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R D Hyndman - One of the best experts on this subject based on the ideXlab platform.
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the Thermal Structure of subduction zone back arcs
Journal of Geophysical Research, 2006Co-Authors: Claire A Currie, R D HyndmanAbstract:[1] It is well recognized that active arc volcanism at nearly all subduction zones requires temperatures greater than 1200°C in the subarc mantle, despite the underthrusting cool subducting plate. In this study, we document evidence that high upper mantle temperatures are not restricted to the arc but usually extend for several hundred kilometers across the back arc, even in areas that have not undergone extension. For 10 circum-Pacific back arcs where there has been no significant recent extension, we have compiled observational constraints on the Thermal Structure using a number of independent indicators of mantle temperature, including surface heat flow, seismic velocity, and xenolith thermobarometry. The observations indicate uniformly high temperatures in the shallow mantle and a thin lithosphere (1200°C at ∼60 km depth) over back-arc widths of 250 to >900 km. Similar high temperatures are inferred for extensional back arcs of the western Pacific and southern Europe, but the Thermal Structures are complicated by extension and spreading. A broad hot back arc may be a fundamental characteristic of a subduction zone that places important constraints on back-arc mantle dynamics. In particular, the Thermal Structure predicted for slab-driven corner flow is inconsistent with the observed uniformly high back-arc temperatures. We favor the alternate model that heat is rapidly carried upward from depth by vigorous Thermal convection in the back-arc upper mantle. Such convection may be promoted by low viscosities, resulting from hydration by fluids from the subducting plate. Following subduction termination, we find that the high temperatures decay over a timescale of about 300 Myr.
J. Huw Davies - One of the best experts on this subject based on the ideXlab platform.
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Simple analytic model for subduction zone Thermal Structure
Geophysical Journal International, 1999Co-Authors: J. Huw DaviesAbstract:A new analytic model is presented for the Thermal Structure of subduction zones. It applies to the deeper regions of a subduction zone, where the overriding mantle is no longer rigid but flows parallel to the slab surface. The model captures the development of one Thermal boundary layer out into the mantle wedge, and another into the subducting slab. By combining this model with the analytic model of Royden (1993a,b), which applies to regions in which the overriding plate is rigid, a nearly complete analytic model for the Thermal Structure of a steady-state subduction zone can be achieved. A good agreement is demonstrated between the output of the combined analytic model and a numerical finite element calculation. The advantages of this analytic approach include (1) efficiency (only limited computing resources are needed); (2) flexibility (non-linear slab shape, and processes such as erosion, and shear heating are easily incorporated); and (3) transparency (the effect of changes in input variables can be seen directly).
Claire A Currie - One of the best experts on this subject based on the ideXlab platform.
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the Thermal Structure of subduction zone back arcs
Journal of Geophysical Research, 2006Co-Authors: Claire A Currie, R D HyndmanAbstract:[1] It is well recognized that active arc volcanism at nearly all subduction zones requires temperatures greater than 1200°C in the subarc mantle, despite the underthrusting cool subducting plate. In this study, we document evidence that high upper mantle temperatures are not restricted to the arc but usually extend for several hundred kilometers across the back arc, even in areas that have not undergone extension. For 10 circum-Pacific back arcs where there has been no significant recent extension, we have compiled observational constraints on the Thermal Structure using a number of independent indicators of mantle temperature, including surface heat flow, seismic velocity, and xenolith thermobarometry. The observations indicate uniformly high temperatures in the shallow mantle and a thin lithosphere (1200°C at ∼60 km depth) over back-arc widths of 250 to >900 km. Similar high temperatures are inferred for extensional back arcs of the western Pacific and southern Europe, but the Thermal Structures are complicated by extension and spreading. A broad hot back arc may be a fundamental characteristic of a subduction zone that places important constraints on back-arc mantle dynamics. In particular, the Thermal Structure predicted for slab-driven corner flow is inconsistent with the observed uniformly high back-arc temperatures. We favor the alternate model that heat is rapidly carried upward from depth by vigorous Thermal convection in the back-arc upper mantle. Such convection may be promoted by low viscosities, resulting from hydration by fluids from the subducting plate. Following subduction termination, we find that the high temperatures decay over a timescale of about 300 Myr.
François Lott - One of the best experts on this subject based on the ideXlab platform.
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Thermal Structure of the upper atmosphere of Venus simulated by a ground-to-thermosphere GCM
Icarus, 2017Co-Authors: Gabriella Gilli, Sébastien Lebonnois, Francisco González-galindo, Miguel A. López-valverde, Aurélien Stolzenbach, Franck Lefèvre, Jean-yves Chaufray, François LottAbstract:We present here the Thermal Structure of the upper atmosphere of Venus predicted by a full self-consistent Venus General Circulation Model (VGCM) developed at Laboratoire de MMétéorologie Dynamique (LMD) and extended up to the thermosphere of the planet. Physical and photochemical processes relevant at those altitudes, plus a non-orographic GW parameterisation, have been added. All those improvements make the LMD-VGCM the only existing ground-to-thermosphere 3D model for Venus: a unique tool to investigate the atmosphere of Venus and to support the exploration of the planet by remote sounding. The aim of this paper is to present the model reference results, to describe the role of radiative, photochemical and dynamical effects in the observed Thermal Structure in the upper mesosphere/lower thermosphere of the planet. The predicted Thermal Structure shows a succession of warm and cold layers, as recently observed. A cooling trend with increasing latitudes is found during daytime at all altitudes, while at nighttime the trend is inverse above about 110 km, with an atmosphere up to 15 K warmer towards the pole. The latitudinal variation is even smaller at the terminator, in agreement with observations. Below about 110 km, a nighttime warm layer whose intensity decreases with increasing latitudes is predicted by our GCM. A comparison of model results with a selection of recent measurements shows an overall good agreement in terms of trends and order of magnitude. Significant data-model discrepancies may be also discerned. Among them, thermospheric temperatures are about 40-50 K colder and up to 30 K warmer than measured at terminator and at nighttime, respectively. The altitude layer of the predicted mesospheric local maximum (between 100 and 120 km) is also higher than observed. Possible interpretations are discussed and several sensitivity tests performed to understand the data-model discrepancies and to propose future model improvements.
Kathy Cinque - One of the best experts on this subject based on the ideXlab platform.
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numerical study of the Thermal Structure of a stratified temperate monomictic drinking water reservoir
Journal of Hydrology: Regional Studies, 2020Co-Authors: Fuxin Zhang, Hong Zhang, Edoardo Bertone, Rodney Anthony Stewart, Charles James Lemckert, Kathy CinqueAbstract:Abstract Study region Tarago Reservoir, Victoria, Australia. Study focus This study investigates the influence of rainfall, river inflow and wind on the temperature stratification of the Tarago Reservoir by incorporating atmospheric and bathymetric conditions using a three-dimensional hydrodynamic model. New hydrological insights for this region In this study, a three-dimensional (3D) hydrodynamic model was developed and applied to the Tarago Reservoir. The model allowed 3D visualization of the Thermal Structure, and the seasonal and longitudinal differences in stratification could be quantified using the Schmidt stability index. The simulation results revealed longitudinal differences in Thermal Structure among the riverine, transition, and lacustrine zones. The bathymetry affects the lake stratification and stability; furthermore, the strong vertical current caused by the sharp bathymetry gradient significantly weakens the stability in deep zones. In addition, this study assessed the impacts of rainfall and wind on lake stability using sensitivity analysis. The results indicated that rainfall decreases the water temperature of the lake but hardly affects the summer stratification. Moreover, the wind not only influences the intensity and duration of stratification but also contributes to the heat storage of waterbodies. The patterns of water current velocities and temperature also showed that the circulation generated by overflow and underflow plumes have a crucial effect on the Thermal Structure of the transition and lacustrine zones.
