperature and composition. Understanding the sensitivity of these effects could help determining the interaction of the deep Earth and the lithosphere.&lt;/p&gt;&lt;p&gt;In our study the density anomalies of the mantle, as well as the effect of CMB undulations, are forward modelled into their gravitational potential field, such that they can be subtracted from gravity observations. The reduction in magnitude of the density anomalies due to the regularisation of the global tomography models is taken into account. The long-wavelength region of the density estimates is less affected by the regularisation and can be used to fix the mean conversion factor to transform shear wave velocity to density. We present different modelling approaches to add the remaining dynamic topography effect in lithosphere models. This results in new solutions of the density structure of the lithosphere that both explain seismic observations and gravimetric measurements. The introduction of these dynamic forces is a step forward in understanding how to properly use global gravity field data in joint inversions of lithosphere models.&lt;/p&gt;

scholarly journals Effect of longitudinal density structure on a straight magnetic field modelling coronal arcade oscillations

2007 ◽  
Vol 471 (3) ◽  
pp. 999-1009 ◽  
Author(s):  
G. R. Donnelly ◽  
A. J. Díaz ◽  
B. Roberts
Keyword(s):  
Magnetic Field ◽  
Density Structure ◽  
Field Modelling
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