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Fletcher LN, de Pater I, Orton GS, Hofstadter MD, Irwin PGJ, Roman MT, Toledo D. Ice Giant Circulation Patterns: Implications for Atmospheric Probes. SPACE SCIENCE REVIEWS 2020. [PMID: 32165773 DOI: 10.1007/s11214-019-0619-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Atmospheric circulation patterns derived from multi-spectral remote sensing can serve as a guide for choosing a suitable entry location for a future in situ probe mission to the Ice Giants. Since the Voyager-2 flybys in the 1980s, three decades of observations from ground- and space-based observatories have generated a picture of Ice Giant circulation that is complex, perplexing, and altogether unlike that seen on the Gas Giants. This review seeks to reconcile the various competing circulation patterns from an observational perspective, accounting for spatially-resolved measurements of: zonal albedo contrasts and banded appearances; cloud-tracked zonal winds; temperature and para-H2 measurements above the condensate clouds; and equator-to-pole contrasts in condensable volatiles (methane, ammonia, and hydrogen sulphide) in the deeper troposphere. These observations identify three distinct latitude domains: an equatorial domain of deep upwelling and upper-tropospheric subsidence, potentially bounded by peaks in the retrograde zonal jet and analogous to Jovian cyclonic belts; a mid-latitude transitional domain of upper-tropospheric upwelling, vigorous cloud activity, analogous to Jovian anticyclonic zones; and a polar domain of strong subsidence, volatile depletion, and small-scale (and potentially seasonally-variable) convective activity. Taken together, the multi-wavelength observations suggest a tiered structure of stacked circulation cells (at least two in the troposphere and one in the stratosphere), potentially separated in the vertical by (i) strong molecular weight gradients associated with cloud condensation, and by (ii) transitions from a thermally-direct circulation regime at depth to a wave- and radiative-driven circulation regime at high altitude. The inferred circulation can be tested in the coming decade by 3D numerical simulations of the atmosphere, and by observations from future world-class facilities. The carrier spacecraft for any probe entry mission must ultimately carry a suite of remote-sensing instruments capable of fully constraining the atmospheric motions at the probe descent location.
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Affiliation(s)
- Leigh N Fletcher
- 1School of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH UK
| | - Imke de Pater
- 3Department of Astronomy, University of California, 501 Campbell Hall, Berkeley, CA 94720 USA
| | - Glenn S Orton
- 2Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 USA
| | - Mark D Hofstadter
- 2Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 USA
| | - Patrick G J Irwin
- 4Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Road, Oxford, OX1 3PU UK
| | - Michael T Roman
- 1School of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH UK
| | - Daniel Toledo
- 4Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Road, Oxford, OX1 3PU UK
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Sitnov M, Birn J, Ferdousi B, Gordeev E, Khotyaintsev Y, Merkin V, Motoba T, Otto A, Panov E, Pritchett P, Pucci F, Raeder J, Runov A, Sergeev V, Velli M, Zhou X. Explosive Magnetotail Activity. SPACE SCIENCE REVIEWS 2019; 215:31. [PMID: 31178609 PMCID: PMC6528807 DOI: 10.1007/s11214-019-0599-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 04/27/2019] [Indexed: 06/01/2023]
Abstract
Modes and manifestations of the explosive activity in the Earth's magnetotail, as well as its onset mechanisms and key pre-onset conditions are reviewed. Two mechanisms for the generation of the pre-onset current sheet are discussed, namely magnetic flux addition to the tail lobes, or other high-latitude perturbations, and magnetic flux evacuation from the near-Earth tail associated with dayside reconnection. Reconnection onset may require stretching and thinning of the sheet down to electron scales. It may also start in thicker sheets in regions with a tailward gradient of the equatorial magnetic field B z ; in this case it begins as an ideal-MHD instability followed by the generation of bursty bulk flows and dipolarization fronts. Indeed, remote sensing and global MHD modeling show the formation of tail regions with increased B z , prone to magnetic reconnection, ballooning/interchange and flapping instabilities. While interchange instability may also develop in such thicker sheets, it may grow more slowly compared to tearing and cause secondary reconnection locally in the dawn-dusk direction. Post-onset transients include bursty flows and dipolarization fronts, micro-instabilities of lower-hybrid-drift and whistler waves, as well as damped global flux tube oscillations in the near-Earth region. They convert the stretched tail magnetic field energy into bulk plasma acceleration and collisionless heating, excitation of a broad spectrum of plasma waves, and collisional dissipation in the ionosphere. Collisionless heating involves ion reflection from fronts, Fermi, betatron as well as other, non-adiabatic, mechanisms. Ionospheric manifestations of some of these magnetotail phenomena are discussed. Explosive plasma phenomena observed in the laboratory, the solar corona and solar wind are also discussed.
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Affiliation(s)
- Mikhail Sitnov
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
| | | | | | - Evgeny Gordeev
- Earth’s Physics Department, Saint Petersburg State University, St. Petersburg, Russia
| | | | - Viacheslav Merkin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
| | - Tetsuo Motoba
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
| | | | - Evgeny Panov
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - Philip Pritchett
- Department of Physics and Astronomy, University of California, Los Angeles, CA USA
| | - Fulvia Pucci
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292 Japan
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ USA
| | - Joachim Raeder
- Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH USA
| | - Andrei Runov
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA USA
| | - Victor Sergeev
- Earth’s Physics Department, Saint Petersburg State University, St. Petersburg, Russia
| | - Marco Velli
- University of California Los Angeles, Los Angeles, CA 90095 USA
| | - Xuzhi Zhou
- School of Earth and Space Sciences, Peking University, Beijing, 100871 China
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Varsani A, Nakamura R, Sergeev VA, Baumjohann W, Owen CJ, Petrukovich AA, Yao Z, Nakamura TKM, Kubyshkina MV, Sotirelis T, Burch JL, Genestreti KJ, Vörös Z, Andriopoulou M, Gershman DJ, Avanov LA, Magnes W, Russell CT, Plaschke F, Khotyaintsev YV, Giles BL, Coffey VN, Dorelli JC, Strangeway RJ, Torbert RB, Lindqvist P, Ergun R. Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2017; 122:10891-10909. [PMID: 29399431 PMCID: PMC5784414 DOI: 10.1002/2017ja024547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 09/27/2017] [Accepted: 10/05/2017] [Indexed: 06/07/2023]
Abstract
During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they simultaneously crossed the reconnection separatrix layer during this very intense reconnection event. These include (1) energy dispersion of the energetic ions and electrons traveling earthward, accompanied with high electron energies in the vicinity of the separatrix; (2) energy dispersion of polar rain electrons, with a high-energy cutoff; and (3) intense inward convection of the magnetic field lines at the MMS location. The high temporal resolution measurements by MMS provide unprecedented observations of the outermost electron boundary layer. We discuss the relevance of the energy dispersion of the electrons, and their pitch angle distribution, to the spatial and temporal evolution of the boundary layer. The results indicate that the underlying magnetotail magnetic reconnection process was an intrinsically impulsive and the active X-line was located relatively close to the Earth, approximately at 16-18 RE.
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Affiliation(s)
- A. Varsani
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - R. Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - V. A. Sergeev
- Earth's Physics DepartmentSt. Petersburg State UniversitySt. PetersburgRussia
| | - W. Baumjohann
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - C. J. Owen
- Mullard Space Science Laboratory/UCLDorkingUK
| | | | - Z. Yao
- Space Science Technologies and Astrophysics Research InstituteLiegeBelgium
| | | | - M. V. Kubyshkina
- Earth's Physics DepartmentSt. Petersburg State UniversitySt. PetersburgRussia
| | - T. Sotirelis
- Applied Physics LaboratoryThe Johns Hopkins UniversityBaltimoreMAUSA
| | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | | | - Z. Vörös
- Space Research InstituteAustrian Academy of SciencesGrazAustria
- Institute of PhysicsUniversity of GrazGrazAustria
| | - M. Andriopoulou
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - D. J. Gershman
- Heliophysics Science DivisionNASA Goddard Space Flight CenterGreenbeltMDUSA
| | - L. A. Avanov
- Heliophysics Science DivisionNASA Goddard Space Flight CenterGreenbeltMDUSA
| | - W. Magnes
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - C. T. Russell
- University of California Los Angeles, IGPP/EPSSLos AngelesCAUSA
| | - F. Plaschke
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | | | - B. L. Giles
- Heliophysics Science DivisionNASA Goddard Space Flight CenterGreenbeltMDUSA
| | - V. N. Coffey
- NASA Marshall Space Flight CenterHuntsvilleALUSA
| | - J. C. Dorelli
- Heliophysics Science DivisionNASA Goddard Space Flight CenterGreenbeltMDUSA
| | | | - R. B. Torbert
- Southwest Research InstituteSan AntonioTXUSA
- University of New HampshireDurhamNHUSA
| | | | - R. Ergun
- Laboratory for Atmospheric and Space PhysicsUniversity of Colorado BoulderBoulderCOUSA
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Yao Z, Pu ZY, Rae IJ, Radioti A, Kubyshkina MV. Auroral streamer and its role in driving wave-like pre-onset aurora. GEOSCIENCE LETTERS 2017; 4:8. [PMID: 32215237 PMCID: PMC7067272 DOI: 10.1186/s40562-017-0075-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 04/04/2017] [Indexed: 06/10/2023]
Abstract
The time scales of reconnection outflow, substorm expansion, and development of instabilities in the terrestrial magnetosphere are comparable, i.e., from several to tens of minutes, and their existence is related. In this paper, we investigate the physical relations among those phenomena with measurements during a substorm event on January 29, 2008. We present conjugate measurements from ground-based high-temporal resolution all-sky imagers and in situ THEMIS measurements. An auroral streamer (north-south aligned thin auroral layer) was formed and propagated equatorward, which usually implies an earthward propagating plasma flow in the magnetotail. At the most equatorward part of the auroral streamer, a wave-like auroral band was formed aligning in the east-west direction. The wave-like auroral structure is usually explained as a consequence of instability development. Using AM03 model, we trace the auroral structure to magnetotail and estimate a wavelength of ~0.5 R E. The scale is comparable to the drift mode wavelength determined by the in situ measurements from THEMIS-A, whose footpoint is on the wave-like auroral arc. We also present similar wave-like aurora observations from Cassini ultraviolet imaging spectrograph at Saturn and from Hubble space telescope at Jupiter, suggesting that the wave-like aurora structure is likely a result of fundamental plasma dynamics in the solar system planetary magnetospheres.
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Affiliation(s)
- Zhonghua Yao
- Laboratoire de Physique Atmosphérique et Planétaire, STAR institute, Université de Liège, Liège, Belgium
- School of Earth and Space Sciences, Peking University, Beijing, China
- UCL Mullard Space Science Laboratory, Dorking, RH5 6NT UK
| | - Z. Y. Pu
- School of Earth and Space Sciences, Peking University, Beijing, China
| | - I. J. Rae
- UCL Mullard Space Science Laboratory, Dorking, RH5 6NT UK
| | - A. Radioti
- Laboratoire de Physique Atmosphérique et Planétaire, STAR institute, Université de Liège, Liège, Belgium
| | - M. V. Kubyshkina
- Physics Faculty, St. Petersburg State University, St. Petersburg, Russia
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5
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Panov EV, Baumjohann W, Wolf RA, Nakamura R, Angelopoulos V, Weygand JM, Kubyshkina MV. Magnetotail energy dissipation during an auroral substorm. NATURE PHYSICS 2016; 12:1158-1163. [PMID: 27917231 PMCID: PMC5131847 DOI: 10.1038/nphys3879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 08/04/2016] [Indexed: 06/01/2023]
Abstract
Violent releases of space plasma energy from the Earth's magnetotail during substorms produce strong electric currents and bright aurora. But what modulates these currents and aurora and controls dissipation of the energy released in the ionosphere? Using data from the THEMIS fleet of satellites and ground-based imagers and magnetometers, we show that plasma energy dissipation is controlled by field-aligned currents (FACs) produced and modulated during magnetotail topology change and oscillatory braking of fast plasma jets at 10-14 Earth radii in the nightside magnetosphere. FACs appear in regions where plasma sheet pressure and flux tube volume gradients are non-collinear. Faster tailward expansion of magnetotail dipolarization and subsequent slower inner plasma sheet restretching during substorm expansion and recovery phases cause faster poleward then slower equatorward movement of the substorm aurora. Anharmonic radial plasma oscillations build up displaced current filaments and are responsible for discrete longitudinal auroral arcs that move equatorward at a velocity of about 1km/s. This observed auroral activity appears sufficient to dissipate the released energy.
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Affiliation(s)
- E V Panov
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - W Baumjohann
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - R A Wolf
- Physics and Astronomy Department, Rice University, Houston, Texas, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - V Angelopoulos
- Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, USA
| | - J M Weygand
- Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, USA
| | - M V Kubyshkina
- St. Petersburg State University, St. Petersburg, Russian Federation
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