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Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 01/05 Podcast
Non-LTE diagnostics of the infrared observations of the planetary atmosphere

Non-LTE diagnostics of the infrared observations of the planetary atmosphere

Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 01/05 vor 23 Jahren

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The analysis of the infrared measurements of a number of
sophisticated space experiments requires modeling of molecular
infrared radiation with accounting for the nonlocal thermodynamic
equilibrium (non--LTE). In this dissertation a general formulation
is given of the multilevel vibrational-rotational non-LTE problem
for a mixture of radiating molecular gases in a planetary
atmosphere. The approach for the solution of this problem suggested
here utilizes the Accelerated Lambda Iteration (ALI) technique
developed in stellar astrophysics for spectrum formation
calculations and for the computation of non-LTE model stellar
atmospheres. This new for atmospheric science technique is not
subject to the limitations of the traditional matrix and
conventional lambda iteration methods which dominate the studies
dealing with non-LTE in planetary atmospheres. In the case of the
CO2 non-LTE problems in the atmospheres of Earth and Mars it is
demonstrated that ALI approach is far superior to the other
algorithms in minimizing computer time and storage and in
converging much more rapidly. While ``atmospheric'' groups
concentrated on the development of codes suitable for treatment of
limited number of selected non-LTE problems the computer code
package ALI-ARMS (for ``Accelerated Lambda Iteration for
Atmospheric Radiation and Molecular Spectra'') compiled in
framework of this study allows non-LTE treatment of arbitrary
number of molecules interacting by collisionally induced exchange
of energy and by the band overlaps. It was applied to the analysis
of large amount of the infrared limb radiance data obtained both in
the CRyogenic Infrared Spectrometers and Telescopes for the
Atmosphere (CRISTA) experiments on board of the german ASTRO-SPAS
satellite and by the Thermal Emission Spectrometer (TES) instrument
orbiting Mars on board of the NASA Mars Global Surveyor (MGS)
satellite. In case of the Earth's atmosphere first detailed
distributions of temperature and trace gas concentrations in the
upper mesosphere and lower thermosphere were obtained. The
retrieved temperature data confirmed the ``two-level'' structure of
the Earth's mesopause which was recently discovered in the lidar
and rocket experiments. These results contribute to the studies of
the mesosphere, which is considered today to be the tracer of the
global climate changes.