Cosmic Dust in the Atmospheres of Earth and Mars
Abstract:
Cosmic dust particles are produced in the solar system from the sublimation of comets as they orbit close to the sun, and also from collisions between asteroids. Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with a chemical meteoric ablation model enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; the injection of bio-available phosphorous and organics; and the effects of the surface deposition of micrometeorites and cosmic spherules.
In this seminar I will describe the results of a large study designed to determine the input rate of cosmic dust to the terrestrial atmosphere, using a self-consistent treatment of cosmic dust from the outer solar system to the Earth’s surface. An astronomical model which tracks the evolution of dust from various sources into the inner solar system was combined with a chemical ablation model to determine the rate of injection of metallic vapours into the atmosphere. Constraining these coupled models with observations of IR emission from the Zodiacal Cloud, lidar measurements of the vertical fluxes of Na and Fe in the terrestrial mesosphere, and the rate of accretion of cosmic spherules at the South Pole, indicates that about 30 tonnes of dust enters the Earth’s atmosphere each day. The Leeds Chemical Ablation Model (CABMOD) was tested and developed using a novel Meteoric Ablation Simulator, which measures the evaporation of metals from meteoritic particles that are flash heated to over 2800 K with a time-resolved temperature profile simulating atmospheric entry. More recently, we have used a new instrument to explore the pyrolysis of organic material in meteoritic particles, which may cause cosmic particles to fragment during atmospheric entry and limit the delivery of organics to the planetary surface.
I will then describe how whole atmosphere global chemistry-climate models (e.g. WACCM, Mars PCM) can be used to explore the various impacts in the atmosphere and at the surface referred to above. The Mars PCM - with the chemistry of four metals - will be compared against observations of metallic species by NASA’s MAVEN spacecraft. MAVEN arrived at Mars just in time to observe the effect of a near miss of the planet by the comet Siding Spring, and since then has made continuous measurements of the Mg+ layer centred around 90 km, as well as occasional deep dip measurements between ~130 and 180 km.
Previous MIST online seminars are recorded and available on the MIST YouTube channel .
Links to individual seminars are in the table below.
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Date |
Speaker |
Title (Click for Link to Seminar) |
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05 Sep 2023 |
Andrea Larosa (QMUL) |
The relation between magnetic switchbacks and turbulence in the inner heliosphere |
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01 Aug 2023 |
Sheila Kanani (Royal Astronomical Society) |
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11 Jul 2023 |
Harriet Turner (University of Reading) |
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11 Jul 2023 |
Cameron Patterson (Lancaster University) |
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06 Jun 2023 |
Charlotte Goetz (Northumbria University) |
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02 May 2023 |
Mark Lester (University of Leicester) |
Sounding the Martian Ionosphere: New Insights from Mars Express and other satellites at Mars |
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07 Mar 2023 |
Audrey Schillings (University of Leicester) |
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17 Feb 2023 |
Alexandra Fogg (Dublin Institute for Advanced Studies) |
Investigating the effects of solar wind pressure pulses on the terrestrial magnetosphere |
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01 Nov 2022 |
Ingrid Cnossen (British Antarctic Survey) |
Climate of the upper atmosphere: Long-term change and North-South asymmetries |
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04 Oct 2022 |
Alan Wood (University of Birmingham) |
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06 Sept 2022 |
Andrew Kavanagh (British Antarctic Survey) |
Simultaneous multi-scale measurements of Ion Drift in the Earth's Auroral Ionosphere |
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07 June 2022 |
Maria-Theresia Walach (Lancaster University) |
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03 May 2022 |
Chris Owen (MSSL/UCL) |
Solar Orbiter – Progress to date and prospects going forward. |
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05 April 2022 |
Henrik Melin (University of Leicester) |
Aeronomy of the giant planets from over 30 years of H3+ observations |
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01 February 2022 |
Daniel Whiter (University of Southampton) |
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07 December 2021 |
Adam Masters (Imperial College London) |
A More Viscous-Like Solar Wind Interaction With All the Giant Planets |
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02 November 2021 |
Sandra Chapman (University of Warwick) |
‘Data analytics’ approaches to space weather in space and time |
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05 October 2021 |
Laura Berčič (Mullard Space Science Laboratory, UCL) |
Physical mechanisms related to the sunward electron deficit in the solar wind |
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07 September 2021 |
Beatriz Sánchez-Cano (University of Leicester) |
Mars’ Space Weather: the role of the ionosphere for (near) unmagnetised planets |
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06 July 2021 |
Graziella Branduardi-Raymont (University College London) |
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01 June 2021 |
Julia Stawarz (Imperial College London) |
Turbulence and Magnetic Reconnection in Space Plasmas: Insights from the Magnetospheric Multiscale Mission |
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04 May 2021 |
Emma E. Woodfield (British Antarctic Survey) |
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13 April 2021 |
David Themens (University of Birmingham) |
Data first, physics later: How user needs have framed the development of E-CHAIM |
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02 March 2021 |
Martin Archer (Imperial College London) |
Researchers and public engagement: What role should I play to make a real difference? |
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02 February 2021 |
Luke Barnard (University of Reading) |
Coronal Mass Ejection modelling and prediction with Heliospheric Imagers |
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12 January 2021 |
Gabrielle Provan (University of Leicester) |
Magnetosphere-ionosphere coupling at Saturn and Jupiter in the era of Juno and Cassini |
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01 December 2020 |
Mike Lockwood (University of Reading) |
Semi-annual and Universal Time variations in the magnetosphere |
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03 November 2020 |
Clare Watt (Northumbria University) |
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06 October 2020 |
Imogen Gingell (University of Southampton) |
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01 September 2020 |
Caitriona Jackman (Dublin Institute for Advanced Studies) |
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04 August 2020 |
Jim Wild (Lancaster University) |
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14 July 2020 |
Daniel Verscharen (Mullard Space Science Laboratory, UCL) |
Kinetic physics, collisions, and turbulence in the solar wind: a multi-scale perspective |