Modeling the Zeeman Effect in Planetary Radiative Transfer and Applications
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Remote sensing is about retrieving distant physical properties from locally observed radiation. The first step to remote sensing is to describe, or model, the radiative transfer. Without locating the origin of the observed radiation, and without proper interpretation of what it represents, understanding and utilizing instrumental results are nearly impossible. The focus of my thesis is on how radiation interacts with a weakly magnetized medium by means of the Zeeman effect. One molecule of particular interest affected by the Zeeman effect is the oxygen molecule. The thesis work started by an implementation of a module for the Zeeman effect in an existingradiative transfer model. Later works has applied this module to Earth and Mars radiative transfer.The high relative concentration of the oxygen molecule in Earth’s atmosphere, and the fact that the molecule interacts with sub-millimeter radiation, has made it a prime target for temperature retrievals using both ground- and satellite-based radiometers. The Zeeman effect is important for molecular oxygen at mesospheric altitudes on Earth, where the geometry of the magnetic field and of the observation influence the polarized absorption of radiation. Simulations of ground-based measurements by a radiometer in Bern, Switzerland, have the Zeeman module reproduce the dependency on observational geometry for the local magnetic field, partly validating the module. Simulations of satellite measurements comparing the Zeeman module to a fast, parameterized, implementation of the Zeeman effect for numerical weather predictions also indicates that the module works. There are small discrepancies between the two models but both are close to the satellite measurements given the noise of these measurements. Work to move beyond simulation space and analyze these satellite measurements to find the atmospheric temperatures at high altitudes also show promising results.Besides Earth applications, the module has been used for Mars conditions, where only trace amounts of molecular oxygen is available. Mars does not have a global magnetic field but instead have several magnetic sources scattered throughout its crust. This gives a magnetic field that is significantly weaker than on Earth and with much more structures. It is possible to utilize the Zeeman effect on molecular oxygen to measure the magnetic field of Mars. The last part of this thesis work suggests a measurement scheme for a satellite capable of retrieving the horizontal components of the Martian crustal magnetic field. It shows the expected errors associated with such a measurement scheme.
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2016.
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Research subject Atmospheric science
IdentifiersURN: urn:nbn:se:ltu:diva-26408Local ID: e214d0f3-26e5-48ef-b0a3-2b3dd7b4057fISBN: 978-91-7583-630-0ISBN: 978-91-7583-631-7 (PDF)OAI: oai:DiVA.org:ltu-26408DiVA: diva2:999570
För godkännande; 2016; 20160422 (ricric); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Richard Larsson Ämne: Rymdteknik/Space Technology Avhandling: Modeling the Zeeman Effect in Planetary Atmospheric Radiative Transfer and Applications Opponent: Dr. Juan R. Pardo, Astrofisika Molecular, Instituto de Ciencia de Materiales de Madrid, Spanish National Research Council, Madrid, Spain. Ordförande: Biträdande professor Mathias Milz, Avdelningen för rymdteknik, Institutionen för system- och rymdteknik, Luleå tekniska universitet, Kiruna. Tid: Torsdag 16 juni kl 09.00 Plats: Aulan, Rymdcampus Kiruna, Luleå tekniska universitet2016-09-302016-09-30