Author
Eli Galanti
Other affiliations: Tel Aviv University
Bio: Eli Galanti is an academic researcher from Weizmann Institute of Science. The author has contributed to research in topics: Jupiter & Gravitational field. The author has an hindex of 23, co-authored 65 publications receiving 1703 citations. Previous affiliations of Eli Galanti include Tel Aviv University.
Topics: Jupiter, Gravitational field, Planet, Gravity (chemistry), Saturn
Papers published on a yearly basis
Papers
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University of California, Berkeley1, University of Arizona2, University of Nice Sophia Antipolis3, Tel Aviv University4, University of California, Santa Cruz5, Weizmann Institute of Science6, University of Zurich7, Paris Diderot University8, Goddard Space Flight Center9, Southwest Research Institute10
TL;DR: In this paper, a selection of interior models based on ab initio computer simulations of hydrogen-helium mixtures is presented. But, the model predictions are strongly affected by the chosen equation of state, the prediction of an enrichment of Z in the deep, metallic envelope over that in the shallow, molecular envelope holds.
Abstract: The Juno spacecraft has measured Jupiter's low-order, even gravitational moments, J2–J8, to an unprecedented precision, providing important constraints on the density profile and core mass of the planet. Here we report on a selection of interior models based on ab initio computer simulations of hydrogen-helium mixtures. We demonstrate that a dilute core, expanded to a significant fraction of the planet's radius, is helpful in reconciling the calculated Jn with Juno's observations. Although model predictions are strongly affected by the chosen equation of state, the prediction of an enrichment of Z in the deep, metallic envelope over that in the shallow, molecular envelope holds. We estimate Jupiter's core to contain a 7–25 Earth mass of heavy elements. We discuss the current difficulties in reconciling measured Jn with the equations of state and with theory for formation and evolution of the planet.
279 citations
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Weizmann Institute of Science1, University of Arizona2, California Institute of Technology3, Southwest Research Institute4, Sapienza University of Rome5, Centre national de la recherche scientifique6, Harvard University7, Goddard Space Flight Center8, University of Zurich9, Cornell University10, Leiden University11, University of California, Berkeley12
TL;DR: It is reported that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000 kilometres.
Abstract: The depth to which Jupiter’s observed east–west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno’s gravitational measurements have revealed that Jupiter’s gravitational field is north–south asymmetric, which is a signature of the planet’s atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J_3, J_5, J_7 and J_9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000 kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J_8 and J_(10) resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter’s total mass.
232 citations
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Centre national de la recherche scientifique1, Leiden University2, University of California, Berkeley3, University of Arizona4, Weizmann Institute of Science5, California Institute of Technology6, Harvard University7, University of Zurich8, Sapienza University of Rome9, Cornell University10, Paris Diderot University11, Goddard Space Flight Center12, Southwest Research Institute13
TL;DR: It is found that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics.
Abstract: Jupiter’s atmosphere is rotating differentially, with zones and belts rotating at speeds that differ by up to 100 metres per second. Whether this is also true of the gas giant’s interior has been unknown, limiting our ability to probe the structure and composition of the planet. The discovery by the Juno spacecraft that Jupiter’s gravity field is north–south asymmetric and the determination of its non-zero odd gravitational harmonics J_3, J_5, J_7 and J_9 demonstrates that the observed zonal cloud flow must persist to a depth of about 3,000 kilometres from the cloud tops. Here we report an analysis of Jupiter’s even gravitational harmonics J_4, J_6, J_8 and J_(10) as observed by Juno and compared to the predictions of interior models. We find that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. Moreover, we find that the atmospheric zonal flow extends to more than 2,000 kilometres and to less than 3,500 kilometres, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics. This depth corresponds to the point at which the electric conductivity becomes large and magnetic drag should suppress differential rotation. Given that electric conductivity is dependent on planetary mass, we expect the outer, differentially rotating region to be at least three times deeper in Saturn and to be shallower in massive giant planets and brown dwarfs.
183 citations
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TL;DR: The results show that Saturn's rings are substantially younger than the planet itself and constrain models of their origin, and five small moons located in and around the rings are presented, confirming that the flows are very deep and likely extend down to the levels where magneticipation occurs.
Abstract: The interior structure of Saturn, the depth of its winds, and the mass and age of its rings constrain its formation and evolution. In the final phase of the Cassini mission, the spacecraft dived between the planet and its innermost ring, at altitudes of 2600 to 3900 kilometers above the cloud tops. During six of these crossings, a radio link with Earth was monitored to determine the gravitational field of the planet and the mass of its rings. We find that Saturn's gravity deviates from theoretical expectations and requires differential rotation of the atmosphere extending to a depth of at least 9000 kilometers. The total mass of the rings is (1.54 ± 0.49) × 1019 kilograms (0.41 ± 0.13 times that of the moon Mimas), indicating that the rings may have formed 107 to 108 years ago.
177 citations
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Sapienza University of Rome1, California Institute of Technology2, Weizmann Institute of Science3, University of Arizona4, Southwest Research Institute5, University of Bologna6, University of Pisa7, University of Zurich8, Cornell University9, University of California, Berkeley10, Goddard Space Flight Center11
TL;DR: Measurements of Jupiter’s gravity harmonics are reported through precise Doppler tracking of the Juno spacecraft in its polar orbit around Jupiter, finding a north–south asymmetry, which is a signature of atmospheric and interior flows.
Abstract: The gravity harmonics of a fluid, rotating planet can be decomposed into static components arising from solid-body rotation and dynamic components arising from flows. In the absence of internal dynamics, the gravity field is axially and hemispherically symmetric and is dominated by even zonal gravity harmonics J_(2n) that are approximately proportional to q^n, where q is the ratio between centrifugal acceleration and gravity at the planet’s equator. Any asymmetry in the gravity field is attributed to differential rotation and deep atmospheric flows. The odd harmonics, J_3, J_5, J_7, J_9 and higher, are a measure of the depth of the winds in the different zones of the atmosphere. Here we report measurements of Jupiter’s gravity harmonics (both even and odd) through precise Doppler tracking of the Juno spacecraft in its polar orbit around Jupiter. We find a north–south asymmetry, which is a signature of atmospheric and interior flows. Analysis of the harmonics, described in two accompanying papers, provides the vertical profile of the winds and precise constraints for the depth of Jupiter’s dynamical atmosphere.
171 citations
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01 Jan 1989
TL;DR: In this article, a two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea.
Abstract: Abstract A two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea. The domain includes a representation of part of Borneo as well as the sea so that the model can simulate the initiation of convection. Also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle. This allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck, which typically occupies several hundred kilometers of the domain. Frank and Cohen's cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area. The major conclusions are: Ice phase processes are important in determining the level of maximum large-scale heating and vertical motion because there is a strong anvil componen...
3,813 citations
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TL;DR: Specialized experiments with atmosphere and coupled models show that the main damping mechanism for sea ice region surface temperature is reduced upward heat flux through the adjacent ice-free oceans resulting in reduced atmospheric heat transport into the region.
Abstract: The potential for sea ice-albedo feedback to give rise to nonlinear climate change in the Arctic Ocean – defined as a nonlinear relationship between polar and global temperature change or, equivalently, a time-varying polar amplification – is explored in IPCC AR4 climate models. Five models supplying SRES A1B ensembles for the 21 st century are examined and very linear relationships are found between polar and global temperatures (indicating linear Arctic Ocean climate change), and between polar temperature and albedo (the potential source of nonlinearity). Two of the climate models have Arctic Ocean simulations that become annually sea ice-free under the stronger CO 2 increase to quadrupling forcing. Both of these runs show increases in polar amplification at polar temperatures above-5 o C and one exhibits heat budget changes that are consistent with the small ice cap instability of simple energy balance models. Both models show linear warming up to a polar temperature of-5 o C, well above the disappearance of their September ice covers at about-9 o C. Below-5 o C, surface albedo decreases smoothly as reductions move, progressively, to earlier parts of the sunlit period. Atmospheric heat transport exerts a strong cooling effect during the transition to annually ice-free conditions. Specialized experiments with atmosphere and coupled models show that the main damping mechanism for sea ice region surface temperature is reduced upward heat flux through the adjacent ice-free oceans resulting in reduced atmospheric heat transport into the region.
1,356 citations
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06 Nov 2006TL;DR: A comprehensive unified treatment of atmospheric and oceanic fluid dynamics is provided in this paper, including rotation and stratification, vorticity, scaling and approximations, and wave-mean flow interactions and turbulence.
Abstract: Fluid dynamics is fundamental to our understanding of the atmosphere and oceans. Although many of the same principles of fluid dynamics apply to both the atmosphere and oceans, textbooks tend to concentrate on the atmosphere, the ocean, or the theory of geophysical fluid dynamics (GFD). This textbook provides a comprehensive unified treatment of atmospheric and oceanic fluid dynamics. The book introduces the fundamentals of geophysical fluid dynamics, including rotation and stratification, vorticity and potential vorticity, and scaling and approximations. It discusses baroclinic and barotropic instabilities, wave-mean flow interactions and turbulence, and the general circulation of the atmosphere and ocean. Student problems and exercises are included at the end of each chapter. Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-Scale Circulation will be an invaluable graduate textbook on advanced courses in GFD, meteorology, atmospheric science and oceanography, and an excellent review volume for researchers. Additional resources are available at www.cambridge.org/9780521849692.
1,022 citations
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Pusan National University1, University of Hawaii at Manoa2, Yonsei University3, Pohang University of Science and Technology4, Hobart Corporation5, Commonwealth Scientific and Industrial Research Organisation6, Ocean University of China7, University of Colorado Boulder8, Earth System Research Laboratory9, Georgia Institute of Technology10, University of Paris11, Pacific Marine Environmental Laboratory12, University Corporation for Atmospheric Research13, University of Washington14, Geophysical Fluid Dynamics Laboratory15, Leibniz Institute of Marine Sciences16, National Taiwan University17, Utah State University18, Monash University, Clayton campus19, University of Mary Washington20, Centre national de la recherche scientifique21, University of Reading22, Chonnam National University23, Met Office24, Ulsan National Institute of Science and Technology25, Asia-Pacific Economic Cooperation26, Bureau of Meteorology27, China Meteorological Administration28, University of New South Wales29, University of Exeter30, Chinese Academy of Sciences31, Hanyang University32, Gwangju Institute of Science and Technology33
TL;DR: A synopsis of the current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system is provided and a unifying framework that identifies the key factors for this complexity is proposed.
Abstract: El Nino events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities The alternation of warm El Nino and cold La Nina conditions, referred to as the El Nino–Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system
598 citations
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TL;DR: In this article, the authors measured the nonlinearity of ENSO by measuring the maximum potential intensity (MPI) index and the non-linear dynamic heating (NDH) index.
Abstract: El Nino events (warm) are often stronger than La Nina events (cold). This asymmetry is an intrinsic nonlinear characteristic of the El Nino-Southern Oscillation (ENSO) phenomenon. In order to measure the nonlinearity of ENSO, the maximum potential intensity (MPI) index and the nonlinear dynamic heating (NDH) of ENSO are proposed as qualitative and quantitative measures. The 1997/98 El Nino that was recorded as the strongest event in the past century and another strong El Nino event in 1982/83 nearly reached the MPI. During these superwarming events, the normal climatological conditions of the ocean and atmosphere were collapsed com- pletely. The huge bursts of ENSO activity manifested in these events are attributable to the nonlinear dynamic processes. Through a heat budget analysis of the ocean mixed layer it is found that throughout much of the ENSO episodes of 1982/83 and 1997/98, the NDH strengthened these warm events and weakened subsequent La Nina events. This led to the warm-cold asymmetry. It is also found that the eastward-propagating feature in these two El Nino events provided a favorable phase relationship between temperature and current that resulted in the strong nonlinear dynamical warming. For the westward-propagating El Nino events prior to the late 1970s (e.g., 1957/58 and 1972/73 ENSOs) the phase relationships between zonal temperature gradient and current and between the surface and subsurface temperature anomalies are unfavorable for nonlinear dynamic heating, and thereby the ENSO events are not strong.
442 citations