The thermosphere at South Pole

• Main Authors: Smith, Roger W., Hernandez, Gonzalo
• Format: Report
• Language: English
• Published: University of Alaska Fairbanks, Geophysical Institute/Graduate Program in Geophysics, AK-50, University of Washington 1998
• Subjects: South Pole; Memoirs of National Institute of Polar Research; Polar Research; South pole
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2312; http://id.nii.ac.jp/1291/00002312/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2312&item_no=1&attribute_id=18&file_no=1

The Earth's thermosphere provides the first layer of atmosphere to filter the sun's optical radiation on its way to the surface. In addition, it absorbs most of the energetic particles swept up from interplanetary space and guided downwards along magnetic field lines. The most variable components of these sources of incoming energy are the energetic particles associated with the aurora and the extreme ultraviolet radiation dependent on solar activity. Because of this defensive role, the thermosphere is the place where incoming radiations are converted to heat. At high latitudes, such as South Pole, the thermospheric temperature is strongly dependent on solar and geomagnetic activity. Energetic photons and charged particles ionize the thermosphere, creating the ionosphere. Currents of millions of amps flow in the high latitude ionosphere causing additional heating and associated dynamical forcing through ion drag on the neutral gas particles. Winds driven by this drag are a persistent feature of the high latitude thermosphere. The electric fields which drive them originate the solar-terrestrial dynamo and are subject to reversals dependent on the sign of the interplanetary magnetic field component in the plane of the solar ecliptic. Hence the winds and temperatures in the thermosphere depend strongly on interplanetary phenomena.