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Gabriel Diniz - One of the best experts on this subject based on the ideXlab platform.
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evaluation of monte carlo tools for high energy Atmospheric Physics ii relativistic runaway electron avalanches
Geoscientific Model Development, 2018Co-Authors: D Sarria, Casper Rutjes, Alexander Broberg Skeltved, Alejandro Luque, Gabriel Diniz, N Ostgaard, Kevin M A Ihaddadene, J R Dwyer, I S FerreiraAbstract:Abstract. The emerging field of high-energy Atmospheric Physics studies how high-energy particles are produced in thunderstorms, in the form of terrestrial γ -ray flashes and γ -ray glows (also referred to as thunderstorm ground enhancements). Understanding these phenomena requires appropriate models of the interaction of electrons, positrons and photons with air molecules and electric fields. We investigated the results of three codes used in the community – Geant4, GRanada Relativistic Runaway simulator (GRRR) and Runaway Electron Avalanche Model (REAM) – to simulate relativistic runaway electron avalanches (RREAs). This work continues the study of Rutjes et al. ( 2016 ) , now also including the effects of uniform electric fields, up to the classical breakdown field, which is about 3.0 MV m −1 at standard temperature and pressure. We first present our theoretical description of the RREA process, which is based on and incremented over previous published works. This analysis confirmed that the avalanche is mainly driven by electric fields and the ionisation and scattering processes determining the minimum energy of electrons that can run away, which was found to be above ≈10 keV for any fields up to the classical breakdown field. To investigate this point further, we then evaluated the probability to produce a RREA as a function of the initial electron energy and of the magnitude of the electric field. We found that the stepping methodology in the particle simulation has to be set up very carefully in Geant4. For example, a too-large step size can lead to an avalanche probability reduced by a factor of 10 or to a 40 % overestimation of the average electron energy. When properly set up, both Geant4 models show an overall good agreement (within ≈10 %) with REAM and GRRR. Furthermore, the probability that particles below 10 keV accelerate and participate in the high-energy radiation is found to be negligible for electric fields below the classical breakdown value. The added value of accurately tracking low-energy particles ( keV) is minor and mainly visible for fields above 2 MV m −1 . In a second simulation set-up, we compared the physical characteristics of the avalanches produced by the four models: avalanche (time and length) scales, convergence time to a self-similar state and energy spectra of photons and electrons. The two Geant4 models and REAM showed good agreement on all parameters we tested. GRRR was also found to be consistent with the other codes, except for the electron energy spectra. That is probably because GRRR does not include straggling for the radiative and ionisation energy losses; hence, implementing these two processes is of primary importance to produce accurate RREA spectra. Including precise modelling of the interactions of particles below 10 keV (e.g. by taking into account molecular binding energy of secondary electrons for impact ionisation) also produced only small differences in the recorded spectra.
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evaluation of monte carlo tools for high energy Atmospheric Physics
Geoscientific Model Development, 2016Co-Authors: Casper Rutjes, D Sarria, Alexander Broberg Skeltved, Alejandro Luque, Gabriel Diniz, N Ostgaard, Ute EbertAbstract:Abstract. The emerging field of high energy Atmospheric Physics (HEAP) includes terrestrial gamma-ray flashes, electron–positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40 MeV energy with Atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of Physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy Atmospheric Physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100 keV and 40 MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50 keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.
Ute Ebert - One of the best experts on this subject based on the ideXlab platform.
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evaluation of monte carlo tools for high energy Atmospheric Physics
Geoscientific Model Development, 2016Co-Authors: Casper Rutjes, D Sarria, Alexander Broberg Skeltved, Alejandro Luque, Gabriel Diniz, N Ostgaard, Ute EbertAbstract:Abstract. The emerging field of high energy Atmospheric Physics (HEAP) includes terrestrial gamma-ray flashes, electron–positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40 MeV energy with Atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of Physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy Atmospheric Physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100 keV and 40 MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50 keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.
A V Eliseev - One of the best experts on this subject based on the ideXlab platform.
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impact of sulphur dioxide on the terrestrial carbon cycle
Izvestiya Atmospheric and Oceanic Physics, 2019Co-Authors: A V Eliseev, M Zhang, R D Gizatullin, A V Altukhova, Yu P Perevedentsev, A I SkorokhodAbstract:In this paper, the earlier results, which were obtained with the climate model developed at the A.M. Obu khov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM) and related to the impact of the Atmospheric sulphur dioxide on terrestrial carbon cycle, are elucidated. Because of the unavailability of the global data for near surface SO 2 concentration, it was reconstructed by using statistical model which was fitted employing the output of the Atmospheric chemistry-transport model RAMS-CMAQ. The obtained results are in general agreement with those reported earlier. In particular, the most significant SO 2 impact on terrestrial carbon cycle is simulated for south-east North America and for Europe. However, such impact for south-east Asia is markedly weaker in comparison to that reported earlier, which is related to excessive moisture content in the atmosphere of this region.
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impact of tropospheric sulphate aerosols on the terrestrial carbon cycle
Global and Planetary Change, 2015Co-Authors: A V EliseevAbstract:Tropospheric sulphate aerosols (TSAs) may oxidise the photosynthesising tissues if they are taken up by plants. A parameterisation of this impact of tropospheric sulphate aerosols (TSAs) on the terrestrial gross primary production is suggested. This parameterisation is implemented into the global Earth system model developed at the A.M. Obukhov Institute of the Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). With this coupled model, the simulations are performed which are forced by common anthropogenic and natural climate forcings based on historical reconstructions followed by the RCP 8.5 scenario. The model response to sulphate aerosol loading is subdivided into the climatic (related to the influence of TSA on the radiative transport in the atmosphere) and ecological (related to the toxic influence of sulphate aerosol on terrestrial plants) impacts. We found that the former basically dominates over the latter on a global scale and modifies the responses of the global vegetation and soil carbon stocks to external forcings by 10%. At a regional scale, however, ecological impact may be as much important as the climatic one.
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validating and assessing the sensitivity of the climate model with an ocean general circulation model developed at the institute of Atmospheric Physics russian academy of sciences
Izvestiya Atmospheric and Oceanic Physics, 2009Co-Authors: K E Muryshev, A V Eliseev, I I Mokhov, N A DianskyAbstract:A new version of the Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS), climate model (CM) has been developed using an ocean general circulation model instead of the statistical-dynamical ocean model applied in the previous version. The spatial resolution of the new ocean model is 3° in latitude and 5° in longitude, with 25 unevenly spaced vertical levels. In the previous version of the oceanic model, as in the Atmospheric model, the horizontal resolution was 4.5° in latitude and 6° in longitude, with four vertical levels (the upper quasi-homogeneous layer, seasonal thermocline, abyssal ocean, and bottom friction layer). There is no correction for the heat and momentum fluxes between the atmosphere and ocean in the new version of the IAP RAS CM. Numerical experiments with the IAP RAS CM have been performed under current initial and boundary conditions, as well as with an increasing concentration of Atmospheric carbon dioxide. The main simulated Atmospheric and oceanic fields agree quite well with observational data. The new version’s equilibrium temperature sensitivity to Atmospheric CO2 doubling was found to be 2.9 K. This value lies in the mid-range of estimates (2–4.5 K) obtained from simulations with state-of-the-art models of different complexities.
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simulation of characteristics of thermal and hydrologic soil regimes in equilibrium numerical experiments with a climate model of intermediate complexity
Izvestiya Atmospheric and Oceanic Physics, 2008Co-Authors: M M Arzhanov, P F Demchenko, A V Eliseev, I I MokhovAbstract:The IAP RAS CM (Institute of Atmospheric Physics, Russian Academy of Sciences, climate model) has been extended to include a comprehensive scheme of thermal and hydrologic soil processes. In equilibrium numerical experiments with specified preindustrial and current concentrations of Atmospheric carbon dioxide, the coupled model successfully reproduces thermal characteristics of soil, including the temperature of its surface, and seasonal thawing and freezing characteristics. On the whole, the model also reproduces soil hydrology, including the winter snow water equivalent and river runoff from large watersheds. Evapotranspiration from the soil surface and soil moisture are simulated somewhat worse. The equilibrium response of the model to a doubling of Atmospheric carbon dioxide shows a considerable warming of the soil surface, a reduction in the extent of permanently frozen soils, and the general growth of evaporation from continents. River runoff increases at high latitudes and decreases in the subtropics. The results are in qualitative agreement with observational data for the 20th century and with climate model simulations for the 21st century.
J C Pickering - One of the best experts on this subject based on the ideXlab platform.
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uv and vuv high resolution fourier transform spectroscopy laboratory atomic and molecular spectroscopy for astroPhysics and Atmospheric Physics applications
Fourier Transform Spectroscopy Hyperspectral Imaging and Sounding of the Environment (2005) paper FWA2, 2005Co-Authors: J C Pickering, D G Smillie, Richard Blackwellwhitehead, A P Thorne, J E Murray, Peter L SmithAbstract:Accurate new high-resolution UV and VUV atomic and molecular data for astroPhysics and Atmospheric Physics are needed. Extension of Fourier transform spectroscopy into the VUV at Imperial College is outlined, and laboratory spectroscopy applications described.
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high resolution fourier transform spectroscopy with the imperial college ic uv ft spectrometer and its applications to astroPhysics and Atmospheric Physics a review
Vibrational Spectroscopy, 2002Co-Authors: J C PickeringAbstract:Abstract The improvements in astronomical telescopes and their spectrographs, and in spectrographs used for studies of the earth’s atmosphere have created a requirement for matching improvements in the laboratory atomic and molecular database needed in the analysis of the astrophysical and Atmospheric spectra. The technique of Fourier transform spectroscopy (FTS) is described and its suitability in improving the atomic and molecular databases is discussed. The extension of the wavelength range of the Fourier transform (FT) spectrometry into the vacuum ultraviolet to 140 nm is described. Examples are given of recent atomic and molecular spectroscopy research using the Imperial College (IC) UV-FT spectrometer and applications to astroPhysics and Atmospheric Physics are given.
Casper Rutjes - One of the best experts on this subject based on the ideXlab platform.
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evaluation of monte carlo tools for high energy Atmospheric Physics ii relativistic runaway electron avalanches
Geoscientific Model Development, 2018Co-Authors: D Sarria, Casper Rutjes, Alexander Broberg Skeltved, Alejandro Luque, Gabriel Diniz, N Ostgaard, Kevin M A Ihaddadene, J R Dwyer, I S FerreiraAbstract:Abstract. The emerging field of high-energy Atmospheric Physics studies how high-energy particles are produced in thunderstorms, in the form of terrestrial γ -ray flashes and γ -ray glows (also referred to as thunderstorm ground enhancements). Understanding these phenomena requires appropriate models of the interaction of electrons, positrons and photons with air molecules and electric fields. We investigated the results of three codes used in the community – Geant4, GRanada Relativistic Runaway simulator (GRRR) and Runaway Electron Avalanche Model (REAM) – to simulate relativistic runaway electron avalanches (RREAs). This work continues the study of Rutjes et al. ( 2016 ) , now also including the effects of uniform electric fields, up to the classical breakdown field, which is about 3.0 MV m −1 at standard temperature and pressure. We first present our theoretical description of the RREA process, which is based on and incremented over previous published works. This analysis confirmed that the avalanche is mainly driven by electric fields and the ionisation and scattering processes determining the minimum energy of electrons that can run away, which was found to be above ≈10 keV for any fields up to the classical breakdown field. To investigate this point further, we then evaluated the probability to produce a RREA as a function of the initial electron energy and of the magnitude of the electric field. We found that the stepping methodology in the particle simulation has to be set up very carefully in Geant4. For example, a too-large step size can lead to an avalanche probability reduced by a factor of 10 or to a 40 % overestimation of the average electron energy. When properly set up, both Geant4 models show an overall good agreement (within ≈10 %) with REAM and GRRR. Furthermore, the probability that particles below 10 keV accelerate and participate in the high-energy radiation is found to be negligible for electric fields below the classical breakdown value. The added value of accurately tracking low-energy particles ( keV) is minor and mainly visible for fields above 2 MV m −1 . In a second simulation set-up, we compared the physical characteristics of the avalanches produced by the four models: avalanche (time and length) scales, convergence time to a self-similar state and energy spectra of photons and electrons. The two Geant4 models and REAM showed good agreement on all parameters we tested. GRRR was also found to be consistent with the other codes, except for the electron energy spectra. That is probably because GRRR does not include straggling for the radiative and ionisation energy losses; hence, implementing these two processes is of primary importance to produce accurate RREA spectra. Including precise modelling of the interactions of particles below 10 keV (e.g. by taking into account molecular binding energy of secondary electrons for impact ionisation) also produced only small differences in the recorded spectra.
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evaluation of monte carlo tools for high energy Atmospheric Physics
Geoscientific Model Development, 2016Co-Authors: Casper Rutjes, D Sarria, Alexander Broberg Skeltved, Alejandro Luque, Gabriel Diniz, N Ostgaard, Ute EbertAbstract:Abstract. The emerging field of high energy Atmospheric Physics (HEAP) includes terrestrial gamma-ray flashes, electron–positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40 MeV energy with Atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of Physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy Atmospheric Physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100 keV and 40 MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50 keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.