Zeeman effect in atmospheric O2 measured by ground-based microwave radiometry

[摘要] In this work we study the Zeeman effect on stratospheric O₂ usingground-based microwave radiometer measurements. The interaction of the Earthmagnetic field with the oxygen dipole leads to a splitting of O₂ energystates, which polarizes the emission spectra. A special campaign was carriedout in order to measure this effect in the oxygen emission line centered at53.07 GHz. Both a fixed and a rotating mirror were incorporated into theTEMPERA (TEMPERature RAdiometer)in order to be able to measureunder different observational angles. This new configuration allowed us tochange the angle between the observational path and the Earth magnetic fielddirection. Moreover, a high-resolution spectrometer (1 kHz) was used in orderto measure for the first time the polarization state of the radiation due tothe Zeeman effect in the main isotopologue of oxygen from ground-basedmicrowave measurements. The measured spectra showed a clear polarizedsignature when the observational angles were changed, evidencing the Zeemaneffect in the oxygen molecule. In addition, simulations carried out with theAtmospheric Radiative Transfer Simulator (ARTS) allowed us to verify themicrowave measurements showing a very good agreement between model andmeasurements. The results suggest some interesting new aspects for researchof the upper atmosphere.

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