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Structure of Jupiter's High‐Latitude Storms: Folded Filamentary Regions Revealed by Juno.

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Bibliographic Details
Title:	Structure of Jupiter's High‐Latitude Storms: Folded Filamentary Regions Revealed by Juno.
Authors:	Fletcher, L. N.¹ (AUTHOR) leigh.fletcher@le.ac.uk, Zhang, Z.² (AUTHOR), Brown, S.³ (AUTHOR), Oyafuso, F. A.³ (AUTHOR), Rogers, J. H.⁴ (AUTHOR), Wong, M. H.^5,6 (AUTHOR), Mura, A.⁷ (AUTHOR), Eichstädt, G.⁸ (AUTHOR), Orton, G. S.³ (AUTHOR), Brueshaber, S.⁹ (AUTHOR), Sankar, R.⁵ (AUTHOR), Li, C.¹⁰ (AUTHOR), Levin, S. M.³ (AUTHOR), Biagiotti, F.⁷ (AUTHOR), Guillot, T.¹¹ (AUTHOR), Ingersoll, A. P.² (AUTHOR), Grassi, D.⁷ (AUTHOR), Hansen, C. J.¹² (AUTHOR), Bolton, S.¹³ (AUTHOR), Waite, J. H.¹⁴ (AUTHOR)
Source:	Journal of Geophysical Research. Planets. Jan2026, Vol. 131 Issue 1, p1-31. 31p.
Subject Terms:	Cyclones, Thunderstorms, Jupiter (Planet), Juno (Space probe), Latitude, Convection (Astrophysics), Heat convection
Abstract:	Sprawling, turbulent cloud formations dominate the meteorology of Jupiter's mid‐to‐high latitudes, known as Folded Filamentary Regions (FFRs). A multi‐wavelength characterization by Juno reveals the spatial distribution, vertical structure, and energetics of the FFRs. The cloud tops display multiple lobes of stratiform aerosols, separated by darker, cloud‐free lanes, and embedded with smaller eddies and high‐altitude cumulus clouds. These cyclonic FFRs are microwave‐bright in shallow‐sounding wavelengths (p<5 $p< 5$ bars) and microwave‐dark in deep‐sounding wavelengths (p>10 $p > 10$ bars), with the transition potentially associated with the water condensation layer (6–7 bars). Associating microwave contrasts with temperature anomalies, this implies despinning of cyclonic eddies above/below their mid‐planes. Despite deep roots (being detectable in wavelengths sounding ∼100 ${\sim} 100$ bars), they are "pancake vortices" with horizontal extents at least an order of magnitude larger than their depth. In the northern hemisphere, FFRs are most common in cyclonic belts poleward of 40° $40{}^{\circ}$N (all latitudes are planetocentric), particularly a North Polar Filamentary Belt (NPFB) near 66−70° $66-70{}^{\circ}$N that defines the transition from organized belts/zones to the chaotic polar domain. This distribution explains the high lightning rates from 45−80° $45-80{}^{\circ}$N, peaking in a belt poleward of 52.3° $52.3{}^{\circ}$N, which may trace the availability of water for moist convection. Many observed lightning flashes can be associated to specific FFRs containing bright storms, but some FFRs display no activity, suggesting quiescent periods during storm evolution. Analogies to Earth's oceanic eddies suggest that cyclones deform isentropic surfaces at their midplanes, raising deep water‐rich layers upwards to promote moist convection, release latent heat, and inject clouds into the upper troposphere. Plain Language Summary: Swirls of chaotic, billowing white clouds dominate JunoCam images of Jupiter's mid‐to‐high latitudes, casting shadows against the darker clouds below. Their appearance is reminiscent of filamentary eddies in Earth's oceans, revealed by contrasts in temperature, salinity, and phytoplankton blooms. We use Juno's suite of instruments spanning reflected sunlight (visible) and thermal emission (infrared and microwave) to determine common characteristics and 3D structure of these "Folded Filamentary Regions" (FFRs), finding that they have deep roots (visible down to ∼100 ${\sim} 100$ bars), and display a change from being microwave‐bright (i.e., warm and/or ammonia‐poor) to microwave‐dark (cool and/or ammonia‐rich) as we probe deep below the water cloud. FFRs dominate the weather systems at high latitudes: they are mostly found in Jupiter's belts (particularly those suspected to have the largest availability of water), and are often associated with lightning, explaining the high rates of flashes and sferics detected at high latitudes. FFRs form a "North Polar Filamentary Belt" that marks the transition into the polar domain. These cyclonic eddies may be the key driver for Jupiter's moist convective eruptions, and thus lightning, latent heat release, and internal heat flux at high latitudes. Key Points: Jupiter's Folded Filamentary Regions (FFRs) dominate the appearance and lightning activity of cyclonic beltsFFRs change from being microwave‐bright at shallow pressures, to microwave‐dark below the water cloud, and are detected to at least 100 barFFRs promote moist convection and are the main source of lightning, particularly in belts near 52−57°N and poleward of 66° $66{}^{\circ}$N [ABSTRACT FROM AUTHOR]
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Description
Abstract:	Sprawling, turbulent cloud formations dominate the meteorology of Jupiter's mid‐to‐high latitudes, known as Folded Filamentary Regions (FFRs). A multi‐wavelength characterization by Juno reveals the spatial distribution, vertical structure, and energetics of the FFRs. The cloud tops display multiple lobes of stratiform aerosols, separated by darker, cloud‐free lanes, and embedded with smaller eddies and high‐altitude cumulus clouds. These cyclonic FFRs are microwave‐bright in shallow‐sounding wavelengths (p<5 $p< 5$ bars) and microwave‐dark in deep‐sounding wavelengths (p>10 $p > 10$ bars), with the transition potentially associated with the water condensation layer (6–7 bars). Associating microwave contrasts with temperature anomalies, this implies despinning of cyclonic eddies above/below their mid‐planes. Despite deep roots (being detectable in wavelengths sounding ∼100 ${\sim} 100$ bars), they are "pancake vortices" with horizontal extents at least an order of magnitude larger than their depth. In the northern hemisphere, FFRs are most common in cyclonic belts poleward of 40° $40{}^{\circ}$N (all latitudes are planetocentric), particularly a North Polar Filamentary Belt (NPFB) near 66−70° $66-70{}^{\circ}$N that defines the transition from organized belts/zones to the chaotic polar domain. This distribution explains the high lightning rates from 45−80° $45-80{}^{\circ}$N, peaking in a belt poleward of 52.3° $52.3{}^{\circ}$N, which may trace the availability of water for moist convection. Many observed lightning flashes can be associated to specific FFRs containing bright storms, but some FFRs display no activity, suggesting quiescent periods during storm evolution. Analogies to Earth's oceanic eddies suggest that cyclones deform isentropic surfaces at their midplanes, raising deep water‐rich layers upwards to promote moist convection, release latent heat, and inject clouds into the upper troposphere. Plain Language Summary: Swirls of chaotic, billowing white clouds dominate JunoCam images of Jupiter's mid‐to‐high latitudes, casting shadows against the darker clouds below. Their appearance is reminiscent of filamentary eddies in Earth's oceans, revealed by contrasts in temperature, salinity, and phytoplankton blooms. We use Juno's suite of instruments spanning reflected sunlight (visible) and thermal emission (infrared and microwave) to determine common characteristics and 3D structure of these "Folded Filamentary Regions" (FFRs), finding that they have deep roots (visible down to ∼100 ${\sim} 100$ bars), and display a change from being microwave‐bright (i.e., warm and/or ammonia‐poor) to microwave‐dark (cool and/or ammonia‐rich) as we probe deep below the water cloud. FFRs dominate the weather systems at high latitudes: they are mostly found in Jupiter's belts (particularly those suspected to have the largest availability of water), and are often associated with lightning, explaining the high rates of flashes and sferics detected at high latitudes. FFRs form a "North Polar Filamentary Belt" that marks the transition into the polar domain. These cyclonic eddies may be the key driver for Jupiter's moist convective eruptions, and thus lightning, latent heat release, and internal heat flux at high latitudes. Key Points: Jupiter's Folded Filamentary Regions (FFRs) dominate the appearance and lightning activity of cyclonic beltsFFRs change from being microwave‐bright at shallow pressures, to microwave‐dark below the water cloud, and are detected to at least 100 barFFRs promote moist convection and are the main source of lightning, particularly in belts near 52−57°N and poleward of 66° $66{}^{\circ}$N [ABSTRACT FROM AUTHOR]
ISSN:	21699097
DOI:	10.1029/2025JE009315