Mesospheric Dust

Project funded by Research Council of Norway (grant 275503)

Cosmic dust and meteoroids and their fragments play an important role in the physical and chemical processes of the upper atmosphere. Cosmic dust and meteoroids impact the atmosphere at high speeds and ablate at ~ 75 to ~110 km. As a result, atoms and atomics ions of the metallic elements Fe, Mg, Si and Na, oxides, hydroxides and carbonates exist and form nm-sized meteoric smoke particles (MSPs). These dust particles probably act as nuclei for condensation of water ice and affect the charge balance in the upper mesosphere. The atmospheric circulation system in the Polar Regions in summer causes adiabatic cooling in the mesosphere so that the temperature can be ~120 K or lower so that ice particles form on the MSPs. During summer the dust particles form a core for the condensation of ice particles that lead to the formation of Noctilucent Clouds (NLC) and Polar Mesospheric Summer Echoes (PMSE). The distribution of the solid particles that is governed by neutral atmospheric dynamics provides a coupling between the atmospheric layers.Size and charge of dust particles are important parameters because they influence determine growth rates, chemical processes and PMSE formation. Through interacting with the ionospheric electrons and ions the charged dust also influences the incoherent scatter process observed with radar. We propose to study the dust in the ionosphere using model calculations, in-situ measurements and radar observations in order determine the smallest dust size in the ionosphere and dust charging rates. We revisit and consider results from rocket observations, use them as a basis of our studies and develop a set of measurement questions for the sample return of mesospheric dust particles and we develop a study programme to use the future EISCAT_3D to study mesospheric dust. 

The primary objective of this project is to reveal the sizes, size distribution, composition and charging rates of mesospheric dust particles and to formulate measurement questions to future sample return observations. The secondary objective it to study the influence of charged dust on PMSE formation and incoherent scatter spectra and to define a programme of future incoherent scatter observations.

Responsible: Ingrid Mann