The visible spectrum of Jupiter contains absorption bands of methane (619 nm) and ammonia (647 nm) that can be used to probe the cloud-top pressures and ammonia abundance in Jupiter's atmosphere. Recently, it has been shown that filter-averaged observations of Jupiter made with telescopes and filters accessible to backyard astronomers can be reduced to yield ammonia maps that bear a remarkable similarity with distributions derived using more complex radiative transfer methods. Here, we determine the reliability of this method by applying it to observations made with the MUSE instrument at ESO's Very Large Telescope, and find excellent correspondence with the retrieved products from multiple-scattering retrieval model analyses. We find that the main level of reflection in Jupiter's atmosphere is at 2-3 bar, which is far beneath the anticipated ammonia ice condensation level at similar to ${\sim} $ 0.7 bar, and conclude that pure ammonia ice cannot be the main cloud constituent. We show that the spatial variations of ammonia determined at 2-3 bar are strongly correlated with those determined from thermal-infrared observations, and microwave observations by the Very Large Array and the Juno spacecraft. Finally, we show that the same technique can be applied to observations of Saturn, again yielding maps of ammonia abundance at 2-3 bar that are well-correlated with thermal-IR observations made near 5 mu $\mu $m by Cassini/VIMS and JWST/MIRI. Similarly, the main level of reflectivity is found to be lie far beneath the expected condensation level of ammonia in Saturn's atmosphere at similar to ${\sim} $ 1.8 bar.

AbstractIn the first 20 orbits of the Juno mission, over 150 waves and wave-like features have been detected by the JunoCam public-outreach camera. A wide variety of wave morphologies were detected over a wide latitude range, but the great majority were found near Jupiter’s equator. By analogy with previous studies of waves in Jupiter’s atmosphere, most of the waves detected are likely to be inertia-gravity waves.The Juno mission’s JunoCam instrument [1], has detected very small-scale waves. Our survey of JunoCam images revealed a surprising variety of features with wave-like morphologies. They are presented in terms of differences in visual morphology, without implication that this differentiation arises from the associated responsible dynamics.Long wave packets with short, dark wave fronts represent 79% of the types of waves in our inventory, especially in the Equatorial Zone (EZ) that were also detected in previous studies. These include wave trains with orthogonal wave crests. Even more commonly, we detected wave packets with tilted fronts that are not oriented orthogonally to the wave packet direction. Both the meridional extent and wavelength of these waves are much shorter than the Rossby deformation radius, so it is logical to assume that they are formed by and interact with small-scale turbulence, and thereby propagate the waves in all directions (Fig. 1). Sometimes the short wavefronts are aligned in curved wave packets, all associated with larger features, and located outside the EZ. Short wave packets with wide wave fronts were also detected. In the Earth’s atmosphere, such waves are often associated with thunderstorms producing a brief impulse period with radiating waves.Wave packets with bright features appear bright on a dark background rather than dark on a lighter background, like the waves described above. Differences between darker and brighter wave crests could be the composition of the material affected.Lee waves, stationary waves generated by the vertical deflection of winds over an obstacle, were also detected. Jupiter’s atmosphere no doubt possesses the dynamical equivalent of an obstacle (Fig. 2).Waves associated with large vortices include compact cyclonic and anticyclonic features with extended radial wavefronts, resembling structures in terrestrial cyclonic hurricanes (Fig. 3). Long, parallel dark streaks are seen both with a non-uniform patterns and in regularly spaced parallel bands. Their orientation suggests that they are tracing out the direction of flow on streamlines. Figure 4 plots the distribution of mean wavelengths for different types of waves and wave-like features as a function of latitude, co-plotted with mean zonal wind velocity. The minimum distance between crests is 29.1 km. The variability of wavelengths within a single packet is typically no greater than 20-30%. The equatorial waves with long packets and short crests in the EZ have wavelengths that are clustered between 30 km and 320 km, with most between 80 and 230 km in size. No waves are found at latitudes associated with retrograde zonal flow unless associated with a larger atmospheric feature.JunoCam, detected 157 waves or wave-like features in its first 20 perijove passes. Of these, 100 are waves with long, linear packets and short crests. Another 25were detected with short packets and long crests. They are all likely to be truly propagating waves, which form the vast majority of features detected, concentrated in a latitude range between 5ºS and 7ºN. Few of these appear to be associated with other features except for waves that appear to be oriented in lines of local flow. There were fewer waves in the EZ between the equator and 1ºN than there were immediately north and south of this band, which was different from the waves detected by Voyager imaging in 1979 that were more equally distributed. Other waves outside the EZ are influenced by other features. These include waves associated with an anticyclonic or cyclonic eddies, lee waves some 10 km above the surrounding cloud deck. Several features appeared within or emanating from vortices. Two sets of extremely long, curved features were detected near the edges of a southwestern extension of a region associated with high 5-µm radiances at the southern edge of the NEB. No waves were detected south of 7ºS that were not associated with larger vortices, such as the GRS. No waves or wave-like features were detected in regions of retrograde mean zonal flow that were not associated with larger features, similar to the waves detected by Voyager imaging.AcknowledgementsThe primary support for this research was provided by NASA, a portion of which was distributed to the Jet Propulsion Laboratory, California Institute of Technology. References [1] Hansen et al. Junocam: Juno’s outreach camera. Space Sci. Rev. 217, 475-506. 2017.[2] Wong et al. High-resolution UV/optical/IR imaging of Jupiter in 2016–2019. Space Sci. Rev. 247, 58. 2020.

Introduction The extended portion of NASA’s Juno mission began on 1 August 2021 and will continue through September 2025. The extended mission expands Juno’s science goals beyond those of the prime mission, as noted at the last EPSC (Orton et al. EPSC2021-58). Atmospheric studies will continue to be among the foremost of science goals and an area in which the world-wide community of Jupiter observers can provide significant contextual support. Juno’s remote-sensing observations will take advantage of the migration of its closest approaches (“perijoves” or PJs) toward increasingly northern latitudes. The observations should include close-ups of the circumpolar cyclones and semi-chaotic cyclones known as “folded filamentary regions”. A series of radio occultations will provide vertical profiles of electron density and the neutral-atmospheric temperature over several atmospheric regions. The mission will also map the variability of lightning on Jupiter’s night side. Physical Details of the Mission The sequence of orbits and key investigations of the primary and extended missions are shown in Figure 1. We note that on PJ34, the orbital period was reduced from 53 days to 43-44 days. It will be reduced shortly after this meeting on PJ45 to 38 days and again on PJ57 to ~33 days. Figure 1. Progression of Juno orbits viewed from above Jupiter’s north pole with respect to local time of day. “PJ” designates a “perijove”, the closest approach to Jupiter on each numbered orbit. Following a Ganymede flyby on PJ34 (green orbit), the orbital period decreased from 53 days to 43-44 days (green + blue orbits). The “Great Blue Spot” (blue) orbits map an isolated patch of intense magnetic field. Following a close Europa flyby on PJ45 (aqua orbit), the period will decrease to ~38 days (orange orbits). Following close flybys of Io on PJ57 and PJ58 (black orbits) the period will decrease to ~33 days (red orbits). In reflected sunlight, Jupiter will mostly appear as a crescent at perijoves following PJ58. Some characteristics of perijoves of the extended mission are shown in Table 1. We caution that while the day of year for the perijoves is reasonably fixed, the exact times may change by hours in either direction and the longitudes will change accordingly. Timing for later orbits up to PJ76, may be affected by currently unmodeled anomalies in satellite masses that could change dates and times. Figure 2. Expected latitudes and longitudes to be measured by the 20 radio occultations of the Juno spacecraft between PJ52 and PJ77. Locations of ingress lie largely in the northern hemisphere - locations of egress in the southern hemisphere. Locations of the Galileo Probe and Voyager-1 radio occultations are also shown for reference. Role of Amateur Astronomers We’ve noted in the past at previous EPSC meetings how amateurs can contribute to the Juno mission via their collective world-wide 24/7 coverage of Jupiter. This applies also to the cadre of professional astronomers supporting the Juno mission and its reconnaissance of the Jupiter system over a broad spectral range. In the past, these have alerted observers to strong interactions between the Great Red Spot and smaller anticyclones (Sanchez-Lavega et al. 2021. J. Geophys. Res. 126, e006686) and the occurrence and evolution of prominent and unusual vortices, such as “Clyde’s spot” (Hueso et al. 2022. Icarus 380,114994). During the last apparition, observations were made with the NASA Infrared Telescope Facility (IRTF) that showed slow-moving bright patches in the Equatorial Zone (EZ) that were observed more continuously among the amateur community with 890-nm (“methane”) filters. We also identified an intense 5-µm spot detected using IRTF imaging that coincided with an unusually dark spot in amateur methane-filtered images. The continued tracking of outbreaks in the southern part of the North Equatorial Belt (NEB) also greatly informed the Juno team and supporting astronomers regarding the systematic longitudinal distribution of outbreaks and the range of atmospheric features they generate. A perijove-by-perijove summary of Juno-supporting observations – past, current and planned - is available at the following web site: https://www.missionjuno.swri.edu/planned-observations. We want to emphasize that by PJ50, Juno’s perijoves will have migrated to a part of the planet that is not in sunlight. At that point and through the end of the mission, images from this community will be extremely useful to order to provide a context for several investigations. One of these will be chief on JunoCam’s agenda during this part of the mission: searches for lightning. But similar contextual information will be sought for measurements of thermal emission from the JIRAM instrument’s high-resolution maps of 5-µm emission, as well as the Microwave Radiometer (MWR) measurements of thermal emission from the deep atmosphere. Although the highest spatial resolution from these instruments will include high northern latitudes (see Table 1) that are not well resolved by small telescopes, measurements of mid-northern latitudes will continue to be made when JunoCam will not be able to provide a visual context. Table 1. Current estimates for Juno extended mission perijoves PJ45-PJ53. Timing for orbits PJ54 onward may be affected by currently unmodeled anomalies in satellite masses that could change dates and times. Accordingly we list perijove times to the nearest half hour and longitudes to the nearest 10°. Orton et al. (EPSC2021-58) presented information for previous perijoves.

We study how the transmission of monetary policy to firms' investment and credit spreads depends on their financial conditions, finding a major role for their excess bond premia (EBPs), the component of credit spreads in excess of default risk. While monetary policy easing shocks compress credit spreads more for firms with higher ex-ante EBPs, it is lower-EBP firms that invest more. We rationalize these findings using a model with financial frictions in which lower-EBP firms have flatter marginal product of capital curves. We also show empirically that the cross-sectional distribution of firm EBPs determines the aggregate effectiveness of monetary policy.

Juno has observed the circumpolar cyclones (CPCs) on Jupiter with the visible-light camera, JunoCam, and the 2-5 µm infrared JIRAM camera, since orbit insertion.  The CPCs have distinctive cloud features, and unique characteristics that broadly classify into two morphological forms, chaotic and filled.  As revealed by JunoCam, the filled CPCs typically appear with large bright cloud features on the periphery, similar in appearance to a circular saw blade.  Just inward of those, nearly uniform darker regions appear---probably stratiform clouds---occasionally displaying small hole-like openings, which appear bright at 5 μm. The overall appearance of the periphery and just inward is reminiscent of shear-like instability in the flow. Anticyclonic circulation has been witnessed in the center of several filled CPCs. Lightning has also been observed by JunoCam in one of the blade-like cloud features at perijove 31, and we occasionally observe thin, bright curvilinear cloud features and clusters of bright clouds with shadows indicating vertical structure. The chaotic CPCs, including the central cyclone, have a different morphology, however, appearing as a flocculent and tightly wrapped series of alternatively bright and dark spirals. Interestingly, CPC #2 has partially transformed from a chaotic morphology into a filled morphology, similar perhaps to how oval cyclones and barges in the low latitudes can sometimes transform into folded-filamentary cyclones (e.g., Clyde’s Spot). Here, we discuss each CPC and the central cyclone throughout the course of the mission thus far. We primarily use images captured by JunoCam and JIRAM, but we note that the MWR is now resolving the CPCs (see separate abstract), providing additional clues on their vertical structure. This work is an attempt to document the morphology of the CPCs and their changes for future modeling attempts to replicate them in detail, which, in turn, may provide additional insight into their formation, evolution, and stability.

AbstractCurrent understanding of the ammonia distribution in Jupiter's atmosphere is provided by observations from major ground‐based facilities and spacecraft, and analyzed with sophisticated retrieval models that recover high fidelity information, but are limited in spatial and temporal coverage. Here we show that the ammonia abundance in Jupiter's upper troposphere, which tracks the overturning atmospheric circulation, can be simply, but reliably determined from continuum‐divided ammonia and methane absorption‐band images made with a moderate‐sized Schmidt‐Cassegrain telescope (SCT). In 2020–2021, Jupiter was imaged in the 647‐nm ammonia absorption band and adjacent continuum bands with a 0.28‐m SCT, demonstrating that the spatially resolved ammonia optical depth could be determined with such a telescope. In 2022–2023, a 619 nm methane‐band filter was added to provide a constant reference against which to correct the ammonia abundances (column‐averaged mole fraction) for cloud opacity variations. These 0.28‐m SCT results are compared with observations from: (a) the MUSE instrument on ESO's Very Large Telescope (b) the TEXES mid‐infrared spectrometer used on NASA's InfraRed Telescope Facility; and (c) the Gemini telescopes, and are shown to provide reliable maps of ammonia abundance. Meridional and longitudinal features are examined, including the Equatorial Zone (EZ) ammonia enhancement, the North Equatorial Belt depletion, depletion above the Great Red Spot, and longitudinal enhancements in the northern EZ. This work demonstrates meaningful ammonia monitoring can be achieved with small telescopes that can complement spacecraft and major ground‐based facility observations.

We construct a newspaper-based index of U.S.-China tension (UCT) that shows close alignment with the views expressed by business and policy decision makers, both in rhetoric and action. We document that elevated tension is associated with reduced U.S. corporate investment---especially for firms that are more exposed to China---and reconfiguration of U.S. firm supply chains away from China. U.S.-China tension is also reflected in cross-sectional U.S. stock returns. These effects predate the 2018 trade disputes. We show that transmission channels operate through both tension actions and uncertainty surrounding those actions, with the uncertainty channel being more important.

Introduction The Juno mission has given the first opportunity to characterise the flow patterns in Jupiter’s south polar region (SPR). Fast winds can be measured by comparing hi-res JunoCam images over up to 2 hours within a single pass, which shows in detail the motion of the southernmost jet at 64ºS (all latitudes planetocentric), and the circulations of cyclonic folded filamentary regions (FFRs) and anticyclonic white ovals (AWOs) further south [1]. However, Juno data cannot trace slower motions, in particular the drifts of these coherent circulations over days to months. Over the 53-day interval between perijoves a few AWOs can be recognised, but the interval is too long to recognise individual FFRs, which are the dominant structures of this region. The best amateur ground-based images now have sufficient resolution to identify and track some of these features. Here, we use maps and measurements from amateur images in 2016-2020, combined with JunoCam maps that provide secure identification of the features. Thus we find that pale patches in ground-based images usually represent FFRs in Juno maps, and some small light spots are AWOs. Measurements of drifts of FFRs over days (e.g. Fig.1) From hi-res images by several amateur observers, we made south polar projection maps using WinJUPOS [2]. From blinking and animating these maps, we find that features in the SPR could only be tracked using v-hi-res images at intervals of less than 5 days; FFRs cannot be confidently identified over longer gaps as they change shape and position rapidly, although they may last for weeks. With maps spaced by 2-4 days, it is possible to observe their zonal motions and changes in outline. This is best done within a few days of a Juno perijove so that the features can be identified in the Juno map. We selected several short series of maps in 2018 April-May and 2020 April-June that gave the clearest results, mostly using I-band images by A.C. as these were most consistent. Preliminary results show: --Features at ~60-65ºS are prograding (around the S6 jet at 64ºS). --Features at ~66-74ºS are retrograding (including FFRs in the belt), with speeds comparable to those of the AWOs (see below). -- Around 66ºS, where JunoCam images often show FFRs in the belt apparently extending north towards the S6 jet, they can sometimes be observed being sheared accordingly, with the north part of the FFR prograding close to the jet (e.g. Fig.1). Measurements of drifts of AWOs at ~70-74ºS over weeks to months The JunoCam maps (e.g. Fig.1) show several AWOs in this latitude range at every perijove. We have tracked these white ovals from 2016 to 2018 using positions from JunoCam (our maps) and ground-based images (measurements and maps by the JUPOS team) plus a few from HST (OPAL maps). Fig.2 shows part of the chart. The largest AWO (A) has been tracked from 2015 (pre-Juno) to 2020. Some other ovals have probably existed for at least 8 months each, regardless of latitude, although small ones cannot always be tracked between perijoves. Some ovals have merged or disappeared within the first two years of the Juno coverage. Others are seen passing each other in different latitudes in Juno maps, although we cannot tell which is which thereafter. There are also even smaller AWOs and eddies, so there may be rapid turnover by growth, wandering in latitude, and mergers or disappearance. The resulting zonal drift profile (ZDP) is in Fig.3. These AWOs move with essentially uniform retrograde flow from 69.5-72.4ºS, [in L3, +42 (±3) deg/53d, -3.8 to -3.2 (±0.25) m/s], but at higher latitudes, above 72.4ºS, they show a steep gradient to faster (prograding) speeds. The highest-latitude and fastest speeds (spots P & E’: Fig.3) are close to those of small AWOs that drift irregularly around the periphery of the south polar pentagon of cyclones at ~80ºS [3]. There we found one shift of -44 deg in 53d, and several of ~-29 deg in 53d. Conclusions The main belt of FFRs is retrograding, along with the AWOs on its S edge. On its N edge, disturbance from FFRs often extends north to the S6 jet and is entrained by the prograding jet. The ZDP (Fig.3) resembles that of high-latitude northern domains (N4, N5)[4], so the belt of FFRs and the loose ring of AWOs just south of it partially retain the organised structure of regular domains, although unconfined towards the pole. South of 73ºS, long-term zonal drifts of AWOs become prograding with a steep gradient of mean speed increasing towards higher latitudes, where it becomes comparable to drifts of AWOs around the polar pentagon. A companion abstract in the OPS1 session [1] describes the short-term wind measurements derived from the JunoCam maps at individual perijoves. References 1. J.H. Rogers et al.(2020) EPSC abstract: ‘Jupiter’s south polar region (~60-80ºS): Wind patterns from JunoCam maps.’ 2. A. Casely & J.H. Rogers (2019). EPSC Abstracts Vol. 13, EPSC-DPS2019-497. ‘Amateur mapping of Jupiter's southern high latitudes to support JunoCam between Perijoves 12-15.’ 3. F. Tabataba-Vakili, J.H. Rogers, G. Eichstädt, G.S. Orton, C.J. Hansen, T.W. Momary, J.A. Sinclair, R.S. Giles, M.A. Caplinger, M.A. Ravine, S.J. Bolton. ‘Long-term tracking of circumpolar cyclones on Jupiter from polar observations with JunoCam.’ Icarus 335 (2020), paper 113405 (online 2019). 4. J. Rogers, G. Adamoli, M. Jacquesson, M. Vedovato, & H-J. Mettig (2017), ‘Jupiter’s high northern latitudes: patterns and dynamics of the N3 to N6 domains.’ https://britastro.org/node/11328 Figure 1. Examples of maps used for tracking FFRs in 2018.

Using images at multiple mid-infrared wavelengths, acquired in May 2018 using the VISIR instrument on ESO's Very Large Telescope (VLT), we study Jupiter's pole-to-pole thermal, chemical and aerosol structure in the troposphere and stratosphere. We confirm that the pattern of cool and cloudy anticyclonic zones and warm cloud-free cyclonic belts persists throughout the mid-latitudes, up to the polar boundaries, and evidence a strong correlation with the vertical maximum windshear and the locations of Jupiter's zonal jets. At high latitudes, VISIR images reveal a large region of mid-infrared cooling poleward $\sim$64$^{\circ}$N and $\sim$67$^{\circ}$S extending from the upper troposphere to the stratosphere, co-located with the reflective aerosols observed by JunoCam, and suggesting that aerosols play a key role in the radiative cooling at the poles. Comparison of zonal-mean thermal properties and high-resolution visible imaging from Juno allows us to study the variability of atmospheric properties as a function of altitude and jet boundaries, particularly in the cold southern polar vortex. However, the southern stratospheric polar vortex is partly masked by a warm mid-infrared signature of the aurora. Co-located with the southern main auroral oval, this warming results from the auroral precipitation and/or joule heating which heat the atmosphere and thus cause a significant stratospheric emission. This high emission results from a large enhancement of both ethane and acetylene in the polar region, reinforcing the evidence of enhanced ion-related chemistry in Jupiter's auroral regions.

Emerging markets and developing economies (EMDEs) exhibit significantly greater volatility in asset returns than advanced economies. The commonalities in these returns (and flows) across countries are particularly strong for EMDEs. If these occur independently of the exchange rate regime and if these global financial cycle effects are furthermore independent of countries' financial openness, the result is Obstfeld (2022)'s "Lemma": countries can do nothing to decouple from the global financial cycle. Under the prevalent view that U.S. monetary policy is the key driver of the global financial cycle, countries then inherit U.S. monetary policy no matter what they do on exchange rates or capital control policies. Using structural vector autoregression models for 78 countries over 1995–2019, as well as different methods of identifying U.S. monetary policy shocks from the literature, this paper tests the proposition that countries with less open capital accounts exhibit systematically smaller responses to U.S. monetary policy shocks than low capital control countries. This paper also considers the role of other institutional features such as exchange rate regimes and foreign exchange interventions in explaining cross-country differences in the responses to the shocks. The empirical results suggest that more stringent capital controls exhibit smaller responses of interest rates and exchange rates to U.S. monetary policy shocks and that this result holds more firmly for EMDEs than advanced economies. In contrast, the analysis finds only weak evidence that the degree of exchange rate flexibility affects U.S. spillovers to foreign interest rates and exchange rates.

This paper provides a comprehensive survey of existing measures of uncertainty, risk, and volatility, noting their conceptual distinctions. It summarizes how they are constructed, their relative advantages in usage, and their effects on financial market and economic outcomes. The measures are divided into four categories based on the construction methodology: news-based, survey-based, econometric-based, and market-based measures. While heightened uncertainty is typically associated with negative real and financial outcomes, the magnitude of these effects and the interpretation of transmission channels crucially depend on identification considerations.

Optical bandpass-filter observations can be simply processed to determine similar horizontal ammonia distributions above the Jovian cloud tops as mid-infrared and microwave observations. Current understanding of this distribution and its relationship to aerosol opacity, cloud-top pressure, and circulation is provided by atmospheric retrieval models using observations from major ground-based facilities and spacecraft. These techniques recover high fidelity information on the ammonia distribution but are limited in spatial and temporal coverage. Part of this coverage gap - upper tropospheric abundance - can be bridged by using continuum-divided ammonia and methane absorption images as suggested by Combes and Encrenaz [1979]. In 2020-21, Jupiter was imaged in the 645 nm ammonia absorption band and adjacent continuum bands, demonstrating that the spatially-resolved optical depth in that band could be determined with a 0.28-m Schmidt-Cassegrain telescope (SCT). In 2022, a 620 nm filter was added to include methane absorption images in the same wavelength range. Methane abundance provides a constant reference against which to determine the ammonia abundance, specifically the column-averaged mole fraction above the clouds. VLT/MUSE results are compared to these SCT results and those from the TEXES mid-infrared spectrometer used on the IRTF and the Gemini telescopes. Meridional and longitudinal features are examined, including the Equatorial Zone (EZ) ammonia enhancement, the North Equatorial Belt (NEB) depletion, depletion above the Great Red Spot (GRS), and suggested enhancements over bright plumes in the northern EZ. This work demonstrates meaningful ammonia monitoring that can provide synoptic coverage and continuity between spacecraft or major ground-based facility campaigns.

Introduction and Summary The ongoing collaboration between amateur observers and the NASA JunoCam team is yielding insights into phenomena of Jupiter’s North Equatorial Belt (NEB), which in 2021 underwent rarely-seen, radical transformations in its appearance, activity, and jet speed. Many of these changes reprise what occurred in 2011-12, and we expect that the present phenomena will clarify how a ‘NEB Revival’ develops and how diverse they can be. NEB Revivals occurred frequently until 1926; but since then, the belt has shown only more modest variations (‘NEB expansion events’), with rapid broadening to the north accompanied by internal convective (‘rifting’) activity. These have occurred every 3-5 years since 1987 [refs.1&4]. In one such cycle, in 2011-12, the visible dark belt became much narrower than usual then underwent the first NEB Revival since 1926 [refs.1-3]. Unfortunately, most of the activity occurred during solar conjunction. In 2021, the visible belt has again shrunk to a narrow south component [NEB(S)]; very dark cyclonic ‘barges’ persist in the whitened northern NEB; and the NEBs jet has accelerated to ‘super-fast’ speeds as the usual NEBs dark formations (NEDFs or ‘hot spots’) have disappeared. But unlike 2011, there have been outbreaks of small bright plumes in the NEB(S), which perturb the adjacent belt. Fading and quiescence of the belt A typical NEB expansion event, with vigorous rifting, occurred in the first half of 2020. The activity subsided in Oct.-Dec. In 2021 April, the NEB had the classic appearance a year after its expansion event (Figure 1): the expanded NEBn edge was partially faded again, and a prominent array of anticyclonic white ovals (AWOs) and dark brown ‘barges’ had developed. Then the NEB rapidly faded, and by late August 2021 it was very faint apart from the very narrow, dark reddish-brown NEB(S), and the dark barges. The belt was also very quiet, with none of the usual rifting, and the NEDFs had become very subdued. JunoCam images confirmed that the scale of turbulence progressively diminished in the later stages of the NEB expansion event, to perijove 34 (PJ34, 2021 June): large rifts give way to smaller-scale, complex rifting texture, and then to very small eddies (Figure 2). This trend proceeded even further as the belt faded (Figure 2). At PJ36 and thereafter, the whitish cloud cover of the faded NEB has a strange texture of faint sinuous haze bands with little indication of the usual wind gradient. Two types of low-contrast waves are also visible in some JunoCam images in the quiescent northern NEB from PJ34 to PJ39: (i) Diffuse, roughly meridional bands at 12-16°N, with wavelengths ~1100-1450 km. (ii) Mesoscale waves, with wavelengths <200 km. Acceleration of the NEBs jet and disappearance of NEDFs As the NEB rifting activity declined, by 2021 June most of the usual NEDFs had become ill-defined and less conspicuous. The last ones disappeared in August, and around that time, much faster tracks appeared on the JUPOS chart (Figure 3), representing smaller features on the NEBs. In Nov-Dec., fast speeds were seen all around the NEBs, with drift in L1 (DL1) ranging from -51 to -79 deg/30d (u = 130-143 m/s). Thus the NEBs jet has accelerated to ‘super-fast’ speed, as it did in 2011 [refs.1&2]. Bright outbreaks in NEB(S) With the NEB generally quiescent, small short-lived localised convective outbreaks in the dark NEB(S) have attracted attention. These are quite common in normal circumstances but especially notable in 2021-22. The first two occurred in 2021 May, then others occurred roughly monthly from August, and more frequently in Dec. (Figure 4). A typical outbreak begins with a small brilliant white spot in the NEB(S) at ~10°N. After about a week it extends tenuous white streaks, and the dark brown NEB(S) may become broadened following the plume, and an extremely methane-dark spot appears nearby (Figure 5). Initially the plume is retrograding (DL1 ≈ +1 to +2 deg/day), but then it moves south to the NEBs edge and becomes prograding (DL1 ≈ –1 to -2 deg/day). All the outbreaks have occurred within a restricted longitude sector with DL1 ~ +0.4 to +1.7 deg/day (Figure 4). The latter speed would be appropriate for a disturbance in the observed latitude of ~10°N. The visible appearance suggests that each outbreak begins with the eruption of a convective plume, and this leads to adjacent downdrafts (creating a clear deep hole that is methane-dark) and a disturbed wake (white streaks and reddish-brown belt). The methane-dark patches maintain the slow speed at 9°N, so they may be persistent waves like the usual NEDFs. The JunoCam images at PJ38 and PJ39 fortunately captured all the types of feature in these outbreaks (Figure 6): (i) Bright active outbreaks were a thick mass of bright white clouds, probably the top of powerful convective storms with hazes expanding from them. Wakes of whitish haze were seen, containing mesoscale waves at PJ39. (ii) NEBs festoons with super-fast speed showed long streaks and cross-cutting orange haze bands, consistent with deep-seated features, although these aspects may not be diagnostic. (iii) Methane-dark patches were viewed suboptimally but could also be deep features. Such an outbreak initiated the NEB Revival in 2012 [ref.3]. We will report on developments during 2022. Acknowledgements: Some of this research was funded by NASA. A portion of this was distributed to the Jet Propulsion Laboratory, California Institute of Technology. References: 1. Rogers JH (2019) J.Brit.Astron.Assoc. 129, 13-26: ‘Jupiter’s North Equatorial Belt and Jet: I. Cyclic expansions and planetary waves.’ 2. ibid. pp.94-102: ‘II. Acceleration of the jet and the NEB Fade in 2011-12.’ 3. Rogers JH & Adamoli G (2019) ibid. pp. 158-169. ‘III. The ‘great northern upheaval’ in 2012.’ [Available at: https://britastro.org/node/15627 (preprints & abstracts) & https://britastro.org/node/7229 (published PDFs).] 4. Rogers JH et al. (2019) ‘The cyclic expansions of Jupiter’s North Equatorial Belt in 2015-2017.’ EPSC Abstracts Vol. 13, EPSC-DPS2019-302 (2019). Full details are available on the BAA Jupiter Section web site and the ALPO-Japan web site.

On May 31, 2020 a short-lived convective storm appeared in one of the small cyclones of Jupiter's South Temperate Belt (STB) at planetographic latitude 30.8°S. The outbreak was captured by amateur astronomer Clyde Foster in methane-band images, became widely known as Clyde's Spot, and was imaged at very high resolution by the Junocam instrument on board the Juno mission 2.5 days later. Junocam images showed a white two-lobed cyclonic system with high clouds observed in the methane-band at 890 nm. The storm evolved over a few days to become a dark feature that showed turbulence for months, presented oscillations in its drift rate, and slowly expanded, first into a Folded Filamentary Region (FFR), and later into a turbulent segment of the STB over a timescale of one year. On August 7, 2021, a new storm strikingly similar to Clyde's Spot erupted in a cyclone of the STB. The new storm exhibited first a similar transformation into a turbulent dark feature, and later transformed into a dark cyclone fully formed by January 2022. We compare the evolution into a FFR of Clyde's Spot with the formation of a FFR observed by Voyager 2 in 1979 in the South South Temperate Belt (SSTB) after a convective outburst in a cyclone that also developed a two-lobed shape. We also discuss the contemporaneous evolution of an additional cyclone of the STB, which was similar to the one were Clyde's Spot developed. This cyclone did not exhibit visible internal convective activity, and transformed from pale white in 2019, with low contrast with the environment, to dark red in 2020, and thus, was very similar to the outcome of the second storm. This cyclone became bright again in 2021 after interacting with Oval BA. We present observations of these phenomena obtained by amateur astronomers, ground-based telescopes, Hubble Space Telescope and Junocam. This study reveals that short-lived small storms that are active for only a few days can produce complex long-term changes that extend over much larger areas than those initially covered by the storms. In a second paper [Iñurrigarro et al., 2022] we use the EPIC numerical model to simulate these storms and study moist convection in closed cyclones.

* Introduction and Summary Jupiter’s troposphere is divided by eastward (prograding) jets into dynamical domains, which we number sequentially (Figure 1) so the highest-latitude northern domains are N4, N5 and N6 (Figure 2). Here we describe characteristics of these domains with short- and long-term tracking of features that can be identified in JunoCam images. Anticyclonic white ovals (AWOs) and cyclonic folded filamentary regions (FFRs) were tracked in 2021 and earlier years, using amateur images (analysed in the JUPOS project; e.g. Figure 3) and JunoCam maps (from the imager on NASA’s Juno orbiter; e.g. Figure 4) and several Hubble maps (from the OPAL project: ref.1). The N6 domain is narrow and corresponds to a largely bland zone in JunoCam maps; all features in it are rapidly prograding. The N4 and N5 domains are broad and chaotic with numerous large FFRs and smaller vortices. Their zonal wind profiles (ZWPs) are dominated by the drifts of AWOs and FFRs, but faster retrograde winds exist in the FFRs. Northerly AWOs have rapid prograde drifts, but these often change suddenly, sometimes due to interactions with FFRs or with other AWOs. Most remarkably, in 2021-22 we have one or (very likely) two examples of AWOs moving south to cross prograde jets: one from the N4 domain and one from the N3 domain. * Zonal drift profiles Previous spacecraft ZWPs have revealed the overall pattern of the domains: in both N4 and N5, the ZWP is ‘blunt’ with a broad retrograde flow (Figure 1). The Cassini polar movie, and our long-term ground-based analysis [ref.2], suggested that this represents the bulk motion of the rapidly-changing FFRs, and this is confirmed by tracking features in 2021. The mean speeds in L3 are: in N4, +14 deg/30d; in N5, +20 deg/30d. Faster retrograde winds exist in the FFRs. Conversely, AWOs have fast prograding drifts when in the northern part of each domain, but steady retrograding drifts in the southern part, where they often wander in latitude (especially in N4). The largest AWO, in N5, has probably been tracked for at least 3 years and often progrades with the N6 jet. Some smaller AWOs are also long-lived, while others appear and disappear within months. * Influences on the zonal drifts In both N4 and N5, AWOs often undergo sudden large changes in their latitude and drift rate (Figure 3) – just as in the N2, S3 & S4 domains. Decelerations are sometimes due to the AWO encountering a FFR, according to examples in the Cassini polar movie and long-term ground-based analysis combined with Hubble maps [ref.2]. Accelerations may sometimes be due to the AWO encountering a smaller white spot. AWOs sometimes pass each other in different latitudes unperturbed, but sometimes their mutual interactions can lead to mergers, or cause one or both to change latitude and speed. In 2021, a pair in N5 rebounded exchang-ing tracks, and other interactions may have propelled a N4 and a N3 AWO southwards to cross the jet. * AWOs crossing prograde jets Coherent circulations almost never cross prograde jets on Jupiter, but ground-based data has demonstrated two previous instances where a N4 AWO crossed the N4 jet into the N3 domain, and in 2021-22 there was probably a third such event, captured in JunoCam images. N4-AWO-A swung rapidly southwards after it approached N4-AWO-B (Figures 3 & 4), and was last seen at PJ39, straddling the N4 jet and split into two lobes (Figure 4). Likewise, a N3-AWO swung southwards and crossed the N3 jet into the NNTZ – the first time that a spot has been seen to cross a prograde jet other than the N4 jet. * Cloud textures JunoCam provides unprecedented resolution on the cloud-tops in this region, revealing features such as ‘pop-up clouds’; these are small, very bright white clouds only ten(s) of km across, projecting above the main cloud deck [ref.3], seen in many locations including AWOs, FFRs, and linear white cloud bands outside the main circulations (Figure 5). AWOs have thick white cloud cover with spiral streaking and scattered pop-up clouds. There are also much smaller vortices, both anticyclonic and cyclonic; the latter include well-formed orange-brown spiral cyclones, and ovals with quiescent dark brown cloud-covered interiors. FFRs have a variety of white, grey and orange clouds and hazes that appear to be at different levels. Dense rows of pop-up clouds are commonly seen on the white strips in FFRs, possibly representing the uppermost layer of convection. These white strips are probably thunderstorms, as FFRs in N4 are the most frequent location on the planet for lightning strikes [ref.4]. Acknowledgements: Some of this research was funded by NASA. A portion of this was distributed to the Jet Propulsion Laboratory, California Institute of Technology. References: 1. Simon AA, Wong MH & Orton GS, NASA & ESA: OPAL project: https://archive.stsci.edu/prepds/opal/. See this website for maps and credits. 2. Rogers J et al., (2017), ‘Jupiter’s high northern latitudes: patterns and dynamics of the N3 to N6 domains.’ https://britastro.org/node/11328 3. Hansen C et al. (2019), ‘JunoCam images of castellanus clouds on Jupiter.’ AGU abstract #P44A-05. 4. Brown S et al.(2018), ‘Prevalent lightning sferics at 600 MHz near Jupiter’s poles.’ Nature 558, 87-90.

A complex series of high-altitude clouds and hazes have been unveiled by images from the Juno mission’s JunoCam instrument. They appear to be ubiquitous at higher latitudes in both of Jupiter’s hemispheres but are particularly pronounced in the north. Juno’s polar orbit and JunoCam’s filter centered on the 889-nm absorption band of methane make JunoCam uniquely suited to observing high-altitude polar features. Among these are the North and South Polar Hoods, which JunoCam’s methane-band filter reveals in greater detail than from the Earth, together with bright and dark haze bands. These bright and dark bands commonly appear together in bundles, indicating vertical structure in widespread haze layers. Some bright hazes near the terminator exhibit an apparent color dispersion, appearing bluish on the side generally in the direction of illumination and reddish on the other, an effect that is consistent with more efficient scattering by shorter-wavelength light. The morphology of the observed haze bands appears to be quite different from the well-known zonal wind profile affecting the main cloud deck. On the other hand, some, including a semi-persistent long band of haze near the South Pole, are related to the locations of underlying cyclones and chaotic cyclonic features known as folded filamentary regions. Our high-resolution observations of Jupiter’s limb have revealed hazes, some continuous with the lower atmosphere and others that are singly and doubly detached. Toward high northern latitudes, these limb hazes become completely opaque.

Jupiter’s cyclonic features are known to undergo transitions between quiescent states with smooth edges (often appearing as dark brown ‘barges’) to states with convective outbursts of billowing white clouds, chaotically churned into filamentary structures. Cyclones in the latter state are known as ‘Folded Filamentary Regions’ (FFRs), and Voyager images (Ingersoll+1979, doi: 10.1038/280773a0) revealed them to be rapidly-varying turbulent regions, occurring in cyclonic domains on the poleward side of Jupiter’s prograde jets. JunoCam visible-light observations (Orton+2017, doi:10.1002/2016GL072443, Rogers+2021, doi:10.1016/j.icarus.2021.114742), reveal the increasing prevalence of FFRs at mid-to-high latitudes. They dominate the polar domain alongside smaller anticyclonic white ovals, drifting westward in latitude bands between the narrow prograde jets, and rapidly evolving over timescales of days. The present study makes use of Juno’s ever-improving microwave observations of the north polar domain, as the latitude of closest-approach (“perijove”) moves northward. We therefore focus on FFRs in the northern hemisphere, where we find them to occur in zonally-organised latitude bands even at high latitudes. Statistics of the FFRs suggest that they occur on the poleward sides of the N4 (43.3oN, centric), N5 (52.3oN), and N7 (66.1oN) prograde jets (N6 at 61.2oN coincides with a ‘bland zone’ lacking notable FFRs), and scattered in the polar domain up to the octagon of circumpolar cyclones at 85oN. JIRAM 5-µm imaging of both poles reveal FFRs as generally dark structures with elevated aerosol opacity blocking thermal infrared emission from the 4-6 bar level, coinciding with the white stratiform clouds observed by JunoCam. Clusters of small cumulus-like clouds, as well as curvilinear cloud streaks, provide texture to the flat stratiform clouds to give the appearance of a network of filaments. Visibly-dark lanes border the brighter filaments, creating an intricate network of narrow, aerosol-free, and 5-µm-bright striations within each FFR. This is in contrast to cyclonic features such as barges at lower latitudes, where an absence of overlying aerosols generally renders them 5-µm bright. A survey of 1.4-50 cm observations acquired by Juno’s Microwave Radiometer (MWR) between PJ20 (May 2019) to PJ37 (October 2021) reveals that FFRs share a key characteristic with their low-latitude counterparts: they are microwave-bright in channels sounding the 0.6-2.0 bar range (1.4-3.0 cm), become hard to distinguish from their surroundings near 5 bars (5.75 cm), but are then microwave-dark in the channel sounding 10-15 bar (11.5 cm). This suggests FFRs are depleted in ammonia gas and/or locally warmer at levels above the putative location of Jupiter’s water cloud, the latter implying a decay of cyclonic winds with altitude. This shallow ammonia depletion is surprising, given the apparent convective nature of the FFRs - maybe NH3-rich plumes occupy a sufficiently small area of the cyclonic structure, so that they have negligible impact on the warm emission observed by MWR. This shallow depletion is balanced by a local NH3 enrichment (or local cooling) at depth, below the water cloud, like a cyclonic lens. However, the extension of FFR signatures to deeper levels (p>20 bars) is currently unclear due to insufficient spatial coverage and resolution at the longest-wave channels, and confusion arising from auroral contributions to the MWR dataset at 50 cm. An inversion in microwave brightness with depth was previously identified for Jupiter’s larger-scale belts and zones (Fletcher+2021, doi:10.1029/2021JE006858) and mid-latitude discrete features (Bolton+2021, doi:10.1126/science.abf1015), and now appears to be common at high latitudes as well. Geostrophy implies that cyclonic circulations (low-pressure centers) cause a rise in potential-temperature surfaces in deeper layers, potentially triggering moist convection in the water cloud (e.g., Dowling & Gierasch, 1989 Bull. Amer. Astron. Soc 21, 946; Fletcher+2017, doi:10.1016/j.icarus.2017.01.001), producing the distinct convective cloud structure observed by visible and infrared imaging: juxtaposed tall convective towers, deep water clouds, and narrow clear lanes (Imai+2020, doi:10.1029/2020GL088397). Lightning sferics measured by MWR at 50 cm/600 MHz are more frequent in the N4, N5, and N7 domains where FFRs are common (Brown+2018, doi:10.1038/s41586-018-0156-5), and are further clustered in FFRs themselves (Wong+2020, doi:10.3847/1538-4365/ab775f). Thus the evolution of the cyclonic FFRs, and their penetration to the moist depths below the water condensation level, may hold the key to understanding the distribution of lightning activity on Jupiter.

Previous studies of Jupiter's wind patterns revealed the southernmost two prograde jets at 58 degrees S and 64 degrees S (planetocentric), which we designate as the S5 and S6 jets, respectively, but the jets and the wind patterns further poleward were not well defined. The Juno mission has provided the first opportunity to study the South Polar Region (SPR). Here we use images from Juno's camera, JunoCam, to characterize these jets and the wind patterns further south. We measure the main wind systems using JunoCam images taken up to two hours apart. The S5 jet coincides with a slightly sinuous boundary in methane-band images. The S6 jet is faster, broader and highly undulating in latitude, generally coinciding with the sinuous edge of the methane-bright South Polar Hood, whose wave pattern is often regular with a mean wavelength of 25.5 degrees (+/- 2.6 degrees) longitude. Peak wind speeds along the S6 jet range from 42 (+/- 12) to 49 (+/- 11) m/s, faster than previously recognized. Poleward of the S6 jet, at similar to 65-70 degrees S, there is an irregular belt of chaotic cyclonic regions termed folded filamentary regions (FFRs), with several small anticyclonic white ovals (AWOs) on or near its southern edge. Some of these FFRs appear to be extending northeast into the S6 jet. More FFRs are scattered from similar to 70 to 80 degrees S. Wind speeds in the FFRs are generally similar to 20-60 m/s, comparable to lower-latitude cyclonic circulations. We also generate semi-quantitative maps of local vorticity, and thence, mean zonal vorticity profiles as a function of latitude. These confirm the S6 jet as sinuous and the southernmost belt of FFRs as a stable belt. Further south, there is usually a weak cyclonic vorticity maximum near 78 degrees S, which probably represents irregular structures such as FFRs. Supplementary ground-based images, spaced by up to 4 days, show westward drifts for the similar to 65-70 degrees S belt, with a mean of similar to + 0.9 degrees/day in System III longitude. AWOs can also be tracked, for months or even years. They drift westward with a uniform speed of +0.8 degrees/day between 69.5 and 72.4 degrees S, but towards higher latitudes, up to 76 degrees S, they show a steep latitudinal gradient to faster (eastward) speeds, comparable to those measured around the south polar pentagon of circumpolar cyclones at similar to 80 degrees S. Overall, the similar to 65-70 degrees S belt and associated AWOs show dynamical behaviour similar to lower latitudes. Further south, there are no rapid continuous jets, but the loose enhancement of cyclonic structures near 78 degrees S suggests a trace of zonal structure extending almost as far as the polar pentagon.