BAS Geospace Atmosphere Transfer Functions

Lead Research Organisation: NERC British Antarctic Survey

Abstract

Although the Earth's lower atmosphere is warming, the upper atmosphere will be cooled by increasing levels of greenhouse gases. The greatest cooling may occur in the least explored region of our atmosphere, below the level of orbiting satellites and above the highest balloons, known as the mesosphere and lower thermosphere (60-180 km altitude). This region connects geospace – where the atmospheres of the Sun and Earth converge – to the lower atmosphere. This is a complex region of opposites where great surges of energy meet, carried downward by particles energised by the solar wind which create dramatic auroral displays, and upward from the troposphere and stratosphere by atmospheric tides and waves – creating the Earth's coldest environment (-145°C) at 85 km altitude in the mesopause. In this program, BAS scientists aimed to exploit the unique conditions in the Antarctic upper atmosphere to improve our understanding of global upper atmospheric circulation, temperature balance, short-term variability, long-term changes, and how these changes may be linked to human activity. Objectives were: a) to study the vertical coupling of energy linking upper and lower atmospheres; b) to identify what controls the extremely cold mesopause temperatures around 85 km; c) to confirm whether long-term change in the upper atmosphere is present and, if so, whether it occurs naturally or is linked to human activity; d) to understand what causes differences between the Antarctic and Arctic in the mesosphere and thermosphere; e) to quantify the balance of energy at 60-150 km altitude from solar, magnetospheric, meteorological and chemical sources; f) to assess the effect of mesosphere and thermosphere energetics and dynamics on people due to our increasing use of space.

Publications

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Diettrich J (2006) Statistics of sporadic iron layers and relation to atmospheric dynamics in Journal of Atmospheric and Solar-Terrestrial Physics

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Hibbins R (2006) Mean winds and tides in the mesosphere and lower thermosphere above Halley, Antarctica in Journal of Atmospheric and Solar-Terrestrial Physics