View in EDS

Power Density Dissipated by Field‐Aligned Currents in the Topside Ionosphere Derived From Swarm‐A Observations.

Saved in:
Bibliographic Details
Title: Power Density Dissipated by Field‐Aligned Currents in the Topside Ionosphere Derived From Swarm‐A Observations.
Authors: Giannattasio, F.1 (AUTHOR) fabio.giannattasio@ingv.it, Mestici, S.2 (AUTHOR), Pignalberi, A.1 (AUTHOR), De Michelis, P.1 (AUTHOR), Tozzi, R.1 (AUTHOR), Alberti, T.1 (AUTHOR), Pezzopane, M.1 (AUTHOR), Coco, I.1 (AUTHOR), Consolini, G.3 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Nov2025, Vol. 130 Issue 11, p1-29. 29p.
Subject Terms: *Ionosphere, *Geomagnetism, *Solar activity, Power density, Magnetic coupling, Artificial satellites, Magnetic fields, Energy dissipation
Abstract: Magnetosphere‐ionosphere (MI) coupling is mainly achieved by field‐aligned currents (FACs) that inject energy and momentum into the high‐latitude ionosphere. A fraction of this energy is locally dissipated and converted into kinetic energy of the ionospheric plasma. Dissipation of FACs in the topside ionosphere has not yet been properly investigated because it is assumed to be negligible due to the expected very high electrical conductivity and weak electric fields in the direction parallel to the geomagnetic field. However, previous studies have shown that: (a) parallel electric fields are not null and may be significant under specific conditions; (b) parallel electrical conductivity, though high, is finite; (c) FACs exhibit distinctive dissipation patterns responding to the dynamics of the topside ionosphere. This study presents maps of local power density dissipated by FACs in both hemispheres by taking advantage of 8 years of data from the Swarm A satellite. It investigates the dependence of dissipation on magnetic latitude, magnetic local time, seasons and solar activity at around 450 km of altitude. The findings point out that while FAC dissipation is small compared to that of horizontal currents at 100–110 km of altitude, it is not negligible and exhibits significant spatial and time variations that are a function of sunlit conditions and solar activity. The obtained results are discussed in terms of the relation between electron density and temperature and particle precipitation, pointing out that dissipation is a clear consequence of MI coupling and the response of MI system to forcing of solar origin. Plain Language Summary: Field‐aligned currents (FACs) are electric currents that flow along Earth's magnetic field lines, linking the outer magnetic environment (magnetosphere) to the high‐latitude upper atmosphere (ionosphere). These currents deliver energy to the ionosphere, where it is partly turned into the movement of surrounding charged particles. Previous research has shown that the ability of the ionosphere to conduct electricity, although high, is not unlimited. This means that FACs can lose energy as they flow. In this study, we performed the first‐ever global maps (covering both Earth's hemispheres) that show where and how FACs lose energy in the upper ionosphere. We used 8 years of data collected every second by the European Space Agency's Swarm A satellite, which orbits about 450 km above the Earth's surface. Our findings reveal that the way FACs lose energy depends on factors like magnetic latitude, local time, seasons, and solar activity. Interestingly, the patterns of energy loss are slightly different in the Northern and Southern hemispheres, highlighting how Earth's upper atmosphere responds differently in each hemisphere to solar influences. Key Points: We analyze 8 years of Swarm A satellite data to study dissipation of field‐aligned currents in the topside ionospherePower density dissipated by field‐aligned currents varies with hemisphere, season, solar illumination, and solar activityA 90° hemispheric tilt and a six‐cell current system in the Northern hemisphere are consistently observed in all cases [ABSTRACT FROM AUTHOR]
Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: GreenFILE
FullText Text:
  Availability: 0
Header DbId: 8gh
DbLabel: GreenFILE
An: 189524680
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
IllustrationInfo
Items – Name: Title
  Label: Title
  Group: Ti
  Data: Power Density Dissipated by Field‐Aligned Currents in the Topside Ionosphere Derived From Swarm‐A Observations.
– Name: Author
  Label: Authors
  Group: Au
  Data: <searchLink fieldCode="AR" term="%22Giannattasio%2C+F%2E%22">Giannattasio, F.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> fabio.giannattasio@ingv.it</i><br /><searchLink fieldCode="AR" term="%22Mestici%2C+S%2E%22">Mestici, S.</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Pignalberi%2C+A%2E%22">Pignalberi, A.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22De+Michelis%2C+P%2E%22">De Michelis, P.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Tozzi%2C+R%2E%22">Tozzi, R.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Alberti%2C+T%2E%22">Alberti, T.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Pezzopane%2C+M%2E%22">Pezzopane, M.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Coco%2C+I%2E%22">Coco, I.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Consolini%2C+G%2E%22">Consolini, G.</searchLink><relatesTo>3</relatesTo> (AUTHOR)
– Name: TitleSource
  Label: Source
  Group: Src
  Data: <searchLink fieldCode="JN" term="%22Journal+of+Geophysical+Research%2E+Space+Physics%22">Journal of Geophysical Research. Space Physics</searchLink>. Nov2025, Vol. 130 Issue 11, p1-29. 29p.
– Name: Subject
  Label: Subject Terms
  Group: Su
  Data: *<searchLink fieldCode="DE" term="%22Ionosphere%22">Ionosphere</searchLink><br />*<searchLink fieldCode="DE" term="%22Geomagnetism%22">Geomagnetism</searchLink><br />*<searchLink fieldCode="DE" term="%22Solar+activity%22">Solar activity</searchLink><br /><searchLink fieldCode="DE" term="%22Power+density%22">Power density</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+coupling%22">Magnetic coupling</searchLink><br /><searchLink fieldCode="DE" term="%22Artificial+satellites%22">Artificial satellites</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+fields%22">Magnetic fields</searchLink><br /><searchLink fieldCode="DE" term="%22Energy+dissipation%22">Energy dissipation</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Magnetosphere‐ionosphere (MI) coupling is mainly achieved by field‐aligned currents (FACs) that inject energy and momentum into the high‐latitude ionosphere. A fraction of this energy is locally dissipated and converted into kinetic energy of the ionospheric plasma. Dissipation of FACs in the topside ionosphere has not yet been properly investigated because it is assumed to be negligible due to the expected very high electrical conductivity and weak electric fields in the direction parallel to the geomagnetic field. However, previous studies have shown that: (a) parallel electric fields are not null and may be significant under specific conditions; (b) parallel electrical conductivity, though high, is finite; (c) FACs exhibit distinctive dissipation patterns responding to the dynamics of the topside ionosphere. This study presents maps of local power density dissipated by FACs in both hemispheres by taking advantage of 8 years of data from the Swarm A satellite. It investigates the dependence of dissipation on magnetic latitude, magnetic local time, seasons and solar activity at around 450 km of altitude. The findings point out that while FAC dissipation is small compared to that of horizontal currents at 100–110 km of altitude, it is not negligible and exhibits significant spatial and time variations that are a function of sunlit conditions and solar activity. The obtained results are discussed in terms of the relation between electron density and temperature and particle precipitation, pointing out that dissipation is a clear consequence of MI coupling and the response of MI system to forcing of solar origin. Plain Language Summary: Field‐aligned currents (FACs) are electric currents that flow along Earth's magnetic field lines, linking the outer magnetic environment (magnetosphere) to the high‐latitude upper atmosphere (ionosphere). These currents deliver energy to the ionosphere, where it is partly turned into the movement of surrounding charged particles. Previous research has shown that the ability of the ionosphere to conduct electricity, although high, is not unlimited. This means that FACs can lose energy as they flow. In this study, we performed the first‐ever global maps (covering both Earth's hemispheres) that show where and how FACs lose energy in the upper ionosphere. We used 8 years of data collected every second by the European Space Agency's Swarm A satellite, which orbits about 450 km above the Earth's surface. Our findings reveal that the way FACs lose energy depends on factors like magnetic latitude, local time, seasons, and solar activity. Interestingly, the patterns of energy loss are slightly different in the Northern and Southern hemispheres, highlighting how Earth's upper atmosphere responds differently in each hemisphere to solar influences. Key Points: We analyze 8 years of Swarm A satellite data to study dissipation of field‐aligned currents in the topside ionospherePower density dissipated by field‐aligned currents varies with hemisphere, season, solar illumination, and solar activityA 90° hemispheric tilt and a six‐cell current system in the Northern hemisphere are consistently observed in all cases [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=8gh&AN=189524680
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1029/2025JA034057
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 29
        StartPage: 1
    Subjects:
      – SubjectFull: Ionosphere
        Type: general
      – SubjectFull: Geomagnetism
        Type: general
      – SubjectFull: Solar activity
        Type: general
      – SubjectFull: Power density
        Type: general
      – SubjectFull: Magnetic coupling
        Type: general
      – SubjectFull: Artificial satellites
        Type: general
      – SubjectFull: Magnetic fields
        Type: general
      – SubjectFull: Energy dissipation
        Type: general
    Titles:
      – TitleFull: Power Density Dissipated by Field‐Aligned Currents in the Topside Ionosphere Derived From Swarm‐A Observations.
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Giannattasio, F.
      – PersonEntity:
          Name:
            NameFull: Mestici, S.
      – PersonEntity:
          Name:
            NameFull: Pignalberi, A.
      – PersonEntity:
          Name:
            NameFull: De Michelis, P.
      – PersonEntity:
          Name:
            NameFull: Tozzi, R.
      – PersonEntity:
          Name:
            NameFull: Alberti, T.
      – PersonEntity:
          Name:
            NameFull: Pezzopane, M.
      – PersonEntity:
          Name:
            NameFull: Coco, I.
      – PersonEntity:
          Name:
            NameFull: Consolini, G.
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 11
              Text: Nov2025
              Type: published
              Y: 2025
          Identifiers:
            – Type: issn-print
              Value: 21699380
          Numbering:
            – Type: volume
              Value: 130
            – Type: issue
              Value: 11
          Titles:
            – TitleFull: Journal of Geophysical Research. Space Physics
              Type: main
ResultId 1