bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of MeV electrons in Jupiter's innermost radiation belts and polar regions by the Juno radiation monitoring investigation: Perijoves 1 and 3
Authors: Becker Heidi N. , Santos‐Costa Daniel , Jørgensen John L. , Denver Troelz , Adriani Alberto , Mura Alessandro , Connerney John E. P. , Bolton Scott J. , Levin Steven M. , Thorne Richard M. , Alexander James W. , Adumitroaie Virgil , Manor‐Chapman Emily A. , Daubar Ingrid J. , Lee Clifford , Benn Mathias , Sushkova Julia , Cicchetti Andrea , Noschese Raffaella 
Published: May 2017

AbstractJuno's “Perijove 1” (27 August 2016) and “Perijove 3” (11 December 2016) flybys through the innermost region of Jupiter's magnetosphere (radial distances <2 Jovian radii, 1.06 RJ at closest approach) provided the first in situ look at this region's radiation environment. Juno's Radiation Monitoring Investigation collected particle counts and noise signatures from penetrating high‐energy particle impacts in images acquired by the Stellar Reference Unit and Advanced Stellar Compass star trackers, and the Jupiter Infrared Auroral Mapper infrared imager. This coordinated observation campaign sampled radiation at the inner edges of the high‐latitude lobes of the synchrotron emission region and more distant environments. Inferred omnidirectional >5 MeV and >10 MeV electron fluxes derived from these measurements provide valuable constraints for models of relativistic electron environments in the inner radiation belts. Several intense bursts of high‐energy particle counts were also observed by the Advanced Stellar Compass in polar regions outside the radiation belts.
Morphology of the UV aurorae Jupiter during Juno's first perijove observations
Authors: Bonfond B. , Gladstone G. R. , Grodent D. , Greathouse T. K. , Versteeg M. H. , Hue V. , Davis M. W. , Vogt M. F. , Gérard J.‐C. , Radioti A. , Bolton S. , Levin S. M. , Connerney J. E. P. , Mauk B. H. , Valek P. , Adriani A. , Kurth W. S. 
Published: May 2017

AbstractOn 27 August 2016, the NASA Juno spacecraft performed its first close‐up observations of Jupiter during its perijove. Here we present the UV images and color ratio maps from the Juno‐UVS UV imaging spectrograph acquired at that time. Data were acquired during four sequences (three in the north, one in the south) from 5:00 UT to 13:00 UT. From these observations, we produced complete maps of the Jovian aurorae, including the nightside. The sequence shows the development of intense outer emission outside the main oval, first in a localized region (255°–295° System III longitude) and then all around the pole, followed by a large nightside protrusion of auroral emissions from the main emission into the polar region. Some localized features show signs of differential drift with energy, typical of plasma injections in the middle magnetosphere. Finally, the color‐ratio map in the north shows a well‐defined area in the polar region possibly linked to the polar cap.
Variability of Jupiter's IR H3+ aurorae during Juno approach
Authors: Moore L. , O'Donoghue J. , Melin H. , Stallard T. , Tao C. , Zieger B. , Clarke J. , Vogt M. F. , Bhakyapaibul T. , Opher M. , Tóth G. , Connerney J. E. P. , Levin S. , Bolton S. 
Published: May 2017

AbstractWe present ground‐based observations of Jupiter's H3+ aurorae over four nights in April 2016 while the Juno spacecraft was monitoring the upstream interplanetary magnetic field. High‐precision maps of auroral H3+ densities, temperatures, and radiances reveal significant variabilities in those parameters, with regions of enhanced density and emission accompanied by reduced temperature. Juno magnetometer data, combined with solar wind propagation models, suggest that a shock may have impacted Jupiter in the days preceding the observation interval but that the solar wind was quiescent thereafter. Auroral H3+ temperatures reveal a downward temporal trend, consistent with a slowly cooling upper atmosphere, such as might follow a period of shock recovery. The brightest H3+ emissions are from the end of the period, 23 April. A lack of definitive signatures in the upstream interplanetary magnetic field lends supporting evidence to the possibility that this brightening event may have been driven by internal magnetospheric processes.
The distribution of ammonia on Jupiter from a preliminary inversion of Juno microwave radiometer data
Authors: Li Cheng , Ingersoll Andrew , Janssen Michael , Levin Steven , Bolton Scott , Adumitroaie Virgil , Allison Michael , Arballo John , Bellotti Amadeo , Brown Shannon , Ewald Shawn , Jewell Laura , Misra Sidharth , Orton Glenn , Oyafuso Fabiano , Steffes Paul , Williamson Ross 
Published: May 2017

AbstractThe Juno microwave radiometer measured the thermal emission from Jupiter's atmosphere from the cloud tops at about 1 bar to as deep as a hundred bars of pressure during its first flyby over Jupiter (PJ1). The nadir brightness temperatures show that the Equatorial Zone is likely to be an ideal adiabat, which allows a determination of the deep ammonia abundance in the range
ppm. The combination of Markov chain Monte Carlo method and Tikhonov regularization is studied to invert Jupiter's global ammonia distribution assuming a prescribed temperature profile. The result shows (1) that ammonia is depleted globally down to 50–60 bars except within a few degrees of the equator, (2) the North Equatorial Belt is more depleted in ammonia than elsewhere, and (3) the ammonia concentration shows a slight inversion starting from about 7 bars to 2 bars. These results are robust regardless of the choice of water abundance.
Hot flow anomaly observed at Jupiter's bow shock
Authors: Valek P. W. , Thomsen M. F. , Allegrini F. , Bagenal F. , Bolton S. , Connerney J. , Ebert R. W. , Gladstone R. , Kurth W. S. , Levin S. , Louarn P. , Mauk B. , McComas D. J. , Pollock C. , Reno M. , Szalay J. R. , Weidner S. , Wilson R. J. 
Published: May 2017

AbstractA Hot Flow Anomaly (HFA) is created when an interplanetary current sheet interacts with a planetary bow shock. Previous studies have reported observing HFAs at Earth, Mercury, Venus, Mars, and Saturn. During Juno's approach to Jupiter, a number of its instruments operated in the solar wind. Prior to crossing into Jupiter's magnetosphere, Juno observed an HFA at Jupiter for the first time. This Jovian HFA shares most of the characteristics of HFAs seen at other planets. The notable exception is that the Jovian HFA is significantly larger than any HFA seen before. With an apparent size greater than 2 × 106 km the Jovian HFA is orders of magnitude larger than those seen at the other planets. By comparing the size of the HFAs at the other planets with the Jovian HFA, we conclude that HFAs size scales with the size of planetary bow shocks that the interplanetary current sheet interacts with.
Jovian bow shock and magnetopause encounters by the Juno spacecraft
Authors: Hospodarsky G. B. , Kurth W. S. , Bolton S. J. , Allegrini F. , Clark G. B. , Connerney J. E. P. , Ebert R. W. , Haggerty D. K. , Levin S. , McComas D. J. , Paranicas C. , Rymer A. M. , Valek P. W. 
Published: May 2017

AbstractThe Juno spacecraft has crossed Jupiter's bow shock (BS) and magnetopause (MP) multiple times in the dawn sector (near 0600 local time), both during the approach to Jupiter and during the first three apojove periods. A survey of all of these crossings using the Juno field and particle instruments has been performed, with 51 bow shock and 97 magnetopause crossings being detected. The BS crossings ranged from 92 to 128 RJ with 1 encounter during the approach, 36 during the first apojove period, 0 on the second, and 14 during the third. The MP crossings ranged from 73 to 114 RJ, with 8 MP encounters during the approach, 40 encounters during the first apojove period, 24 encounters on the second, and 46 during the third. During the approach, Juno initially encountered an expanding magnetosphere resulting in a single BS and MP crossing, followed a few days later by a contracting magnetosphere, resulting in 7 more MP crossings and a BS crossing on the first outbound orbit at 92 RJ. The lack of BS crossings and the limited number of MP crossings during the second apojove period suggests a long period of an expanded magnetosphere, likely caused by a prolonged period of low solar wind dynamic pressure associated with a rarefaction region. The detection of BS crossings on the third apojove period suggests another period of a highly compressed magnetosphere.
Electron beams and loss cones in the auroral regions of Jupiter
Authors: Allegrini F. , Bagenal F. , Bolton S. , Connerney J. , Clark G. , Ebert R. W. , Kim T. K. , Kurth W. S. , Levin S. , Louarn P. , Mauk B. , McComas D. J. , Pollock C. , Ranquist D. , Reno M. , Szalay J. R. , Thomsen M. F. , Valek P. , Weidner S. , Wilson R. J. , Zink J. L. 
Published: May 2017

AbstractWe report on the first observations of 100 eV to 100 keV electrons over the auroral regions of Jupiter by the Jovian Auroral Distributions Experiment (JADE) on board the Juno mission. The focus is on the regions that were magnetically connected to the main auroral oval. Amongst the most remarkable features, JADE observed electron beams, mostly upward going but also some downward going in the south, at latitudes from ~69° to 72° and ~ −66° to −70° corresponding to M shells (“M” for magnetic) from ~18 to 54 and ~28 to 61, respectively. The beams were replaced by upward loss cones at lower latitudes. There was no evidence of strongly accelerated downward electrons analogous to the auroral “inverted Vs” at Earth. Rather, the presence of upward loss cones suggests a diffuse aurora process. The energy spectra resemble tails of distributions or power laws (suggestive of a stochastic acceleration process) but can also have some clear enhancements or even peaks generally between 1 and 10 keV. Electron intensities change on timescales of a second or less at times implying that auroral structures can be of the order of a few tens of kilometers.
Observations of interplanetary dust by the Juno magnetometer investigation
Authors: Benn M. , Jorgensen J. L. , Denver T. , Brauer P. , Jorgensen P. S. , Andersen A. C. , Connerney J. E. P. , Oliversen R. , Bolton S. J. , Levin S. 
Published: May 2017

AbstractOne of the Juno magnetometer investigation's star cameras was configured to search for unidentified objects during Juno's transit en route to Jupiter. This camera detects and registers luminous objects to magnitude 8. Objects persisting in more than five consecutive images and moving with an apparent angular rate of between 2 and 18,000 arcsec/s were recorded. Among the objects detected were a small group of objects tracked briefly in close proximity to the spacecraft. The trajectory of these objects demonstrates that they originated on the Juno spacecraft, evidently excavated by micrometeoroid impacts on the solar arrays. The majority of detections occurred just prior to and shortly after Juno's transit of the asteroid belt. This rather novel detection technique utilizes the Juno spacecraft's prodigious 60 m2 of solar array as a dust detector and provides valuable information on the distribution and motion of interplanetary (>μm sized) dust.
Juno‐UVS approach observations of Jupiter's auroras
Authors: Gladstone G. R. , Versteeg M. H. , Greathouse T. K. , Hue V. , Davis M. W. , Gérard J.‐C. , Grodent D. C. , Bonfond B. , Nichols J. D. , Wilson R. J. , Hospodarsky G. B. , Bolton S. J. , Levin S. M. , Connerney J. E. P. , Adriani A. , Kurth W. S. , Mauk B. H. , Valek P. , McComas D. J. , Orton G. S. , Bagenal F. 
Published: May 2017

AbstractJuno ultraviolet spectrograph (UVS) observations of Jupiter's aurora obtained during approach are presented. Prior to the bow shock crossing on 24 June 2016, the Juno approach provided a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions are expected to be controlled or modified by local solar wind conditions. Here we compare synoptic Juno‐UVS observations of Jupiter's auroral emissions, acquired during 3–29 June 2016, with in situ solar wind observations, and related Jupiter observations from Earth. Four large auroral brightening events are evident in the synoptic data, in which the total emitted auroral power increases by a factor of 3–4 for a few hours. Only one of these brightening events correlates well with large transient increases in solar wind ram pressure. The brightening events which are not associated with the solar wind generally have a risetime of ~2 h and a decay time of ~5 h.
Jupiter's North Equatorial Belt expansion and thermal wave activity ahead of Juno's arrival
Authors: Fletcher L. N. , Orton G. S. , Sinclair J. A. , Donnelly P. , Melin H. , Rogers J. H. , Greathouse T. K. , Kasaba Y. , Fujiyoshi T. , Sato T. M. , Fernandes J. , Irwin P. G. J. , Giles R. S. , Simon A. A. , Wong M. H. , Vedovato M. 
Published: May 2017

AbstractThe dark colors of Jupiter's North Equatorial Belt (NEB, 7–17°N) appeared to expand northward into the neighboring zone in 2015, consistent with a 3–5 year cycle. Inversions of thermal‐IR imaging from the Very Large Telescope revealed a moderate warming and reduction of aerosol opacity at the cloud tops at 17–20°N, suggesting subsidence and drying in the expanded sector. Two new thermal waves were identified during this period: (i) an upper tropospheric thermal wave (wave number 16–17, amplitude 2.5 K at 170 mbar) in the mid‐NEB that was anticorrelated with haze reflectivity; and (ii) a stratospheric wave (wave number 13–14, amplitude 7.3 K at 5 mbar) at 20–30°N. Both were quasi‐stationary, confined to regions of eastward zonal flow, and are morphologically similar to waves observed during previous expansion events.
Jupiter cloud morphology and zonal winds from ground‐based observations before and during Juno's first perijove
Authors: Hueso R. , Sánchez‐Lavega A. , Iñurrigarro P. , Rojas J. F. , Pérez‐Hoyos S. , Mendikoa I. , Gómez‐Forrellad J. M. , Go C. , Peach D. , Colas F. , Vedovato M. 
Published: May 2017

AbstractWe analyze Jupiter observations between December 2015 and August 2016 in the 0.38–1.7 μm wavelength range from the PlanetCam instrument at the 2.2 m telescope at Calar Alto Observatory and in the optical range by amateur observers contributing to the Planetary Virtual Observatory Laboratory. Over this time Jupiter was in a quiescent state without notable disturbances. Analysis of ground‐based images and Hubble Space Telescope observations in February 2016 allowed the retrieval of mean zonal winds from −74.5° to +73.2°. These winds did not change over 2016 or when compared with winds from previous years with the sole exception of intense zonal winds at the North Temperate Belt. We also present results concerning the major wave systems in the North Equatorial Belt and in the upper polar hazes visible in methane absorption bands, a description of the planet's overall cloud morphology and observations of Jupiter hours before Juno's orbit insertion.
The effect of differential rotation on Jupiter's low‐degree even gravity moments
Authors: Kaspi Y. , Guillot T. , Galanti E. , Miguel Y. , Helled R. , Hubbard W. B. , Militzer B. , Wahl S. M. , Levin S. , Connerney J. E. P. , Bolton S. J. 
Published: May 2017

AbstractThe close‐by orbits of the ongoing Juno mission allow measuring with unprecedented accuracy Jupiter's low‐degree even gravity moments J2, J4, J6, and J8. These can be used to better determine Jupiter's internal density profile and constrain its core mass. Yet the largest unknown on these gravity moments comes from the effect of differential rotation, which gives a degree of freedom unaccounted for by internal structure models. Here considering a wide range of possible internal flow structures and dynamical considerations, we provide upper bounds to the effect of dynamics (differential rotation) on the low‐degree gravity moments. In light of the recent Juno gravity measurements and their small uncertainties, this allows differentiating between the various models suggested for Jupiter's internal structure.
A heavy ion and proton radiation belt inside of Jupiter's rings
Authors: Kollmann P. , Paranicas C. , Clark G. , Mauk B. H. , Haggerty D. K. , Rymer A. M. , Santos‐Costa D. , Connerney J. E. P. , Allegrini F. , Valek P. , Kurth W. S. , Gladstone G. R. , Levin S. , Bolton S. 
Published: May 2017

AbstractEnergetic charged particle measurements by the Jupiter Energetic Particle Detector Instrument (JEDI) on board Juno have revealed a radiation belt of hundreds of keV ions up to the atomic mass of sulfur, located between Jupiter's rings and atmosphere. Proton energy spectra display an unusual intensity increase above 300 keV. We suggest that this is because charge exchange in Jupiter's neutral environment does not efficiently remove ions at such high energies. Since this innermost belt includes heavy ions, it cannot be exclusively supplied by cosmic ray albedo neutron decay, which is an important source at Earth and Saturn but only supplies protons and electrons. We find indications that the stripping of energetic neutral atoms in Jupiter's high atmosphere might be the ion source. Since the stripped off electrons are of low energy, this hypothesis is consistent with observations of the ratio of energetic electrons to ions being much less than 1.
Cycles of activity in the Jovian atmosphere
Authors: Fletcher L. N. 
Published: May 2017

AbstractJupiter's banded appearance may appear unchanging to the casual observer, but closer inspection reveals a dynamic, ever‐changing system of belts and zones with distinct cycles of activity. Identification of these long‐term cycles requires access to data sets spanning multiple Jovian years, but explaining them requires multispectral characterization of the thermal, chemical, and aerosol changes associated with visible color variations. The Earth‐based support campaign for Juno's exploration of Jupiter has already characterized two upheaval events in the equatorial and temperate belts that are part of long‐term Jovian cycles, whose underlying sources could be revealed by Juno's exploration of Jupiter's deep atmosphere.
A close‐up view of Jupiter's magnetic field from Juno: New insights into the planet's deep interior
Authors: Jones Chris A. , Holme Richard 
Published: May 2017

AbstractThe first results from the Juno mission magnetometer have recently become available. Juno provides us with the closest view of any planetary dynamo, flying to within 1.25 of the radius of the dynamo region, whereas for the Earth, we cannot get closer than 1.83 of the core‐mantle boundary radius. We compare the Juno results with those from first principles dynamo simulations of Jupiter's magnetic field. Intense flux patches at Jupiter's surface are found in both the data and the simulations, though the simulations have them mainly at slightly higher latitudes than the observations. We consider the prospects for determining more accurately the location of the top of the metallic hydrogen region and the implications of possible weak flux patches at the poles.
The soil moisture velocity equation
Authors: Ogden Fred L. , Allen Myron B. , Lai Wencong , Zhu Jianting , Seo Mookwon , Douglas Craig C. , Talbot Cary A. 
Published: May 2017

AbstractNumerical solution of the one‐dimensional Richards' equation is the recommended method for coupling groundwater to the atmosphere through the vadose zone in hyperresolution Earth system models, but requires fine spatial discretization, is computationally expensive, and may not converge due to mathematical degeneracy or when sharp wetting fronts occur. We transformed the one‐dimensional Richards' equation into a new equation that describes the velocity of moisture content values in an unsaturated soil under the actions of capillarity and gravity. We call this new equation the Soil Moisture Velocity Equation (SMVE). The SMVE consists of two terms: an advection‐like term that accounts for gravity and the integrated capillary drive of the wetting front, and a diffusion‐like term that describes the flux due to the shape of the wetting front capillarity profile divided by the vertical gradient of the capillary pressure head. The SMVE advection‐like term can be converted to a relatively easy to solve ordinary differential equation (ODE) using the method of lines and solved using a finite moisture‐content discretization. Comparing against analytical solutions of Richards' equation shows that the SMVE advection‐like term is >99% accurate for calculating infiltration fluxes neglecting the diffusion‐like term. The ODE solution of the SMVE advection‐like term is accurate, computationally efficient and reliable for calculating one‐dimensional vadose zone fluxes in Earth system and large‐scale coupled models of land‐atmosphere interaction. It is also well suited for use in inverse problems such as when repeat remote sensing observations are used to infer soil hydraulic properties or soil moisture.
Trade‐off between cost and accuracy in large‐scale surface water dynamic modeling
Authors: Getirana Augusto , Peters‐Lidard Christa , Rodell Matthew , Bates Paul D. 
Published: May 2017

AbstractRecent efforts have led to the development of the local inertia formulation (INER) for an accurate but still cost‐efficient representation of surface water dynamics, compared to the widely used kinematic wave equation (KINE). In this study, both formulations are evaluated over the Amazon basin in terms of computational costs and accuracy in simulating streamflows and water levels through synthetic experiments and comparisons against ground‐based observations. Varying time steps are considered as part of the evaluation and INER at 60 s time step is adopted as the reference for synthetic experiments. Five hybrid (HYBR) realizations are performed based on maps representing the spatial distribution of the two formulations that physically represent river reach flow dynamics within the domain. Maps have fractions of KINE varying from 35.6 to 82.8%. KINE runs show clear deterioration along the Amazon river and main tributaries, with maximum RMSE values for streamflow and water level reaching 7827 m3 s−1 and 1379 cm near the basin's outlet. However, KINE is at least 25% more efficient than INER with low model sensitivity to longer time steps. A significant improvement is achieved with HYBR, resulting in maximum RMSE values of 3.9–292 m3 s−1 for streamflows and 1.1–28.5 cm for water levels, and cost reduction of 6–16%, depending on the map used. Optimal results using HYBR are obtained when the local inertia formulation is used in about one third of the Amazon basin, reducing computational costs in simulations while preserving accuracy. However, that threshold may vary when applied to different regions, according to their hydrodynamics and geomorphological characteristics.
Analytical estimation show low depth‐independent water loss due to vapor flux from deep aquifers
Authors: Selker John S. 
Published: May 2017

AbstractRecent articles have provided estimates of evaporative flux from water tables in deserts that span 5 orders of magnitude. In this paper, we present an analytical calculation that indicates aquifer vapor flux to be limited to 0.01 mm/yr for sites where there is negligible recharge and the water table is well over 20 m below the surface. This value arises from the geothermal gradient, and therefore, is nearly independent of the actual depth of the aquifer. The value is in agreement with several numerical studies, but is 500 times lower than recently reported experimental values, and 100 times larger than an earlier analytical estimate.