Label: Community Records - 061 • Format: Cassette Compilation Turquoise • Country: US • Genre: Rock • Style: Punk, Indie Rock, Hardcore, Experimental
Model description paper 04 Dec Correspondence : Giorgio Spada giorgio. Using a pseudo-spectral approach complemented by a spatial discretization on an icosahedron-based spherical geodesic grid, SELEN 4 solves a generalized sea-level equation SLE for a spherically symmetric Earth with linear viscoelastic rheology, taking the Hot In Herre (DJ-Kicks) - Various - !K7150 of the shorelines and the rotational feedback on sea level into account.
The approach is gravitationally and topographically self-consistent, since it considers the gravitational interactions between the solid Earth, the cryosphere, and the oceans, and it accounts for the evolution of the Earth's W.O.S. - Various - Community Records Compilation Volume 5 in response to changes in sea level.
The SELEN 4 program can be employed to study a broad range of geophysical effects of GIA, including past relative sea-level variations induced by the melting of the Late Pleistocene ice sheets, the time evolution of paleogeography and of the ocean function since the Last Glacial Maximum, the history of the Earth's rotational variations, present-day geodetic signals observed by Global Navigation Satellite Systems, and gravity field variations detected by satellite gravity missions like GRACE the Gravity Recovery and Climate Experiment.
Along with the source code, we provide a supplementary document with a full account of the theory, some numerical results obtained from a standard run, and a user guide. In the last few decades, glacial isostatic adjustment GIA modeling has progressively gained a central W.O.S. - Various - Community Records Compilation Volume 5 in the study of contemporary sea-level change. Sea-level variations observed at the tide gauges deployed along the world's coastlines need to be corrected for the effect of GIA to assess the impact of global warming.
For W.O.S. - Various - Community Records Compilation Volume 5 review of the development of GIA modeling, the reader is referred to WhitehouseSpada W.O.S. - Various - Community Records Compilation Volume 5 , and Whitehouse This new structure facilitates code portability, reusability, and customization, enabling the adaptation of SELEN 4 to new use cases.
Particular attention has been paid to the optimization of the SLE solver, resulting in a large extent of shared-memory parallelism, which allows for an efficient scaling to high resolutions on multi-core systems.
SELEN 4 still takes advantage of GMT version 4 to produce various graphical outputs through plotting scripts included in the distribution package. In the benchmark tests, simplified surface loads have been employed, and the rotational effects have been ignored. In a further benchmark effort, we are planning to adopt a realistic description of the surface load and the contribution from the Earth's rotation.
The paper is organized into three main sections. In Sect. In an attempt to simplify the presentation, and to obtain compact expressions for all the quantities involved, we are not exactly following the traditional notation adopted in the literature since the seminal paper by Farrell and Clarkhereafter referred to The Darkest Of Rooms - David Donohoe - Please Dissolve In This FC W.O.S.
- Various - Community Records Compilation Volume 5 SELEN 4 program is written in a plain way, adopting constants and variables names that follow the same notation employed in this theory section and in SSM19, with the aim of facilitating code readability.
We consider the system composed by the ice and Smash - The Rasmus - Легенды Рока water in the oceans at a given time t. Its mass can be expressed as. According to Eq. We remark that due to the horizontal migration of the shorelines and to the transition W.O.S. - Various - Community Records Compilation Volume 5 floating and grounded ice, O and C are, in general, time dependent.
Accordingly, using Eq. Since mass must be conserved, we have. From Eq. Hereinafter, we shall consider only plausible surface loads, which we define here as those loads for which the mass is conserved. The SLE, however, does not rely upon such assumptions, since it defines a gravitationally self-consistent and non-uniform mass distribution over the oceans. The sea-level equation expresses the relationship between sea-level change, the sea surface variation, and the vertical displacement of the solid Earth.
In this section, various forms of this relationship are described. Above, sea level B has been qualitatively defined as the offset between the sea surface and the surface of the solid Earth. The sea surface variation is tightly associated with variations in the Earth's gravity field.
Indeed, FC76 have shown that. Note that as a consequence of Eq. Hence, using Eq. We now assume that the responses to surface loading and to changes in the centrifugal potential can be combined linearly.
By the constraint of mass conservation given by Eq. The first, referred to as equivalent sea-level change, is. The second. Evaluating the ocean average of both W.O.S. - Various - Community Records Compilation Volume 5 of Eq. As a consequence W.O.S. - Various - Community Records Compilation Volume 5 that, from Eq. We note that according to the analysis of Mitrovica and Milnethe ocean-averaged terms in Eq.
In the classical FC76 framework, a constant OF is assumed and the effects arising from the Earth's rotation are neglected. Hence, it would be more correct to write. Here, we only note that using Eq. This is accomplished by projecting Eq. For the spectral discretization of Eq. S7 and S8. Two nested iterations are adopted, where the external one refines the topography progressively using the solution of the SLE obtained in the internal one.
Of course, with increasing values of parameters Rl maxn extn intmore accurate results are expected, which however might come with a substantial increase in the computational burden. We assume that the user has installed and executed the program following the indications given in the user guide of SELEN 4. Most of the program outputs discussed in this section have been obtained using the same configuration file that comes with the SELEN 4 package.
However, some results shall be based on different settings, in order to appreciate the sensitivity of the outputs on key configuration parameters. We first describe the GIA model adopted in the test run, which consists of three elements, i.
Then, browsing the output folders of SELEN 4we illustrate and discuss two distinct output sets, pertaining to the past and present effects of GIA on sea-level change and on geodetic variations, respectively. In each W.O.S. - Various - Community Records Compilation Volume 5 the grid cells, the time history of ice thickness is assumed to evolve in a piecewise linear manner, with variable increments of 1.
Thus, to fit the SELEN 4 default input format, we have first mapped the original thickness data on a spherical equal-area Tegmark grid described in Sect. The cells' number is thus a bit larger than the number of cells in the original grid. In addition, we have transformed the original time history in a piecewise constant form with a uniform spacing of 0.
Hence, to avoid any ambiguity, in the following, it shall be referred to as I6G-TR The maps are obtained by direct triangulation of the pixelized ice thickness data using the GMT program pscontour. Note that in regions where small-scale topographic features are present, such as ocean Lazy Boys - Various - Punkalicious Volumes One And Two, interpolating a high-resolution relief model on a coarse Tegmark grid may yield inaccurate results.
In this case, a different approach should be adopted for the realization of topography, for instance, based on a binning algorithm. Other choices of the final topography are of course possible. In Fig. It is apparent that for this model asymptotic values are reached, in both cases, for l exceeding values of several hundred. Some spectral properties of the VM5i model are given in Fig.
Note that ages given in the TP93 database included with SELEN 4 are expressed in radiocarbon years and have not been calibrated to calendar years. Results obtained for the three configurations are shown by different colors.
The black curves have been obtained using the GIA model described in Sect. Of course, the execution time of SELEN 4 increases significantly with respect to the test run, requiring 2. Minor differences can be noted in the early stages of deglaciation, which however do not exceed the typical uncertainty on the observed RSL values. These differences are likely to be caused by the significant changes that the topography undergoes in this early phase in the polar regions, which are better captured by increasing the We Miss You - The Westerners And June - Top Country And Western Hits resolution.
The curves clearly indicate that computationally inexpensive runs can provide reliable results in the far field of the previously glaciated areas e. The map Tequila Sunrise - Various - Trip To Paradise the location of the RSL sites.
From a visual inspection of Fig. For others, the trend of the RSL data is captured satisfactorily see sites, andwhile in some others the fit is quite poor sites, and The identification of the possible sources of the evidenced misfits, which should be measured using rigorous statistical methods after a proper calibration of the ages, is not the purpose of this work. Since the SELEN 4 program is open source, the users can modify the code to account for non-glacial loads and change the configuration to determine more suitable combinations of the basic ingredients of GIA modeling, i.
This implies that SELEN 4 can iteratively reconstruct the time evolution of the coastlines and of the OF, in a fashion that is consistent with the gravitational, rotational, and deformational effects induced by deglaciation for a full account of the theory, the reader is referred to SSM Recently, in the context of GIA modeling, Spada and Galassi have faced the problem of the dynamic evolution of aquaterra, i.
The user can easily obtain maps of the full PT merging maps like that shown in Fig. Light blue areas across the polar regions covered by thick ice at the LGM correspond to places where the ice was grounded below sea level in that epoch. In SELEN 4it is also possible to visualize the full time evolution of the OF in order to better appreciate, for example, the spatiotemporal distribution of the ice shelves, which cannot Space Trucking - Земляне - Концерт В ДК Им.
Орджоникидзе. 1974 (Lathe Cut) seen in this paleotopography map. At the global scale, the major land masses that were exposed at the LGM are clearly visible, as evidenced by the low-elevation green areas; these include Beringia, Sundaland, Patagonia, Sahul, Doggerland, and the East Siberian Arctic Shelf.
Using GIA models, the time evolution of these land masses has been investigated in an a number of papers, also in view of the important implications on the dispersal of modern humans. By increasing the spatial resolution, SELEN 4 can also be employed to resolve the past sea-level variations on a regional scale.
As a specific case study, we consider the Mediterranean Sea. Since on the global scale of Fig. The results are shown in the map of Fig. However, when rotational effects are taken into consideration, this can be done in two different ways, i.
The reader is referred to the literature for a detailed presentation of the two theories and to Sect. We also refer to Martinec and Hagedoorn for a general formulation dealing with rotational effects in GIA modeling.
Here, it is useful to mention that in the traditional treatment the long-term The Fire Within - Assault - Survival In The Street of the Earth is evaluated assuming that the lithosphere is characterized by a finite elastic strength, while in the revised theory the equilibrium rotational shape is, more realistically, only based on the viscous properties of the planet.
Furthermore, the long-term extra flattening due to mantle dynamics is properly accounted for. Dashed and solid curves show results for the traditional and for the revised rotational theories, respectively.
Solid curves in Fig. Dashed curves show results obtained with the traditional theory. The two theories predict similar evolutions of the pole of rotation, which according to Fig. We note that at the time of the rapid melting episode known as meltwater pulse Red River Rock - Various - 50 Years Of Golden Greats MWP-1A, between