Publications
101 results found
Mitchell AJ, Ulicny D, Hampson GJ, et al., 2010, Modelling tidal current-induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin, Central Europe, Sedimentology, Vol: 57, Pages: 359-388, ISSN: 0037-0746
Fang F, Pain CC, Navon IM, et al., 2009, A POD goal-oriented error measure for mesh optimization, International Journal for Numerical Methods in Fluids, Vol: 63, Pages: 185-206, ISSN: 1097-0363
The approach for designing an error measure to guide an adaptive meshing algorithm proposed in Power et al. (Ocean Modell. 2006; 15:3-38) is extended to use a POD adjoint-based method, thus facilitating efficient primal and adjoint integration in time. The aim is to obtain a new mesh that can adequately resolve all the fields at all time levels, with optimal (w.r.t. the functional) efficiency. The goal-based method solves both the primal and adjoint equations to form the overall error norms, in the form of a metric tensor. The tetrahedral elements are then optimized so that they have unit size in Riemannian space defined with respect to the metric tensor.This is the first attempt to use POD to estimate an anisotropic error measure. The metric tensor field can be used to direct anisotropic mesh adaptivity. The resulting mesh is optimized to efficiently represent the solution fields over a given time period. The calculation of the error measures is carried out in the reduced space. The POD approach facilitates efficient integration backwards in time and yields the sensitivity analysis necessary for the goal-based error estimates. The accuracy of both the primal and adjoint-reduced models is thus optimized (through the use of anisotropic mesh adaptivity). In addition, the functional for optimizing meshes has been designed to be consistent with that for 4D Var data assimilation.
Fang F, Pain CC, Navon IM, et al., 2009, Reduced-order modelling of an adaptive mesh ocean model, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Vol: 59, Pages: 827-851
Halgedahl SL, Jarrard RD, Brett CE, et al., 2009, Geophysical and geological signatures of relative sea level change in the upper Wheeler Formation, Drum Mountains, West-Central Utah: A perspective into exceptional preservation of fossils, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol: 277, Pages: 34-56, ISSN: 0031-0182
Fang F, Pain CC, Navon IM, et al., 2009, A POD reduced order unstructured mesh ocean modelling method for moderate Reynolds number flows Ocean Modelling, Ocean Modelling, Vol: 28, Pages: 127-136
Fang F, Pain CC, Navon IM, et al., 2009, A POD reduced order unstructured mesh ocean modelling method for moderate Reynolds number flows, Ocean Modelling, Vol: 28, Pages: 127-136, ISSN: 1463-5003
Brett CE, Allison PA, DeSantis MK, et al., 2009, Sequence stratigraphy, cyclic facies, and lagerstatten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol: 277, Pages: 9-33, ISSN: 0031-0182
Fang F, Pain CC, Navon IM, et al., 2009, A POD reduced-order 4D-Var adaptive mesh ocean modelling approach, Int. J. Numer. Meth. Fluids, Vol: 60, Pages: 709-732
This paper presents a novel approach for inverting a complex ocean model via a proper orthogonal decomposition. The inversion is achieved through the construction of an adjoint model and used to assimilate data in a similar manner to that used in weather forecasting. This is an incredibly important capability for an ocean model, however it is both complex to construct and also can be computationally expensive. The approach proposed here addresses both of these important issues by constructing an efficient and easy to compute adjoint directly from the reduced order model. The approach is demonstrated by inverting for initial conditions in an ocean gyre simulation. The methodology proposed here led directly to the award of a £1M EPSRC grant (EP/I00405X) to develop reduced order and adjoint models for coastal oceanography. Cited 11 times.
Gorman GJ, Piggott MD, Wells MR, et al., 2008, A systematic approach to unstructured mesh generation for ocean modelling using GMT and Terreno, Computers & Geosciences, Vol: 34, Pages: 1721-1731, ISSN: 0098-3004
A systematic approach to unstructured mesh generation for ocean modelling is presented. The method optimises unstructured meshes to approximate bathymetry to a user specified accuracy which may be defined as a function of longitude, latitude and bathymetry. GMT (Generic Mapping Tools) is used to perform the initial griding of the bathymetric data. Subsequently, the Terreno meshing package combines automated shoreline approximation, mesh gradation and optimisation methods to generate high-quality bathymetric meshes. The operation of Terreno is based upon clearly defined error measures and this facilitates the automation of unstructured mesh generation while minimising user intervention and the subjectivity that this can introduce.
Bosence DWJ, Allison PA, 2008, Biotic – Sediment Interactions; an introduction, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol: 270, Pages: 217-219, ISSN: 0031-0182
Allison PA, Hesselbo SP, Brett CE, 2008, Methane seeps on an Early Jurassic dysoxic seafloor, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol: 270, Pages: 230-238, ISSN: 0031-0182
Paul CRC, Allison PA, Brett CE, 2008, The occurrence and preservation of ammonites in the Blue Lias Formation (Lower Jurassic) of Devon and Dorset, England and their palaeoecological, sedimentological and diagenetic significance, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol: 270, Pages: 258-272, ISSN: 0031-0182
Wells MR, Allison PA, Hampson GJ, et al., 2008, Investigating tides in the Early Pennsylvanian Seaway of NW Eurasia using the Imperial College Ocean Model, Geological Association of Canada Special Paper, Vol: 48, Pages: 363-387, ISSN: 0072-1042
Piggott MD, Gorman GJ, Pain CC, et al., 2008, A new computational framework for multi-scale ocean modelling based on adapting unstructured meshes, 9th ICFD Conference on Numerical Methods for Fluid Dynamics, Pages: 1003-1015
A new modelling framework is presented for application to a range of three-dimensional (3D) multi-scale oceanographic problems. The approach is based upon a finite element discretization on an unstructured tetrahedral mesh which is optimized to represent highly complex geometries. Throughout a simulation the mesh is dynamically adapted in 3D to optimize the representation of evolving solution structures. The adaptive algorithm makes use of anisotropic measures of solution complexity and a load-balanced parallel mesh optimization algorithm to vary resolution and allow long, thin elements to align with features such as boundary layers. The modelling framework presented is quite different from the majority of ocean models in use today, which are typically based on static-structured grids. Finite element (and volume) methods on unstructured meshes are, however, gaining popularity in the oceanographic community. The model presented here is novel in its use of unstructured meshes and anisotropic adaptivity in 3D, its ability to represent a range of coupled multi-scale solution structures and to simulate non-hydrostatic dynamics. Copyright (C) 2007 John Wiley & Sons, Ltd.
Bosence DWJ, Allison PA, 2008, Biotic sediment interactions: Selected papers from: Organism sediment relations and preservational windows; A tribute to the scientific career of Roland Goldring. Published in Palaeogeography, Palaeoclimatology, Palaeoecology, Publisher: Elsevier Science Ltd.
Allison PA, Maeda H, TuZino T, et al., 2008, Exceptional preservation within Pleistocene lacustrine sediments of Shiobara, Japan, Palaois, Vol: 23, Pages: 260-266
Wells MR, Allison PA, Hampson GJ, et al., 2008, Investigating tides in the Early Pennsylvanian Seaway of NW Eurasia using the Imperial College Ocean Model, Dynamics of Epeiric Seas, Editors: Pratt BR, Holmden C, Publisher: Geological Association of Canada, Pages: 363-387, ISBN: 9781897095348
Piggott MD, Pain CC, Gorman GJ, et al., 2007, Multi-scale ocean modelling with adapting unstructured grids, CLIVAR Exchanges, Vol: 12, Pages: 21-23, ISSN: 1026-0471
Piggott MD, Pain CC, Gorman GJ, et al., 2007, Multi-scale ocean modelling with adapting unstructured grids, CLIVAR Exchanges, Vol: 12, Pages: 21-23, ISSN: 1026-0471
Wells MR, Allison PA, Piggott MD, et al., 2007, Numerical modeling of tides in the late Pennsylvanian Midcontinent seaway of North America with implications for hydrography and sedimentation, JOURNAL OF SEDIMENTARY RESEARCH, Vol: 77, Pages: 843-865, ISSN: 1527-1404
A novel numerical model (the Imperial College Ocean Model, ICOM) is used to simulate tidal circulation in shallow epicontinental seas connected to large, open oceans. ICOM is validated using the present-day North Sea and applied to predict tidal range in the late Pennsylvanian Midcontinent Seaway (LPMS) of North America. The model simulates the effect of the principal tidal constituents (astronomical tides) as well as the tide propagating from the adjacent open ocean (co- oscillating tide). Two ‘‘base-case’’ Pennsylvanian paleogeographies were tested: (1) a maximum sea-level highstand and (2) the early stages of a transgression. Sensitivity tests determined the importance of paleo-water depth and coastline uncertainty on the prediction of tidal range. During the highstand, tidal ranges in the craton interior (Midcontinent Shelf, Illinois and Appalachian basins) are consistently predicted as microtidal (, 2 m tidal range). Such low tidal ranges would have inhibited water-body mixing in the LPMS, promoting stratification. This, combined with the influx of oxygen-poor water from the Permian Basin to the west and high organic input from tropical rivers, may have contributed to the deposition of ‘‘core’’ black shales in LPMS cyclothems. Conversely, a mesotidal to macrotidal diurnal (once-daily tide) regime is predicted for the early transgression in a large-scale embayment in eastern Kansas due to resonant amplification of diurnal tidal constituents. Pennsylvanian strata here have been ascribed to a mesotidal to macrotidal setting and include cyclic rhythmites that suggest a strongly diurnal system, as predicted by ICOM.
Allison PA, Wells MR, 2006, Circulation in large ancient epicontinental seas: What was different and why?, PALAIOS, Vol: 21, Pages: 513-515, ISSN: 0883-1351
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- Citations: 36
Brett CE, Allison PA, Tsujita CJ, et al., 2006, Sedimentology, taphonomy, and paleoecology of meter-scale cycles from the Upper Ordovician of Ontario, PALAIOS, Vol: 21, Pages: 530-547, ISSN: 0883-1351
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- Citations: 24
Higgs R, Wells MR, Allison PA, et al., 2006, Discussion on large sea, small tides: the Late Carboniferous seaway of NW Europe, JOURNAL OF THE GEOLOGICAL SOCIETY, Vol: 163, Pages: 893-895, ISSN: 0016-7649
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- Citations: 1
Allison PA, Wright VP, 2005, Switching off the carbonate factory: A-tidality, stratification and brackish wedges in epeiric seas, SEDIMENTARY GEOLOGY, Vol: 179, Pages: 175-184, ISSN: 0037-0738
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- Citations: 31
Wells MR, Allison PA, Piggott MD, et al., 2005, Large sea, small tides: the Late Carboniferous seaway of NW Europe, JOURNAL OF THE GEOLOGICAL SOCIETY, Vol: 162, Pages: 417-420, ISSN: 0016-7649
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- Citations: 28
Aguilera-Franco N, Allison P A, 2005, Events of the Cenomanian-Turonian Succession, Southern Mexico, Journal of Iberian Geology, Vol: 31, Pages: 25-50, ISSN: 0378-102X
Wells MR, Allison PA, Hampson GJ, et al., 2005, Modelling ancient tides: the Upper Carboniferous epi-continental seaway of Northwest Europe, Sedimentology, Vol: 52, Pages: 715-735, ISSN: 0037-0746
Allison PA, 2001, Decay, Palaeobiology II, Editors: Briggs, Crowther, Oxford, Publisher: Blackwell Science, Pages: 270-273, ISBN: 9780632051472
Aguilera-Franco N, Hernandez-Romano U, Allison PA, 2001, Biostratigraphy and environmental changes across the Cenomanian–Turonian boundary, southern Mexico, Publisher: Elsevier Science Ltd., Pages: 237-255, ISSN: 0895-9811
Brett CE, Whiteley TE, Allison PA, et al., 1999, The Walcott-Rust Quarry: Middle Ordovician trilobite Konservat-Lagerstatten, 2nd International Trilobite Conference, Publisher: PALEONTOLOGICAL SOC INC, Pages: 288-305, ISSN: 0022-3360
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- Citations: 24
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