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Solar wind-driven geopotential height anomalies originate in the Antarctic lower troposphere
Past researchers have found that variations in the interplanetary magnetic field – the magnetic field swept Earthwards by the solar wind – are correlated with effects in the Earth’s troposphere. These effects are therefore correlated, both geographically and temporally, with changes to the ionospheric electric potential and to the planet-wide current system known as the global atmospheric electric circuit. The precise details of the mechanism that causes the changes to atmospheric dynamics remain relatively unknown.
In a recent paper in Geophysical Research Letters, Lam et al. examine the Mansurov effect, which is the day-to-day correlation between changes in the interplanetary magnetic field and atmospheric pressure anomalies at the polar surface. They were specifically looking for evidence of the Mansurov effect above the Earth’s surface to see if its signature there could shed light on the mechanism. Using four years of reanalysis data, the authors did indeed see a pressure response in the troposphere over Antarctica to changes in the interplanetary magnetic field. The response was very highly statistically-significant within the troposphere but not so in the stratosphere, and was seen in the lower troposphere days sooner than in the mid-to-upper troposphere. The signature of the Mansurov effect is therefore consistent with the upward propagation of solar wind-induced change in the lower troposphere, and is in sharp contrast to the much slower downward propagation – from stratosphere to troposphere – of effects due to solar changes involving ultraviolet radiation or energetic particle precipitation. The paper shows that there are solar-driven changes in the troposphere that possibly involve the action of the global atmospheric electric circuit on lower tropospheric clouds.
Link to the full paper in the NERC Open Research Archive
Authors
Mai Mai Lam, Gareth Chisham, Mervyn P. Freeman
Publication
Geophysical Research Letters, 10.1002/2014GL061421
