18 research outputs found
Ammonia Abundance Derived from Juno MWR and VLA Observations of Jupiter
The vertical distribution of trace gases in planetary atmospheres can be
obtained with observations of the atmosphere's thermal emission. Inverting
radio observations to recover the atmospheric structure, however, is
non-trivial, and the solutions are degenerate. We propose a modeling framework
to prescribe a vertical distribution of trace gases that combines a
thermo-chemical equilibrium model {based on a vertical temperature structure
and compare these results to models where ammonia can vary between pre-defined
pressure nodes}. To this means we retrieve nadir brightness temperatures and
limb-darkening parameters, together with their uncertainties, from the Juno
Microwave Radiometer (MWR). We then apply this framework to MWR observations
during Juno's first year of operation (Perijove passes 1 - 12) and to
longitudinally-averaged latitude scans taken with the upgraded Very Large Array
(VLA) (de Pater 2016,2019a). We use the model to constrain the distribution of
ammonia between -60 and 60 latitude and down to 100 bar. We
constrain the ammonia abundance to be ppm
( solar abundance), and find a depletion of
ammonia down to a depth of 20 bar, which supports the existence of
processes that deplete the atmosphere below the ammonia and water cloud layers.
At the equator we find an increase of ammonia with altitude, while the zones
and belts in the mid-latitudes can be traced down to levels where the
atmosphere is well-mixed. The latitudinal variation in the ammonia abundance
appears to be opposite to that shown at higher altitudes, which supports the
existence of a stacked-cell circulation model.Comment: Accepted by Planetary Science Journa
Heat-Flux Limited Cloud Activity and Vertical Mixing in Giant Planet Atmospheres with an Application to Uranus and Neptune
Storms operated by moist convection and the condensation of or
have been observed on Uranus and Neptune. However, the mechanism
of cloud formation, thermal structure, and mixing efficiency of ice giant
weather layers remains unclear. In this paper, we show that moist convection is
limited by heat transport on giant planets, especially on ice giants where
planetary heat flux is weak. Latent heat associated with condensation and
evaporation can efficiently bring heat across the weather layer through
precipitations. This effect was usually neglected in previous studies without a
complete hydrological cycle. We first derive analytical theories and show the
upper limit of cloud density is determined by the planetary heat flux and
microphysics of clouds but independent of the atmospheric composition. The eddy
diffusivity of moisture depends on the heat fluxes, atmospheric composition,
and gravity of the planet but is not directly related to cloud microphysics. We
then conduct convection- and cloud-resolving simulations with SNAP to validate
our analytical theory. The simulated cloud density and eddy diffusivity are
smaller than the results acquired from the equilibrium cloud condensation model
and mixing length theory by several orders of magnitude but consistent with our
analytical solutions. Meanwhile, the mass-loading effect of and
leads to superadiabatic and stable weather layers. Our simulations
produced three cloud layers that are qualitatively similar to recent
observations. This study has important implications for cloud formation and
eddy mixing in giant planet atmospheres in general and observations for future
space missions and ground-based telescopes.Comment: 23 pages, 7 figures, and 2 tables. Accepted for publication in PS
Potential for Solar System Science with the ngVLA
Radio wavelength observations of solar system bodies are a powerful method of
probing many characteristics of those bodies. From surface and subsurface, to
atmospheres (including deep atmospheres of the giant planets), to rings, to the
magnetosphere of Jupiter, these observations provide unique information on
current state, and sometimes history, of the bodies. The ngVLA will enable the
highest sensitivity and resolution observations of this kind, with the
potential to revolutionize our understanding of some of these bodies. In this
article, we present a review of state-of-the-art radio wavelength observations
of a variety of bodies in our solar system, varying in size from ring particles
and small near-Earth asteroids to the giant planets. Throughout the review we
mention improvements for each body (or class of bodies) to be expected with the
ngVLA. A simulation of a Neptune-sized object is presented in Section 6.
Section 7 provides a brief summary for each type of object, together with the
type of measurements needed for all objects throughout the Solar System
Mapping satellite surfaces and atmospheres with ground-based radio interferometry
Ground-based interferometry at mm-cm wavelengths provides a powerful tool for characterizing satellite surfaces and atmospheres. We present the science enabled by the ALMA (current) and ngVLA (proposed) arrays, including recent results as well as future work in the context of planned and proposed spacecraft missions
Mapping satellite surfaces and atmospheres with ground-based radio interferometry
Ground-based interferometry at mm-cm wavelengths provides a powerful tool for characterizing satellite surfaces and atmospheres. We present the science enabled by the ALMA (current) and ngVLA (proposed) arrays, including recent results as well as future work in the context of planned and proposed spacecraft missions
Potential for Solar System Science with the ngVLA
Radio wavelength observations of solar system bodies are a powerful method of probing many characteristics of those bodies. From surface and subsurface, to atmospheres (including deep atmospheres of the giant planets), to rings, to the magnetosphere of Jupiter, these observations provide unique information on the current state, and sometimes history, of the bodies. The ngVLA will enable the highest sensitivity and resolution observations of this kind, with the potential to revolutionize our understanding of some of these bodies. In this article, we present a review of state-of-the-art radio wavelength observations of a variety of bodies in our solar system, varying in size from ring particles and small near-Earth asteroids to the giant planets. Throughout the review we mention improvements for each body (or class of bodies) to be expected with the ngVLA. A simulation of a Neptune-sized object is presented in Section 6. Section 7 provides a brief summary for each type of object, together with the type of measurements needed for all objects throughout the Solar System
Potential for Solar System Science with the ngVLA
Radio wavelength observations of solar system bodies are a powerful method of probing many characteristics of those bodies. From surface and subsurface, to atmospheres (including deep atmospheres of the giant planets), to rings, to the magnetosphere of Jupiter, these observations provide unique information on current state, and sometimes history, of the bodies. The ngVLA will enable the highest sensitivity and resolution observations of this kind, with the potential to revolutionize our understanding of some of these bodies. In this article, we present a review of state-of-the-art radio wavelength observations of a variety of bodies in our solar system, varying in size from ring particles and small near-Earth asteroids to the giant planets. Throughout the review we mention improvements for each body (or class of bodies) to be expected with the ngVLA. A simulation of a Neptune-sized object is presented in Section 6. Section 7 provides a brief summary for each type of object, together with the type of measurements needed for all objects throughout the Solar System