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Paulo A Silva - One of the best experts on this subject based on the ideXlab platform.
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improving the Parameterization of wave nonlinearities the importance of wave steepness spectral bandwidth and beach slope
Coastal Engineering, 2017Co-Authors: Mariana Vieira Lima Matias Da Rocha, Herve Michallet, Paulo A SilvaAbstract:Abstract Wave-velocity nonlinearities are among the main drivers of sediment transport. For practical engineering purposes, they can be described by simple Parameterizations that allow their easier inclusion in nearshore morphodynamic models. Most existing Parameterizations propose the estimation of velocity nonlinearities only from local wave parameters (such as the Ursell number). Herein, it is demonstrated that this provides inaccurate estimations of the wave nonlinearities. Furthermore, the effect of offshore wave steepness, offshore spectral bandwidth and beach slope on the velocity nonlinearities is shown to be sufficiently important to merit its inclusion in the existing Parameterizations. Ruessink et al. (2012) [28] Parameterization is modified in order to include both offshore spectral bandwidth and a new parameter, NP 0 , which takes into account the beach slope and the squared offshore wave steepness. The new Parameterization results in a reduction of the wave-nonlinearities estimation error of more than 50%, particularly for the maximum values of nonlinearity (near breaking) that contribute the most for sediment transport.
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Improving the Parameterization of wave nonlinearities – The importance of wave steepness, spectral bandwidth and beach slope
Coastal Engineering, 2017Co-Authors: Mariana Vieira Lima Matias Da Rocha, Herve Michallet, Paulo A SilvaAbstract:Abstract Wave-velocity nonlinearities are among the main drivers of sediment transport. For practical engineering purposes, they can be described by simple Parameterizations that allow their easier inclusion in nearshore morphodynamic models. Most existing Parameterizations propose the estimation of velocity nonlinearities only from local wave parameters (such as the Ursell number). Herein, it is demonstrated that this provides inaccurate estimations of the wave nonlinearities. Furthermore, the effect of offshore wave steepness, offshore spectral bandwidth and beach slope on the velocity nonlinearities is shown to be sufficiently important to merit its inclusion in the existing Parameterizations. Ruessink et al. (2012) [28] Parameterization is modified in order to include both offshore spectral bandwidth and a new parameter, NP 0 , which takes into account the beach slope and the squared offshore wave steepness. The new Parameterization results in a reduction of the wave-nonlinearities estimation error of more than 50%, particularly for the maximum values of nonlinearity (near breaking) that contribute the most for sediment transport.
Mariana Vieira Lima Matias Da Rocha - One of the best experts on this subject based on the ideXlab platform.
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improving the Parameterization of wave nonlinearities the importance of wave steepness spectral bandwidth and beach slope
Coastal Engineering, 2017Co-Authors: Mariana Vieira Lima Matias Da Rocha, Herve Michallet, Paulo A SilvaAbstract:Abstract Wave-velocity nonlinearities are among the main drivers of sediment transport. For practical engineering purposes, they can be described by simple Parameterizations that allow their easier inclusion in nearshore morphodynamic models. Most existing Parameterizations propose the estimation of velocity nonlinearities only from local wave parameters (such as the Ursell number). Herein, it is demonstrated that this provides inaccurate estimations of the wave nonlinearities. Furthermore, the effect of offshore wave steepness, offshore spectral bandwidth and beach slope on the velocity nonlinearities is shown to be sufficiently important to merit its inclusion in the existing Parameterizations. Ruessink et al. (2012) [28] Parameterization is modified in order to include both offshore spectral bandwidth and a new parameter, NP 0 , which takes into account the beach slope and the squared offshore wave steepness. The new Parameterization results in a reduction of the wave-nonlinearities estimation error of more than 50%, particularly for the maximum values of nonlinearity (near breaking) that contribute the most for sediment transport.
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Improving the Parameterization of wave nonlinearities – The importance of wave steepness, spectral bandwidth and beach slope
Coastal Engineering, 2017Co-Authors: Mariana Vieira Lima Matias Da Rocha, Herve Michallet, Paulo A SilvaAbstract:Abstract Wave-velocity nonlinearities are among the main drivers of sediment transport. For practical engineering purposes, they can be described by simple Parameterizations that allow their easier inclusion in nearshore morphodynamic models. Most existing Parameterizations propose the estimation of velocity nonlinearities only from local wave parameters (such as the Ursell number). Herein, it is demonstrated that this provides inaccurate estimations of the wave nonlinearities. Furthermore, the effect of offshore wave steepness, offshore spectral bandwidth and beach slope on the velocity nonlinearities is shown to be sufficiently important to merit its inclusion in the existing Parameterizations. Ruessink et al. (2012) [28] Parameterization is modified in order to include both offshore spectral bandwidth and a new parameter, NP 0 , which takes into account the beach slope and the squared offshore wave steepness. The new Parameterization results in a reduction of the wave-nonlinearities estimation error of more than 50%, particularly for the maximum values of nonlinearity (near breaking) that contribute the most for sediment transport.
Nicola J Blake - One of the best experts on this subject based on the ideXlab platform.
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transport of radon 222 and methyl iodide by deep convection in the gfdl global atmospheric model am2
Journal of Geophysical Research, 2007Co-Authors: Leo J Donner, Larry W Horowitz, Arlene M Fiore, Charles J Seman, D R Blake, Nicola J BlakeAbstract:Author(s): Donner, LJ; Horowitz, LW; Fiore, AM; Seman, CJ; Blake, DR; Blake, NJ | Abstract: Transport of radon-222 and methyl iodide by deep convection is analyzed in the Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model 2 (AM2) using two Parameterizations for deep convection. One of these Parameterizations represents deep convection as an ensemble of entraining plumes; the other represents deep convection as an ensemble of entraining plumes with associated mesoscale updrafts and downdrafts. Although precipitation patterns are generally similar in AM2 with both Parameterizations, the deep convective mass fluxes are more than three times larger in the middle- to upper troposphere for the Parameterization consisting only of entraining plumes, but do not extend across the tropopause, unlike the Parameterization including mesoscale circulations. The differences in mass fluxes result mainly from a different partitioning between convective and stratiform precipitation; the Parameterization including mesoscale circulations detrains considerably more water vapor in the middle troposphere and is associated with more stratiform rain. The distributions of both radon-222 and methyl iodide reflect the different mass fluxes. Relative to observations (limited by infrequent spatial and temporal sampling), AM2 tends to simulate lower concentrations of radon-222 and methyl iodide in the planetary boundary layer, producing a negative model bias through much of the troposphere, with both cumulus Parameterizations. The shapes of the observed profiles suggest that the larger deep convective mass fluxes and associated transport in the Parameterization lacking a mesoscale component are less realistic. Copyright 2007 by the American Geophysical Union.
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Transport of radon‐222 and methyl iodide by deep convection in the GFDL Global Atmospheric Model AM2
Journal of Geophysical Research, 2007Co-Authors: Leo J Donner, Larry W Horowitz, Arlene M Fiore, Charles J Seman, D R Blake, Nicola J BlakeAbstract:Author(s): Donner, LJ; Horowitz, LW; Fiore, AM; Seman, CJ; Blake, DR; Blake, NJ | Abstract: Transport of radon-222 and methyl iodide by deep convection is analyzed in the Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model 2 (AM2) using two Parameterizations for deep convection. One of these Parameterizations represents deep convection as an ensemble of entraining plumes; the other represents deep convection as an ensemble of entraining plumes with associated mesoscale updrafts and downdrafts. Although precipitation patterns are generally similar in AM2 with both Parameterizations, the deep convective mass fluxes are more than three times larger in the middle- to upper troposphere for the Parameterization consisting only of entraining plumes, but do not extend across the tropopause, unlike the Parameterization including mesoscale circulations. The differences in mass fluxes result mainly from a different partitioning between convective and stratiform precipitation; the Parameterization including mesoscale circulations detrains considerably more water vapor in the middle troposphere and is associated with more stratiform rain. The distributions of both radon-222 and methyl iodide reflect the different mass fluxes. Relative to observations (limited by infrequent spatial and temporal sampling), AM2 tends to simulate lower concentrations of radon-222 and methyl iodide in the planetary boundary layer, producing a negative model bias through much of the troposphere, with both cumulus Parameterizations. The shapes of the observed profiles suggest that the larger deep convective mass fluxes and associated transport in the Parameterization lacking a mesoscale component are less realistic. Copyright 2007 by the American Geophysical Union.
Graham D Farquhar - One of the best experts on this subject based on the ideXlab platform.
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revisiting the Parameterization of potential evaporation as a driver of long term water balance trends
Geophysical Research Letters, 2008Co-Authors: Michael T Hobbins, Michael L Roderick, Graham D FarquharAbstract:[1] We examine the effects of two different Parameterizations of potential evaporation on long-term trends in soil moisture, evaporative flux and runoff simulated by the water balance model underlying the Palmer Drought Severity Index. The first, traditional Parameterization is based on air temperature alone. The second Parameterization is derived from observations of evaporation from class-A pans. Trends in potential evaporation from the two Parameterizations are opposite in sign (±) at almost half the stations tested over Australia and New Zealand. The sign of trends in the modelled soil moisture, evaporative flux and runoff depends on the Parameterization used and on the prevailing climatic regime: trends in water-limited regions are driven by precipitation trends, but the choice of Parameterization for potential evaporation is shown to be critical in energy-limited regions.
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Revisiting the Parameterization of potential evaporation as a driver of long‐term water balance trends
Geophysical Research Letters, 2008Co-Authors: Michael T Hobbins, Michael L Roderick, Graham D FarquharAbstract:[1] We examine the effects of two different Parameterizations of potential evaporation on long-term trends in soil moisture, evaporative flux and runoff simulated by the water balance model underlying the Palmer Drought Severity Index. The first, traditional Parameterization is based on air temperature alone. The second Parameterization is derived from observations of evaporation from class-A pans. Trends in potential evaporation from the two Parameterizations are opposite in sign (±) at almost half the stations tested over Australia and New Zealand. The sign of trends in the modelled soil moisture, evaporative flux and runoff depends on the Parameterization used and on the prevailing climatic regime: trends in water-limited regions are driven by precipitation trends, but the choice of Parameterization for potential evaporation is shown to be critical in energy-limited regions.
Leo J Donner - One of the best experts on this subject based on the ideXlab platform.
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transport of radon 222 and methyl iodide by deep convection in the gfdl global atmospheric model am2
Journal of Geophysical Research, 2007Co-Authors: Leo J Donner, Larry W Horowitz, Arlene M Fiore, Charles J Seman, D R Blake, Nicola J BlakeAbstract:Author(s): Donner, LJ; Horowitz, LW; Fiore, AM; Seman, CJ; Blake, DR; Blake, NJ | Abstract: Transport of radon-222 and methyl iodide by deep convection is analyzed in the Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model 2 (AM2) using two Parameterizations for deep convection. One of these Parameterizations represents deep convection as an ensemble of entraining plumes; the other represents deep convection as an ensemble of entraining plumes with associated mesoscale updrafts and downdrafts. Although precipitation patterns are generally similar in AM2 with both Parameterizations, the deep convective mass fluxes are more than three times larger in the middle- to upper troposphere for the Parameterization consisting only of entraining plumes, but do not extend across the tropopause, unlike the Parameterization including mesoscale circulations. The differences in mass fluxes result mainly from a different partitioning between convective and stratiform precipitation; the Parameterization including mesoscale circulations detrains considerably more water vapor in the middle troposphere and is associated with more stratiform rain. The distributions of both radon-222 and methyl iodide reflect the different mass fluxes. Relative to observations (limited by infrequent spatial and temporal sampling), AM2 tends to simulate lower concentrations of radon-222 and methyl iodide in the planetary boundary layer, producing a negative model bias through much of the troposphere, with both cumulus Parameterizations. The shapes of the observed profiles suggest that the larger deep convective mass fluxes and associated transport in the Parameterization lacking a mesoscale component are less realistic. Copyright 2007 by the American Geophysical Union.
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Transport of radon‐222 and methyl iodide by deep convection in the GFDL Global Atmospheric Model AM2
Journal of Geophysical Research, 2007Co-Authors: Leo J Donner, Larry W Horowitz, Arlene M Fiore, Charles J Seman, D R Blake, Nicola J BlakeAbstract:Author(s): Donner, LJ; Horowitz, LW; Fiore, AM; Seman, CJ; Blake, DR; Blake, NJ | Abstract: Transport of radon-222 and methyl iodide by deep convection is analyzed in the Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model 2 (AM2) using two Parameterizations for deep convection. One of these Parameterizations represents deep convection as an ensemble of entraining plumes; the other represents deep convection as an ensemble of entraining plumes with associated mesoscale updrafts and downdrafts. Although precipitation patterns are generally similar in AM2 with both Parameterizations, the deep convective mass fluxes are more than three times larger in the middle- to upper troposphere for the Parameterization consisting only of entraining plumes, but do not extend across the tropopause, unlike the Parameterization including mesoscale circulations. The differences in mass fluxes result mainly from a different partitioning between convective and stratiform precipitation; the Parameterization including mesoscale circulations detrains considerably more water vapor in the middle troposphere and is associated with more stratiform rain. The distributions of both radon-222 and methyl iodide reflect the different mass fluxes. Relative to observations (limited by infrequent spatial and temporal sampling), AM2 tends to simulate lower concentrations of radon-222 and methyl iodide in the planetary boundary layer, producing a negative model bias through much of the troposphere, with both cumulus Parameterizations. The shapes of the observed profiles suggest that the larger deep convective mass fluxes and associated transport in the Parameterization lacking a mesoscale component are less realistic. Copyright 2007 by the American Geophysical Union.
