The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Manuel López-puertas - One of the best experts on this subject based on the ideXlab platform.
-
RADIATION TRANSFER IN THE ATMOSPHERE | Non-Local Thermodynamic Equilibrium
Encyclopedia of Atmospheric Sciences, 2015Co-Authors: Manuel López-puertas, Bernd FunkeAbstract:This article introduces the concept of non-Local Thermodynamic Equilibrium (non-LTE) in planetary atmospheres and provides a basic theoretical framework of non-LTE radiative transfer and statistical Equilibrium of molecular states. Accurate and approximate solutions of the non-LTE problem are discussed. A climatology of non-LTE populations of the most important vibrational levels of the atmospheric species is provided. Examples of non-LTE applications in general circulation models and the remote sensing of the Earth's and other planetary atmospheres are given.
-
Evidence for N2O ν3 4.5 μm non‐Local Thermodynamic Equilibrium emission in the atmosphere
Geophysical Research Letters, 2007Co-Authors: Manuel López-puertas, T. Von Clarmann, Bernd Funke, Udo Grabowski, G. P. Stiller, D. Bermejo-pantaleón, Michael HöpfnerAbstract:[1] We present a clear evidence for N2O 4.5 μm non-Local Thermodynamic Equilibrium (non-LTE) emissions in the daylight stratosphere and mesosphere from measurements by the MIPAS experiment on board Envisat. We have used non-LTE radiative transfer models in order to quantify the magnitude and extent of the non-LTE deviation of N2O(001) in the Earth's atmosphere. The departure from LTE in N2O during daytime commences at altitudes around 40–50 km, but have significant effects (10%) on daytime limb radiance down to tangent heights of 20 km. The enhancement increases rapidly with altitude, being 20–80% at 50 km, and reaching factors of 2–8 in the lower mesosphere. This study shows that the enhancement is mainly produced by absorption of solar radiation by N2O at 4.5 μm and by V-V collisions with N2(1). Non-LTE effects are also significant at nighttime, where LTE calculations overpredict N2O radiances by 10–20% at 40–55 km tangent heights.
-
Evidence for CH4 7.6 μm non‐Local Thermodynamic Equilibrium emission in the mesosphere
Geophysical Research Letters, 2005Co-Authors: Manuel López-puertas, T. Von Clarmann, Bernd Funke, Maria-elissavet Koukouli, Sergio Gil-lopez, Norbert Glatthor, Udo Grabowski, G. P. StillerAbstract:[1] We present unequivocal evidence for CH4 7.6 μm non-Local Thermodynamic Equilibrium (non-LTE) mesospheric emissions as measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ESA Envisat satellite. We have employed non-LTE radiative transfer models, already used and validated in studies of other atmospheric gases, in order to quantify the magnitude and extent of the CH4 non-LTE deviation in the Earth's atmosphere. The observed daytime enhancement signatures apparent in the measured radiances cannot be attributed to enhanced daytime temperatures and/or CH4 abundance variations and are reproduced successfully with a dedicated CH4 non-LTE radiative transfer model. We conclude that, depending on the upper stratospheric/mesospheric temperature structure, the departure from LTE might commence at an altitude as low as 45 km, reaching limb radiance deviations of 20% at 60 km and quickly rising up to 60% at 70 km, for the 7.6 μm CH4 lines.
-
Intercomparison of radiative transfer codes under non-Local Thermodynamic Equilibrium conditions
Journal of Geophysical Research, 2002Co-Authors: T. Von Clarmann, Anu Dudhia, David P. Edwards, Bernd Funke, Michael Höpfner, Brian Kerridge, V. S. Kostsov, Andrea Linden, Manuel López-puertas, Yu. M. TimofeyevAbstract:[1] Limb infrared spectra calculated by the Optimized and Precise Radiative Transfer Algorithm (KOPRA), GENLN2, Reference Forward Model (RFM), and Simulation Program for Infrared Radiative Transfer (SPIRT) radiative transfer algorithms were intercompared for both Local Thermodynamic Equilibrium (LTE) and non-Local Thermodynamic Equilibrium (non-LTE) conditions, in the latter case for given profiles of vibrational temperatures. The overall agreement is usually better than approximately 0.5%, except for isolated phenomena that have been assessed in more detail. Most spectral radiance discrepancies occur also under LTE conditions and are attributed to different treatment of far wings of lines, integration schemes, and mass-weighted averaging of atmospheric temperature and pressure along slant path segments as well as different spectral sampling during the calculation of monochromatic radiances.
-
Non‐Local Thermodynamic Equilibrium in general circulation models of the Martian atmosphere 1. Effects of the Local Thermodynamic Equilibrium approximation on thermal cooling and solar heating
Journal of Geophysical Research: Planets, 1998Co-Authors: Miguel Lopez-valverde, David P. Edwards, Manuel López-puertas, Cristina RoldánAbstract:Calculations of CO2 thermal cooling and near-IR solar heating rates under non-Local Thermodynamic Equilibrium (non-LTE) situations have been performed to understand and evaluate the effects of non-LTE on the energy balance of the upper atmosphere of Mars. We find that the 15-μm cooling rates can be in error if LTE is assumed above 80 km. In general, the correct non-LTE values are significantly smaller than the LTE values above about 85 km, but the magnitude and sign of the error depend on the temperature structure and the top altitude of the model and, to a lesser extent, on the collisions with atomic oxygen. A detailed analysis of the relevance of the upper boundary layer and a suggested buffer region are presented for both LTE and non-LTE. Based on general considerations of the thermal profile in the mesosphere and lower thermosphere, recommendations for general circulation models (GCM) are presented as a first guide for minimizing the LTE cooling rates inaccuracies. The error of assuming LTE on the CO2 near-IR solar heating rates is found to be about 20% at 85 km and increases strongly above this altitude. The dependences of this LTE-non-LTE difference on rate coefficients, thermal structure, surface pressure, and solar zenith angle (SZA) are studied. In contrast to the large effect of the SZA on the solar heating rate, we find it is not important for the LTE-non-LTE relative difference, which permits a simple tabulation of the non-LTE effect as a function of pressure only. A table of LTE correction factors for the solar heating rate is included for its potential use as a fast yet accurate operative scheme within GCMs.
M Lopezpuertas - One of the best experts on this subject based on the ideXlab platform.
-
radiation transfer in the atmosphere non Local Thermodynamic Equilibrium
Reference Module in Earth Systems and Environmental Sciences#R##N#Encyclopedia of Atmospheric Sciences (Second Edition), 2015Co-Authors: M Lopezpuertas, B FunkeAbstract:This article introduces the concept of non-Local Thermodynamic Equilibrium (non-LTE) in planetary atmospheres and provides a basic theoretical framework of non-LTE radiative transfer and statistical Equilibrium of molecular states. Accurate and approximate solutions of the non-LTE problem are discussed. A climatology of non-LTE populations of the most important vibrational levels of the atmospheric species is provided. Examples of non-LTE applications in general circulation models and the remote sensing of the Earth's and other planetary atmospheres are given.
-
evidence for n2o ν3 4 5 μm non Local Thermodynamic Equilibrium emission in the atmosphere
Geophysical Research Letters, 2007Co-Authors: M Lopezpuertas, T. Von Clarmann, B Funke, Udo Grabowski, G. P. Stiller, D Bermejopantaleon, M HopfnerAbstract:[1] We present a clear evidence for N2O 4.5 μm non-Local Thermodynamic Equilibrium (non-LTE) emissions in the daylight stratosphere and mesosphere from measurements by the MIPAS experiment on board Envisat. We have used non-LTE radiative transfer models in order to quantify the magnitude and extent of the non-LTE deviation of N2O(001) in the Earth's atmosphere. The departure from LTE in N2O during daytime commences at altitudes around 40–50 km, but have significant effects (10%) on daytime limb radiance down to tangent heights of 20 km. The enhancement increases rapidly with altitude, being 20–80% at 50 km, and reaching factors of 2–8 in the lower mesosphere. This study shows that the enhancement is mainly produced by absorption of solar radiation by N2O at 4.5 μm and by V-V collisions with N2(1). Non-LTE effects are also significant at nighttime, where LTE calculations overpredict N2O radiances by 10–20% at 40–55 km tangent heights.
-
evidence for ch4 7 6 μm non Local Thermodynamic Equilibrium emission in the mesosphere
Geophysical Research Letters, 2005Co-Authors: M Lopezpuertas, T. Von Clarmann, B Funke, Maria-elissavet Koukouli, Norbert Glatthor, Udo Grabowski, Sergio Gillopez, G. P. StillerAbstract:[1] We present unequivocal evidence for CH4 7.6 μm non-Local Thermodynamic Equilibrium (non-LTE) mesospheric emissions as measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ESA Envisat satellite. We have employed non-LTE radiative transfer models, already used and validated in studies of other atmospheric gases, in order to quantify the magnitude and extent of the CH4 non-LTE deviation in the Earth's atmosphere. The observed daytime enhancement signatures apparent in the measured radiances cannot be attributed to enhanced daytime temperatures and/or CH4 abundance variations and are reproduced successfully with a dedicated CH4 non-LTE radiative transfer model. We conclude that, depending on the upper stratospheric/mesospheric temperature structure, the departure from LTE might commence at an altitude as low as 45 km, reaching limb radiance deviations of 20% at 60 km and quickly rising up to 60% at 70 km, for the 7.6 μm CH4 lines.
-
non Local Thermodynamic Equilibrium in general circulation models of the martian atmosphere 1 effects of the Local Thermodynamic Equilibrium approximation on thermal cooling and solar heating
Journal of Geophysical Research, 1998Co-Authors: M A Lopezvalverde, M Lopezpuertas, D P Edwards, Cristina RoldánAbstract:Calculations of CO2 thermal cooling and near-IR solar heating rates under non-Local Thermodynamic Equilibrium (non-LTE) situations have been performed to understand and evaluate the effects of non-LTE on the energy balance of the upper atmosphere of Mars. We find that the 15-μm cooling rates can be in error if LTE is assumed above 80 km. In general, the correct non-LTE values are significantly smaller than the LTE values above about 85 km, but the magnitude and sign of the error depend on the temperature structure and the top altitude of the model and, to a lesser extent, on the collisions with atomic oxygen. A detailed analysis of the relevance of the upper boundary layer and a suggested buffer region are presented for both LTE and non-LTE. Based on general considerations of the thermal profile in the mesosphere and lower thermosphere, recommendations for general circulation models (GCM) are presented as a first guide for minimizing the LTE cooling rates inaccuracies. The error of assuming LTE on the CO2 near-IR solar heating rates is found to be about 20% at 85 km and increases strongly above this altitude. The dependences of this LTE-non-LTE difference on rate coefficients, thermal structure, surface pressure, and solar zenith angle (SZA) are studied. In contrast to the large effect of the SZA on the solar heating rate, we find it is not important for the LTE-non-LTE relative difference, which permits a simple tabulation of the non-LTE effect as a function of pressure only. A table of LTE correction factors for the solar heating rate is included for its potential use as a fast yet accurate operative scheme within GCMs.
-
non Local Thermodynamic Equilibrium lte atmospheric limb emission at 4 6 μm 1 an update of the co2 non lte radiative transfer model
Journal of Geophysical Research, 1998Co-Authors: M Lopezpuertas, Guillermo Zaragoza, M A Lopezvalverde, F W TaylorAbstract:An update of the CO2 non Local Thermodynamic Equilibrium (LTE) radiative transfer model of Lopez-Puertas et al. [1986a,b] is presented. The major improvements are (1) a revision of the modified Curtis matrix method; (2) a significant extension of the CO2 vibrational levels and bands (the current version includes 76 states and 129 transitions); and (3) a revision of the excitation mechanisms and collisional parameters. The major differences with previous results are discussed.
T. Von Clarmann - One of the best experts on this subject based on the ideXlab platform.
-
Evidence for N2O ν3 4.5 μm non‐Local Thermodynamic Equilibrium emission in the atmosphere
Geophysical Research Letters, 2007Co-Authors: Manuel López-puertas, T. Von Clarmann, Bernd Funke, Udo Grabowski, G. P. Stiller, D. Bermejo-pantaleón, Michael HöpfnerAbstract:[1] We present a clear evidence for N2O 4.5 μm non-Local Thermodynamic Equilibrium (non-LTE) emissions in the daylight stratosphere and mesosphere from measurements by the MIPAS experiment on board Envisat. We have used non-LTE radiative transfer models in order to quantify the magnitude and extent of the non-LTE deviation of N2O(001) in the Earth's atmosphere. The departure from LTE in N2O during daytime commences at altitudes around 40–50 km, but have significant effects (10%) on daytime limb radiance down to tangent heights of 20 km. The enhancement increases rapidly with altitude, being 20–80% at 50 km, and reaching factors of 2–8 in the lower mesosphere. This study shows that the enhancement is mainly produced by absorption of solar radiation by N2O at 4.5 μm and by V-V collisions with N2(1). Non-LTE effects are also significant at nighttime, where LTE calculations overpredict N2O radiances by 10–20% at 40–55 km tangent heights.
-
evidence for n2o ν3 4 5 μm non Local Thermodynamic Equilibrium emission in the atmosphere
Geophysical Research Letters, 2007Co-Authors: M Lopezpuertas, T. Von Clarmann, B Funke, Udo Grabowski, G. P. Stiller, D Bermejopantaleon, M HopfnerAbstract:[1] We present a clear evidence for N2O 4.5 μm non-Local Thermodynamic Equilibrium (non-LTE) emissions in the daylight stratosphere and mesosphere from measurements by the MIPAS experiment on board Envisat. We have used non-LTE radiative transfer models in order to quantify the magnitude and extent of the non-LTE deviation of N2O(001) in the Earth's atmosphere. The departure from LTE in N2O during daytime commences at altitudes around 40–50 km, but have significant effects (10%) on daytime limb radiance down to tangent heights of 20 km. The enhancement increases rapidly with altitude, being 20–80% at 50 km, and reaching factors of 2–8 in the lower mesosphere. This study shows that the enhancement is mainly produced by absorption of solar radiation by N2O at 4.5 μm and by V-V collisions with N2(1). Non-LTE effects are also significant at nighttime, where LTE calculations overpredict N2O radiances by 10–20% at 40–55 km tangent heights.
-
Evidence for CH4 7.6 μm non‐Local Thermodynamic Equilibrium emission in the mesosphere
Geophysical Research Letters, 2005Co-Authors: Manuel López-puertas, T. Von Clarmann, Bernd Funke, Maria-elissavet Koukouli, Sergio Gil-lopez, Norbert Glatthor, Udo Grabowski, G. P. StillerAbstract:[1] We present unequivocal evidence for CH4 7.6 μm non-Local Thermodynamic Equilibrium (non-LTE) mesospheric emissions as measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ESA Envisat satellite. We have employed non-LTE radiative transfer models, already used and validated in studies of other atmospheric gases, in order to quantify the magnitude and extent of the CH4 non-LTE deviation in the Earth's atmosphere. The observed daytime enhancement signatures apparent in the measured radiances cannot be attributed to enhanced daytime temperatures and/or CH4 abundance variations and are reproduced successfully with a dedicated CH4 non-LTE radiative transfer model. We conclude that, depending on the upper stratospheric/mesospheric temperature structure, the departure from LTE might commence at an altitude as low as 45 km, reaching limb radiance deviations of 20% at 60 km and quickly rising up to 60% at 70 km, for the 7.6 μm CH4 lines.
-
evidence for ch4 7 6 μm non Local Thermodynamic Equilibrium emission in the mesosphere
Geophysical Research Letters, 2005Co-Authors: M Lopezpuertas, T. Von Clarmann, B Funke, Maria-elissavet Koukouli, Norbert Glatthor, Udo Grabowski, Sergio Gillopez, G. P. StillerAbstract:[1] We present unequivocal evidence for CH4 7.6 μm non-Local Thermodynamic Equilibrium (non-LTE) mesospheric emissions as measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ESA Envisat satellite. We have employed non-LTE radiative transfer models, already used and validated in studies of other atmospheric gases, in order to quantify the magnitude and extent of the CH4 non-LTE deviation in the Earth's atmosphere. The observed daytime enhancement signatures apparent in the measured radiances cannot be attributed to enhanced daytime temperatures and/or CH4 abundance variations and are reproduced successfully with a dedicated CH4 non-LTE radiative transfer model. We conclude that, depending on the upper stratospheric/mesospheric temperature structure, the departure from LTE might commence at an altitude as low as 45 km, reaching limb radiance deviations of 20% at 60 km and quickly rising up to 60% at 70 km, for the 7.6 μm CH4 lines.
-
Intercomparison of radiative transfer codes under non-Local Thermodynamic Equilibrium conditions
Journal of Geophysical Research, 2002Co-Authors: T. Von Clarmann, Anu Dudhia, David P. Edwards, Bernd Funke, Michael Höpfner, Brian Kerridge, V. S. Kostsov, Andrea Linden, Manuel López-puertas, Yu. M. TimofeyevAbstract:[1] Limb infrared spectra calculated by the Optimized and Precise Radiative Transfer Algorithm (KOPRA), GENLN2, Reference Forward Model (RFM), and Simulation Program for Infrared Radiative Transfer (SPIRT) radiative transfer algorithms were intercompared for both Local Thermodynamic Equilibrium (LTE) and non-Local Thermodynamic Equilibrium (non-LTE) conditions, in the latter case for given profiles of vibrational temperatures. The overall agreement is usually better than approximately 0.5%, except for isolated phenomena that have been assessed in more detail. Most spectral radiance discrepancies occur also under LTE conditions and are attributed to different treatment of far wings of lines, integration schemes, and mass-weighted averaging of atmospheric temperature and pressure along slant path segments as well as different spectral sampling during the calculation of monochromatic radiances.
G. Faussurier - One of the best experts on this subject based on the ideXlab platform.
-
Model uncertainties of Local-Thermodynamic-Equilibrium K-shell spectroscopy
High Energy Density Physics, 2016Co-Authors: Taisuke Nagayama, C. Blancard, Stephanie B. Hansen, James E. Bailey, Roberto Mancini, Carlos A. Iglesias, H.-k. Chung, James Colgan, Ph. Cosse, G. FaussurierAbstract:Abstract Local-Thermodynamic-Equilibrium (LTE) K-shell spectroscopy is a common tool to diagnose electron density, ne, and electron temperature, Te, of high-energy-density (HED) plasmas. Knowing the accuracy of such diagnostics is important to provide quantitative conclusions of many HED-plasma research efforts. For example, Fe opacities were recently measured at multiple conditions at the Sandia National Laboratories Z machine (Bailey et al., 2015), showing significant disagreement with modeled opacities. Since the plasma conditions were measured using K-shell spectroscopy of tracer Mg (Nagayama et al., 2014), one concern is the accuracy of the inferred Fe conditions. In this article, we investigate the K-shell spectroscopy model uncertainties by analyzing the Mg spectra computed with 11 different models at the same conditions. We find that the inferred conditions differ by ±20–30% in ne and ±2–4% in Te depending on the choice of spectral model. Also, we find that half of the Te uncertainty comes from ne uncertainty. To refine the accuracy of the K-shell spectroscopy, it is important to scrutinize and experimentally validate line-shape theory. We investigate the impact of the inferred ne and Te model uncertainty on the Fe opacity measurements. Its impact is small and does not explain the reported discrepancies.
-
Non-Local Thermodynamic Equilibrium response matrix
Journal of Quantitative Spectroscopy & Radiative Transfer, 2002Co-Authors: G. Faussurier, Richard M. MoreAbstract:Abstract A connection between atomic kinetics and non-Equilibrium Thermodynamics has been recently established using a collisional-radiative model modified to include line absorption. The net emission can be expressed as a symmetric non-Local Thermodynamic-Equilibrium response-matrix. This connection is extended to models used in hydrodynamic codes to simulate laser–plasma interactions. A new, exact and, general formula is obtained for the response-matrix and an analytic proof is given, that is symmetric in the context of collisional-radiative rate equations. To go beyond the near-LTE response-matrix, a response-tensor can be considered that generalizes the response matrix.
-
STATISTICAL MECHANICS OF AVERAGE IONS IN NON-Local Thermodynamic Equilibrium PLASMAS
Journal of Quantitative Spectroscopy and Radiative Transfer, 1998Co-Authors: Alessandro Mirone, Franck Gilleron, J. C. Gauthier, G. FaussurierAbstract:In the framework of the average-atom model, a statistical method has been de- veloped to calculate the temporal evolution of two-electron correlations of highly charged ion plasmas in non-Local Thermodynamic Equilibrium conditions. The new formalism is fast enough to be used in a hydrodynamic code for on-line calculations of configuration populations for the screened-hydrogenic theory. Preliminary numerical results are presented and discussed. ( 1998 Elsevier Science Ltd. All right reserved. 1. I NTRODUCTION
-
Statistical mechanics of highly charged ion plasmas in Local Thermodynamic Equilibrium
Physical Review E, 1997Co-Authors: G. Faussurier, C. Blancard, A. DecosterAbstract:The screened-hydrogenic average-atom model is well suited to describe multicharged ion plasmas in Local Thermodynamic Equilibrium (LTE) for in-line plasma physics calculations. Using general principles of statistical mechanics, this model is shown to be properly defined and Thermodynamically consistent. The grand canonical partition function ${Z}_{G}$ of the bound electrons is written as a multidimensional integral. Its saddle-point evaluation gives the intuitive average-atom equations. Using this formalism, a method for accounting the various ionization stages of a LTE plasma is proposed. It can be used to estimate the integer charge stage distribution in this type of medium from any average-atom model. Once the model is well established, simpler formulas, more suitable for fast computations, are derived in the framework of the classical theory of fluctuations. Numerical results are presented and discussed.
Miguel Lopez-valverde - One of the best experts on this subject based on the ideXlab platform.
-
Non‐Local Thermodynamic Equilibrium in general circulation models of the Martian atmosphere 1. Effects of the Local Thermodynamic Equilibrium approximation on thermal cooling and solar heating
Journal of Geophysical Research: Planets, 1998Co-Authors: Miguel Lopez-valverde, David P. Edwards, Manuel López-puertas, Cristina RoldánAbstract:Calculations of CO2 thermal cooling and near-IR solar heating rates under non-Local Thermodynamic Equilibrium (non-LTE) situations have been performed to understand and evaluate the effects of non-LTE on the energy balance of the upper atmosphere of Mars. We find that the 15-μm cooling rates can be in error if LTE is assumed above 80 km. In general, the correct non-LTE values are significantly smaller than the LTE values above about 85 km, but the magnitude and sign of the error depend on the temperature structure and the top altitude of the model and, to a lesser extent, on the collisions with atomic oxygen. A detailed analysis of the relevance of the upper boundary layer and a suggested buffer region are presented for both LTE and non-LTE. Based on general considerations of the thermal profile in the mesosphere and lower thermosphere, recommendations for general circulation models (GCM) are presented as a first guide for minimizing the LTE cooling rates inaccuracies. The error of assuming LTE on the CO2 near-IR solar heating rates is found to be about 20% at 85 km and increases strongly above this altitude. The dependences of this LTE-non-LTE difference on rate coefficients, thermal structure, surface pressure, and solar zenith angle (SZA) are studied. In contrast to the large effect of the SZA on the solar heating rate, we find it is not important for the LTE-non-LTE relative difference, which permits a simple tabulation of the non-LTE effect as a function of pressure only. A table of LTE correction factors for the solar heating rate is included for its potential use as a fast yet accurate operative scheme within GCMs.
-
Non Local Thermodynamic Equilibrium (LTE) atmospheric limb emission at 4.6 μm: 1. An update of the CO2 non‐LTE radiative transfer model
Journal of Geophysical Research: Atmospheres, 1998Co-Authors: Manuel López-puertas, Miguel Lopez-valverde, Guillermo Zaragoza, Fredric W. TaylorAbstract:An update of the CO2 non Local Thermodynamic Equilibrium (LTE) radiative transfer model of Lopez-Puertas et al. [1986a,b] is presented. The major improvements are (1) a revision of the modified Curtis matrix method; (2) a significant extension of the CO2 vibrational levels and bands (the current version includes 76 states and 129 transitions); and (3) a revision of the excitation mechanisms and collisional parameters. The major differences with previous results are discussed.
-
Non-Local Thermodynamic Equilibrium limb radiances for the mipas instrument on Envisat-1
Journal of Quantitative Spectroscopy and Radiative Transfer, 1998Co-Authors: Manuel López-puertas, T. Von Clarmann, Miguel Lopez-valverde, Guillermo Zaragoza, F. J. Martín-torres, G. M. Shved, Rada Manuilova, A. A. Kutepov, O. Gusev, Andrea LindenAbstract:Abstract An evaluation of the effects that the assumption of Local Thermodynamic Equilibrium (LTE) has on the retrieval of pressure, temperature and the five primary target gases (O 3 , H 2 O, CH 4 , N 2 O, and HNO 3 ) from spectra to be taken by Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the Envisat-1 platform has been conducted. For doing so, non-LTE and LTE limb radiances in the spectral range of 680–2275 cm −1 (4.15–14.6 μm) with a resolution of 0.05 cm −1 at tangent heights from 10 to 70 km have been computed. These calculations included the most updated non-LTE populations of a large number of vibrational levels of the CO 2 , O 3 , H 2 O, CH 4 , N 2 O and HNO 3 molecules which cause the most prominent atmospheric infrared emissions. A discussion of the most important non-LTE effects on the limb radiances as well as on the retrievals of pressure-temperature and volume mixing ratios of O 3 , H 2 O, CH 4 , N 2 O, and HNO 3 is presented, together with the most important non-LTE issues that could be studied with the future coming of MIPAS data.
-
Local Thermodynamic Equilibrium of carbon dioxide in the upper atmosphere
Geophysical Research Letters, 1992Co-Authors: Clive D. Rodgers, Manuel López-puertas, Fredric W. Taylor, Ann Muggeridge, Miguel Lopez-valverdeAbstract:The rotational and vibrational temperatures of the v2 and 2v2 modes of carbon dioxide in the upper atmosphere have been derived from transmission spectra measured by the ATMOS instrument on Spacelab 3 over the height range 60–110 km. The rotational and vibrational temperature profiles are found to be nearly identical, which leads to the conclusion that the CO2 (v2) level is in Local Thermodynamic Equilibrium (LTE) within the experimental errors up to 95 km, and very nearly so to at least 110 km. The CO2 (2v2) level is found to be close to LTE up to at least the upper height limit of its retrieval, i.e., 93 km. The interpretation of those measurements using a non-LTE model [Lopez-Puertas et al., 1986] supports a fast rate for the deactivation of CO2(v2) by atomic oxygen, similar to that derived by Sharma and Wintersteiner [1990]. This provides independent confirmation, from a qualitatively different type of measurement, of the conclusion of those authors that the radiative cooling of the upper atmospheres of the Earth is around an order of magnitude greater than our 1986 model predicted. It also has implications for thermospheric cooling on the other terrestrial planets, as well as expanding the possibilities for future remote sensing of the temperature of the upper mesosphere and lower thermosphere, since the upper limit which can be sounded is higher than previously believed.
