On the force of vertical winds in the upper atmosphere -- consequences for small biological particles

TL;DR

This paper investigates how vertical winds in the upper atmosphere can transport tiny biological particles to higher altitudes than previously observed, with implications for astrobiology and climate science.

Contribution

It introduces a simple model estimating particle altitude climbs due to vertical winds, suggesting particles can reach higher altitudes than known, impacting astrobiology and climate studies.

Findings

Particles can reach altitudes above 120 km due to vertical winds.

Vertical wind observations are challenging, but they could enable higher particle transport.

Implications for astrobiology include potential pathways for biological material in space.

Abstract

For many decades vertical winds have been observed at high altitudes of the Earth's atmosphere, in the mesosphere and thermosphere layers. These observations have been used with a simple one dimensional model to make estimates of possible altitude climbs by biologically sized particles deeper into the thermosphere, in the rare occurrence where such a particle has been propelled to these altitudes. A particle transport mechanism is suggested from the literature on auroral arcs, indicating that an altitude of 120 km could be reached by a nanometer sized particle which is higher than the measured 77 km limit on the biosphere. Vertical wind observations in the upper mesophere and lower thermosphere are challenging to make and so we suggest that particles could reach altitudes greater than 120 km, depending on the magnitude of the vertical wind. Applications of the larger vertical winds in the upper atmosphere to astrobiology and climate science are explored.