Joule heating effects on ionosphere-thermosphere coupling and neutral density (JOIN)

JOIN

During geomagnetic storms intense Joule heating causes thermal expansion of the upper atmosphere, thus increasing satellite drag at low Earth orbits (LEO). In the JOIN project we determine the statistical distribution of the auroral Joule heating in the northern hemisphere during geomagnetic storms, and compared it with atmospheric density variations observed by the Swarm, and GRACE satellites.

Funders

ESA

Project information

Project duration

-

Funded by

Other International

Project funder

European Space Agency

Project coordinator

University of Oulu

Unit and faculty

Space Physics and Astronomy
Faculty of Science

Project description

During geomagnetic storms large amounts of energy originating from the solar wind is deposited in the auroral ionosphere as Joule heating at 100-150 km altitudes. This causes the tenuous upper atmosphere to heat up and expand, which results in increased atmospheric drag experienced by satellites at low-Earth obits (LEO). In this project we create new tools for estimating the amount of Joule heating in the northern auroral regions, and carry out a detailed investigation of its consequences on the neutral atmosphere at satellite altitudes.

An important aspect of the work is to distinguish between different types of solar wind structures that drive geomagnetic storms, namely solar wind high speed streams (HSS) or interplanetary coronal mass ejections (ICME), and to investigate possible differences in the atmospheric responses to these drivers. The work is divided into four work packages:

  1. Determine the global statistical distribution and variability of the high-latitude Joule heating during geomagnetic storms driven by HSSs or ICMEs.
  2. Correlate the storm-time Joule heating with observed large-scale atmospheric density variations at low Earth orbits (LEO).
  3. Estimate variations in the atmospheric scale height by directly comparing density measurements from two different altitudes during co-planarity periods between various LEO satellites at polar orbits.
  4. Perform event studies of meso-scale Joule heating and density variations at auroral regions by utilizing conjunctions between Swarm satellites and incoherent scatter radars (e.g., EISCAT and Poker flat).

See also the project website at ESA's Science for Society site.

Project personnel
+ Dr Heikki Vanhamäki (project leader)
+ Professor Anita Aikio
+ Dr Ilkka Virtanen
+ Dr Lei Cai
+ Dr Marcus Pedersen
+ MSc Milla Myllymaa

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Project results

Reports and other project results will be collected in this folder as they become available. These include:
+ Project Science case from the pre-KO meeting.
+ Pedersen et al. poster at ESWW 2024.
+ Vanhamäki et al. talk at 14th Swarm Data Quality Workshop 2024.
+ Cai et al. poster at EGU 2025.
+ Pedersen et al. talk at EGU 2025.
+ Vanhamäki et al. talk at LPS 2025.

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For the general public
Article Swarm in tune with atmospheric hot flushes by ESA.

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Manuscripts and published articles
Cai L., A.T. Aikio, G.P. Geethakumari, H. Vanhamäki, I.I. Virtanen, S. Oyama, Y. Zhang, J. Zhang, and M.R. Hairston: ``Ionosphere-Thermosphere Coupling in the Northern Polar Region during the May 2024 Geomagnetic Superstorm''. Manuscript submitted to Journal of Geophysical Research, 2025.

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Presentations at conferences
Iorfida E., L. Küchelbacher, S. Wüst , W. Miloch, H. Vanhamäki, A. Dimmock, C. Finlay, I. Daras, R. Sabia, A. Strømme, L. Trenchi, M.G.G.T. Taylor, D. Prieto: "ESA Swarm 4D Ionosphere: outline of the five contributing studies". Swarm 10 Years Anniversary & Science Conference, poster presentation, Copenhagen, 8-12 April 2024.

Iorfida E., C. Schmidt, W. Miloch, E. Doornbos, A. Aikio, S. Buchert, C. Finlay, A. Strømme, and D.F. Prieto: ``4D Ionosphere – where we stand and where we are going''. Living Planet Symposium, panel discussion, Vienna, 23-27 June 2025.

Pedersen M., H. Vanhamäki, A. Aikio, L. Cai, and M. Myllymaa: ``Joule heating effects on ionosphere-thermosphere coupling and neutral density (JOIN) project: preliminary results''. European Space Weather Week, poster presentation, Coimbra, 4–8 November 2024.

Pedersen, M., H. Vanhamäki, A. Aikio, L. Cai, M. Myllymaa, C. Waters, and J. Gjerloev: Joule heating and neutral density enhancements during geomagnetic storms driven by solar wind high-speed streams and coronal mass ejections, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, , https://doi.org/10.5194/egusphere-egu25-16944, 2025.

Vanhamäki H., A. Aikio, L. Cai, M. Pedersen and M. Myllymaa: ``Joule heating effects on ionosphere-thermosphere coupling and neutral density (JOIN) project''. 14th Swarm Data Quality Workshop, Bucharest, 7-11 October 2024.

Vanhamäki, H., L. Cai (presenting author), A. Aikio, M. Pedersen, and M. Myllymaa: Variations of upper thermospheric scale height based on neutral mass density measurements from coplanar low-Earth-orbit satellites, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15392, https://doi.org/10.5194/egusphere-egu25-15392, 2025.

Vanhamäki H., A. Aikio, L. Cai, M. Pedersen and M. Myllymaa: ``Ionospheric Joule heating and neutral density variations at low Earth orbits during geomagnetic storms''. Living Planet Symposium, Vienna, 23-27 June 2025.

Research groups

Ionospheric physics