The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
David K Sing - One of the best experts on this subject based on the ideXlab platform.
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fully scalable Forward Model grid of exoplanet transmission spectra
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Jayesh Goyal, Hannah R Wakeford, N J Mayne, Nikole K Lewis, Benjamin Drummond, David K SingAbstract:Simulated exoplanet transmission spectra are critical for planning and interpretation of observations and to explore the sensitivity of spectral features to atmospheric thermochemical processes. We present a publicly available generic Model grid of planetary transmission spectra, scalable to a wide range of H$_2$/He dominated atmospheres. The grid is computed using the 1D/2D atmosphere Model ATMO for two different chemical scenarios, first considering local condensation only, secondly considering global condensation and removal of species from the atmospheric column (rainout). The entire grid consists of 56,320 Model simulations across 22 equilibrium temperatures (400 - 2600 K), four planetary gravities (5 - 50 ms$^{-2}$), five atmospheric metallicities (1x - 200x), four C/O ratios (0.35 - 1.0), four scattering haze parameters, four uniform cloud parameters, and two chemical scenarios. We derive scaling equations which can be used with this grid, for a wide range of planet-star combinations. We validate this grid by comparing it with other Model transmission spectra available in the literature. We highlight some of the important findings, such as the rise of SO$_2$ features at 100x solar metallicity, differences in spectral features at high C/O ratios between two condensation approaches, the importance of VO features without TiO to constrain the limb temperature and features of TiO/VO both, to constrain the condensation processes. Finally, this generic grid can be used to plan future observations using the HST, VLT, JWST and various other telescopes. The fine variation of parameters in the grid also allows it to be incorporated in a retrieval framework, with various machine learning techniques.
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a library of atmo Forward Model transmission spectra for hot jupiter exoplanets
Monthly Notices of the Royal Astronomical Society, 2018Co-Authors: Jayesh Goyal, N J Mayne, Benjamin Drummond, David K Sing, P Tremblin, David S Amundsen, Thomas M Evans, Aarynn L Carter, J SpakeAbstract:J.M.G and N.M are part funded by a Leverhulme Trust Research Project Grant, and in part by a University of Exeter College of Engineering, Mathematics and Physical Sciences PhD studentship. D.K.S, T.E, N.N acknowledges support from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007- 2013)/ ERC grant agreement number 336792. B.D. thanks the University of Exeter for support through a Ph.D. studentship. D.S.A. acknowledges support from the NASA Astrobiology Program through the Nexus for Exoplanet System Science.This work used the DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility. This work also used the University of Exeter Supercomputer, a DiRAC Facility jointly funded by STFC, the Large Facilities Capital Fund of BIS and the University of Exeter.
Jayesh Goyal - One of the best experts on this subject based on the ideXlab platform.
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fully scalable Forward Model grid of exoplanet transmission spectra
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Jayesh Goyal, Hannah R Wakeford, N J Mayne, Nikole K Lewis, Benjamin Drummond, David K SingAbstract:Simulated exoplanet transmission spectra are critical for planning and interpretation of observations and to explore the sensitivity of spectral features to atmospheric thermochemical processes. We present a publicly available generic Model grid of planetary transmission spectra, scalable to a wide range of H$_2$/He dominated atmospheres. The grid is computed using the 1D/2D atmosphere Model ATMO for two different chemical scenarios, first considering local condensation only, secondly considering global condensation and removal of species from the atmospheric column (rainout). The entire grid consists of 56,320 Model simulations across 22 equilibrium temperatures (400 - 2600 K), four planetary gravities (5 - 50 ms$^{-2}$), five atmospheric metallicities (1x - 200x), four C/O ratios (0.35 - 1.0), four scattering haze parameters, four uniform cloud parameters, and two chemical scenarios. We derive scaling equations which can be used with this grid, for a wide range of planet-star combinations. We validate this grid by comparing it with other Model transmission spectra available in the literature. We highlight some of the important findings, such as the rise of SO$_2$ features at 100x solar metallicity, differences in spectral features at high C/O ratios between two condensation approaches, the importance of VO features without TiO to constrain the limb temperature and features of TiO/VO both, to constrain the condensation processes. Finally, this generic grid can be used to plan future observations using the HST, VLT, JWST and various other telescopes. The fine variation of parameters in the grid also allows it to be incorporated in a retrieval framework, with various machine learning techniques.
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a library of atmo Forward Model transmission spectra for hot jupiter exoplanets
Monthly Notices of the Royal Astronomical Society, 2018Co-Authors: Jayesh Goyal, N J Mayne, Benjamin Drummond, David K Sing, P Tremblin, David S Amundsen, Thomas M Evans, Aarynn L Carter, J SpakeAbstract:J.M.G and N.M are part funded by a Leverhulme Trust Research Project Grant, and in part by a University of Exeter College of Engineering, Mathematics and Physical Sciences PhD studentship. D.K.S, T.E, N.N acknowledges support from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007- 2013)/ ERC grant agreement number 336792. B.D. thanks the University of Exeter for support through a Ph.D. studentship. D.S.A. acknowledges support from the NASA Astrobiology Program through the Nexus for Exoplanet System Science.This work used the DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility. This work also used the University of Exeter Supercomputer, a DiRAC Facility jointly funded by STFC, the Large Facilities Capital Fund of BIS and the University of Exeter.
Benjamin Drummond - One of the best experts on this subject based on the ideXlab platform.
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fully scalable Forward Model grid of exoplanet transmission spectra
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Jayesh Goyal, Hannah R Wakeford, N J Mayne, Nikole K Lewis, Benjamin Drummond, David K SingAbstract:Simulated exoplanet transmission spectra are critical for planning and interpretation of observations and to explore the sensitivity of spectral features to atmospheric thermochemical processes. We present a publicly available generic Model grid of planetary transmission spectra, scalable to a wide range of H$_2$/He dominated atmospheres. The grid is computed using the 1D/2D atmosphere Model ATMO for two different chemical scenarios, first considering local condensation only, secondly considering global condensation and removal of species from the atmospheric column (rainout). The entire grid consists of 56,320 Model simulations across 22 equilibrium temperatures (400 - 2600 K), four planetary gravities (5 - 50 ms$^{-2}$), five atmospheric metallicities (1x - 200x), four C/O ratios (0.35 - 1.0), four scattering haze parameters, four uniform cloud parameters, and two chemical scenarios. We derive scaling equations which can be used with this grid, for a wide range of planet-star combinations. We validate this grid by comparing it with other Model transmission spectra available in the literature. We highlight some of the important findings, such as the rise of SO$_2$ features at 100x solar metallicity, differences in spectral features at high C/O ratios between two condensation approaches, the importance of VO features without TiO to constrain the limb temperature and features of TiO/VO both, to constrain the condensation processes. Finally, this generic grid can be used to plan future observations using the HST, VLT, JWST and various other telescopes. The fine variation of parameters in the grid also allows it to be incorporated in a retrieval framework, with various machine learning techniques.
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a library of atmo Forward Model transmission spectra for hot jupiter exoplanets
Monthly Notices of the Royal Astronomical Society, 2018Co-Authors: Jayesh Goyal, N J Mayne, Benjamin Drummond, David K Sing, P Tremblin, David S Amundsen, Thomas M Evans, Aarynn L Carter, J SpakeAbstract:J.M.G and N.M are part funded by a Leverhulme Trust Research Project Grant, and in part by a University of Exeter College of Engineering, Mathematics and Physical Sciences PhD studentship. D.K.S, T.E, N.N acknowledges support from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007- 2013)/ ERC grant agreement number 336792. B.D. thanks the University of Exeter for support through a Ph.D. studentship. D.S.A. acknowledges support from the NASA Astrobiology Program through the Nexus for Exoplanet System Science.This work used the DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility. This work also used the University of Exeter Supercomputer, a DiRAC Facility jointly funded by STFC, the Large Facilities Capital Fund of BIS and the University of Exeter.
N J Mayne - One of the best experts on this subject based on the ideXlab platform.
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fully scalable Forward Model grid of exoplanet transmission spectra
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Jayesh Goyal, Hannah R Wakeford, N J Mayne, Nikole K Lewis, Benjamin Drummond, David K SingAbstract:Simulated exoplanet transmission spectra are critical for planning and interpretation of observations and to explore the sensitivity of spectral features to atmospheric thermochemical processes. We present a publicly available generic Model grid of planetary transmission spectra, scalable to a wide range of H$_2$/He dominated atmospheres. The grid is computed using the 1D/2D atmosphere Model ATMO for two different chemical scenarios, first considering local condensation only, secondly considering global condensation and removal of species from the atmospheric column (rainout). The entire grid consists of 56,320 Model simulations across 22 equilibrium temperatures (400 - 2600 K), four planetary gravities (5 - 50 ms$^{-2}$), five atmospheric metallicities (1x - 200x), four C/O ratios (0.35 - 1.0), four scattering haze parameters, four uniform cloud parameters, and two chemical scenarios. We derive scaling equations which can be used with this grid, for a wide range of planet-star combinations. We validate this grid by comparing it with other Model transmission spectra available in the literature. We highlight some of the important findings, such as the rise of SO$_2$ features at 100x solar metallicity, differences in spectral features at high C/O ratios between two condensation approaches, the importance of VO features without TiO to constrain the limb temperature and features of TiO/VO both, to constrain the condensation processes. Finally, this generic grid can be used to plan future observations using the HST, VLT, JWST and various other telescopes. The fine variation of parameters in the grid also allows it to be incorporated in a retrieval framework, with various machine learning techniques.
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a library of atmo Forward Model transmission spectra for hot jupiter exoplanets
Monthly Notices of the Royal Astronomical Society, 2018Co-Authors: Jayesh Goyal, N J Mayne, Benjamin Drummond, David K Sing, P Tremblin, David S Amundsen, Thomas M Evans, Aarynn L Carter, J SpakeAbstract:J.M.G and N.M are part funded by a Leverhulme Trust Research Project Grant, and in part by a University of Exeter College of Engineering, Mathematics and Physical Sciences PhD studentship. D.K.S, T.E, N.N acknowledges support from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007- 2013)/ ERC grant agreement number 336792. B.D. thanks the University of Exeter for support through a Ph.D. studentship. D.S.A. acknowledges support from the NASA Astrobiology Program through the Nexus for Exoplanet System Science.This work used the DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility. This work also used the University of Exeter Supercomputer, a DiRAC Facility jointly funded by STFC, the Large Facilities Capital Fund of BIS and the University of Exeter.
Michael N. Evans - One of the best experts on this subject based on the ideXlab platform.
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comparison of observed and simulated tropical climate trends using a Forward Model of coral δ18o
Geophysical Research Letters, 2011Co-Authors: D M Thompson, Michael N. Evans, Toby R Ault, Julia E Cole, Julien EmilegeayAbstract:[1] The response of the tropical Pacific Ocean to future climate change remains highly uncertain, in part because of the disagreement among observations and coupled general circulation Models (CGCMs) regarding 20th-century trends. Here we use Forward Models of climate proxies to compare CGCM simulations and proxy observations to address 20th-century trends and assess remaining uncertainties in both proxies and Models. We Model coral oxygen isotopic composition (δ 18O) in a 23-site Indo-Pacific network as a linear function of sea-surface temperature (SST) and sea-surface salinity (SSS) obtained from historical marine observations (instrumental data) and a multiModel ensemble of 20th-century CGCM output. When driven with instrumental data from 1958 to 1990, the Forward Modeled corals (pseudocorals) capture the spatial pattern and temporal evolution of the El Nino-Southern Oscillation (ENSO). Comparison of the linear trend observed in corals and instrumental pseudocorals suggests that the trend in corals between 1958 and 1990 results from both warming (60%) and freshening (40%). From 1890 to 1990, the warming/freshening trend in CGCM pseudocorals is weaker than that observed in corals. Corals display a moderate trend towards a reduced zonal SST gradient and decreased ENSO-related variance between 1895 and 1985, whereas CGCM pseudocorals display a range of trend patterns and an increase in ENSO-related variance over the same period. Differences between corals and CGCM pseudocorals may arise from uncertainties in the linear bivariate coral Model, uncertainties in the way corals record climate, undersensitivity of CGCMs to radiative forcing during the 20th century, and/or biases in the simulated CGCM SSS fields.
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an efficient Forward Model of the climate controls on interannual variation in tree ring width
Climate Dynamics, 2011Co-Authors: S E Tolwinskiward, Michael N. Evans, Malcolm K. Hughes, Kanchuka J. AnchukaitisAbstract:We present a simple, efficient, process-based Forward Model of tree-ring growth, called Vaganov–Shashkin-Lite (VS-Lite), that requires as inputs only latitude and monthly temperature and precipitation. Simulations of six bristlecone pine ring-width chronologies demonstrate the interpretability of Model output as an accurate representation of the climatic controls on growth. Ensemble simulations by VS-Lite of two networks of North American ring-width chronologies correlate with observations at higher significance levels on average than simulations formed by regression of ring width on the principal components of the same monthly climate data. VS-Lite retains more skill outside of calibration intervals than does the principal components regression approach. It captures the dominant low- and high-frequency spatiotemporal ring-width signals in the network with an inhomogeneous, multivariate relationship to climate. Because continuous meteorological data are most widely available at monthly temporal resolution, our Model extends the set of sites at which Forward-Modeling studies are possible. Other potential uses of VS-Lite include generation of synthetic ring-width series for pseudo-proxy studies, as a data level Model in data assimilation-based climate reconstructions, and for bias estimation in actual ring-width index series.
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a Forward Modeling approach to paleoclimatic interpretation of tree ring data
Journal of Geophysical Research, 2006Co-Authors: Michael N. Evans, Bernhard K. Reichert, Alexey Kaplan, Kanchuka J. Anchukaitis, Eugene A. Vaganov, Malcolm K. Hughes, Mark A. CaneAbstract:[1] We investigate the interpretation of tree-ring data using the Vaganov-Shashkin Forward Model of tree-ring formation. This Model is derived from principles of conifer wood growth, and explicitly incorporates a nonlinear daily timescale Model of the multivariate environmental controls on tree-ring growth. The Model results are shown to be robust with respect to primary moisture and temperature parameter choices. When applied to the simulation of tree-ring widths from North America and Russia from the Mann et al. (1998) and Vaganov et al. (2006) data sets, the Forward Model produces skill on annual and decadal timescales which is about the same as that achieved using classical dendrochronological statistical Modeling techniques. The Forward Model achieves this without site-by-site tuning as is performed in statistical Modeling. The results support the interpretation of this broad-scale network of tree-ring width chronologies primarily as climate proxies for use in statistical paleoclimatic field reconstructions, and point to further applications in climate science.
