Spectral determination of the colour and vertical structure of dark spots in Neptune’s atmosphere

Previous observations of dark vortices in Neptune’s atmosphere, such as Voyager 2’s Great Dark Spot (1989), have been made in only a few broad-wavelength channels, hampering efforts to determine these vortices’ pressure levels and darkening processes. We analyse spectroscopic observations of a dark spot on Neptune identified by the Hubble Space Telescope as NDS-2018; the spectral observations were made in 2019 by the Multi Unit Spectroscopic Explorer (MUSE) of the Very Large Telescope (Chile). The MUSE medium-resolution 475–933 nm reflection spectra allow us to show that dark spots are caused by darkening at short wavelengths (700 nm). This bright feature is much deeper than previously studied dark-spot companion clouds and may be connected with the circulation that generates and sustains such spots

Strong Temporal Variation Over One Saturnian Year: From Voyager to Cassini

Here we report the combined spacecraft observations of Saturn acquired over one Saturnian year (~29.5 Earth years), from the Voyager encounters (1980–81) to the new Cassini reconnaissance (2009–10). The combined observations reveal a strong temporal increase of tropic temperature (~10 Kelvins) around the tropopause of Saturn (i.e., 50 mbar), which is stronger than the seasonal variability (~a few Kelvins). We also provide the first estimate of the zonal winds at 750 mbar, which is close to the zonal winds at 2000 mbar. The quasi-consistency of zonal winds between these two levels provides observational support to a numerical suggestion inferring that the zonal winds at pressures greater than 500 mbar do not vary significantly with depth. Furthermore, the temporal variation of zonal winds decreases its magnitude with depth, implying that the relatively deep zonal winds are stable with time

Longitudinal variability in Jupiter's zonal winds derived from multi-wavelength HST observations

Multi-wavelength Hubble Space Telescope (HST) images of Jupiter from the Outer Planets Atmospheres Legacy (OPAL) and Wide Field Coverage for Juno (WFCJ) programs in 2015, 2016, and 2017 are used to derive wind profiles as a function of latitude and longitude. Wind profiles are typically zonally averaged to reduce measurement uncertainties. However, doing this destroys any variations of the zonal-component of winds in the longitudinal direction. Here, we present the results derived from using a "sliding-window" correlation method. This method adds longitudinal specificity, and allows for the detection of spatial variations in the zonal winds. Spatial variations are identified in two jets: 1 at 17 degrees N, the location of a prominent westward jet, and the other at 7 degrees S, the location of the chevrons. Temporal and spatial variations at the 24 degrees N jet and the 5-m hot spots are also examined

Cuantificación hidrogeológica básica

Se explican las nociones básicas para obtener una visión global de la dinámica del ciclo del agua. Además, se exponen métodos sencillos y asequibles de cuantificación de la precipitación, evaporación y escorrentía, que permiten realizar balances hídricos elementales.It explained basic notions to obtain a global vision about the elemental hidrologic cycle. Horeover, it exposed easy and accesible methods to cuantifity the precipitation, evaporation and runoff, that permit obtain elemental water balances

Cuantificación hidrogeológica básica

Se explican las nociones básicas para obtener una visión global de la dinámica del ciclo del agua. Además, se exponen métodos sencillos y asequibles de cuantificación de la precipitación, evaporación y escorrentía, que permiten realizar balances hídricos elementales.It explained basic notions to obtain a global vision about the elemental hidrologic cycle. Horeover, it exposed easy and accesible methods to cuantifity the precipitation, evaporation and runoff, that permit obtain elemental water balances

Disruption of Saturn’s quasi-periodic equatorial oscillation by the great northern storm

The equatorial middle atmospheres of the Earth 1 , Jupiter 2 and Saturn 3,4 all exhibit a remarkably similar phenomenon-a vertical, cyclic pattern of alternating temperatures and zonal (east-west) wind regimes that propagate slowly downwards with a well-defined multi-year period. Earth's quasi-biennial oscillation (QBO) (observed in the lower stratospheric winds with an average period of 28 months) is one of the most regular, repeatable cycles exhibited by our climate system 1,5,6 , and yet recent work has shown that this regularity can be disrupted by events occurring far away from the equatorial region, an example of a phenomenon known as atmospheric teleconnection 7,8 . Here, we reveal that Saturn's equatorial quasi-periodic oscillation (QPO) (with an ~15-year period 3,9 ) can also be dramatically perturbed. An intense springtime storm erupted at Saturn's northern mid-latitudes in December 2010 10-12 , spawning a gigantic hot vortex in the stratosphere at 40° N that persisted for three years 13 . Far from the storm, the Cassini temperature measurements showed a dramatic ~10 K cooling in the 0.5-5 mbar range across the entire equatorial region, disrupting the regular QPO pattern and significantly altering the middle-atmospheric wind structure, suggesting an injection of westward momentum into the equatorial wind system from waves generated by the northern storm. Hence, as on Earth, meteorological activity at mid-latitudes can have a profound effect on the regular atmospheric cycles in Saturn's tropics, demonstrating that waves can provide horizontal teleconnections between the phenomena shaping the middle atmospheres of giant planets

Detection of a Warm Thermal Anomaly in Jupiter's Stratosphere

International audienceWe present 3-dimensional thermal mapping results of Jupiter's stratosphere between atmospheric pressures of 30 and 0.01 mbar. By scan-mapping Jupiter with TEXES (the Texas Echelon cross-dispersed Echelle Spectrograph) mounted on the 3-m NASA Infrared Telescope Facility atop Maunakea, we measure methane (CH<SUB>4</SUB>) emission features across Jupiter with complete zonal coverage and meridional coverage between 40° South and 40° North planetocentric latitude. Since methane is well mixed in Jupiter's stratosphere, variations of the methane emission in the CH<SUB>4</SUB> nu<SUB>4</SUB> vibrational band at 8 mum are caused by variations in the atmospheric temperature. Line-by-line radiative transfer modeling of these thermal emission maps reveal a large scale ( 15° in latitude and 30° in longitude) thermal anomaly reaching 15 K above ambient centered at 28°N latitude and 176° W longitude (System III) at a pressure of 1.2 mbar. A map retrieved a week later shows how this anomaly moved and evolved. We will present the observations, radiative-transfer modeling results, and analysis of the thermal anomaly and its evolution

Detection of a Warm Thermal Anomaly in Jupiter's Stratosphere

International audienceWe present 3-dimensional thermal mapping results of Jupiter's stratosphere between atmospheric pressures of 30 and 0.01 mbar. By scan-mapping Jupiter with TEXES (the Texas Echelon cross-dispersed Echelle Spectrograph) mounted on the 3-m NASA Infrared Telescope Facility atop Maunakea, we measure methane (CH<SUB>4</SUB>) emission features across Jupiter with complete zonal coverage and meridional coverage between 40° South and 40° North planetocentric latitude. Since methane is well mixed in Jupiter's stratosphere, variations of the methane emission in the CH<SUB>4</SUB> nu<SUB>4</SUB> vibrational band at 8 mum are caused by variations in the atmospheric temperature. Line-by-line radiative transfer modeling of these thermal emission maps reveal a large scale ( 15° in latitude and 30° in longitude) thermal anomaly reaching 15 K above ambient centered at 28°N latitude and 176° W longitude (System III) at a pressure of 1.2 mbar. A map retrieved a week later shows how this anomaly moved and evolved. We will present the observations, radiative-transfer modeling results, and analysis of the thermal anomaly and its evolution

Detection of a Warm Thermal Anomaly in Jupiter's Stratosphere

International audienceWe present 3-dimensional thermal mapping results of Jupiter's stratosphere between atmospheric pressures of 30 and 0.01 mbar. By scan-mapping Jupiter with TEXES (the Texas Echelon cross-dispersed Echelle Spectrograph) mounted on the 3-m NASA Infrared Telescope Facility atop Maunakea, we measure methane (CH<SUB>4</SUB>) emission features across Jupiter with complete zonal coverage and meridional coverage between 40° South and 40° North planetocentric latitude. Since methane is well mixed in Jupiter's stratosphere, variations of the methane emission in the CH<SUB>4</SUB> nu<SUB>4</SUB> vibrational band at 8 mum are caused by variations in the atmospheric temperature. Line-by-line radiative transfer modeling of these thermal emission maps reveal a large scale ( 15° in latitude and 30° in longitude) thermal anomaly reaching 15 K above ambient centered at 28°N latitude and 176° W longitude (System III) at a pressure of 1.2 mbar. A map retrieved a week later shows how this anomaly moved and evolved. We will present the observations, radiative-transfer modeling results, and analysis of the thermal anomaly and its evolution

Evolution of a dark vortex on Neptune with transient secondary features

Dark spots on Neptune observed by Voyager and the Hubble Space Telescope are thought to be anticyclones with lifetimes of a few years, in contrast with very long-lived anticyclones in Jupiter and Saturn. The full life cycle of any Neptune dark spot has not been captured due to limited temporal coverage, but our Hubble observations of a recent feature, NDS-2018, provide the most complete long-term observational history of any dark vortex on Neptune. Past observations suggest some dark spots meet their demise by fading and dissipating without migrating meridionally. On the other hand, simulations predict a second pathway with equatorward migration and disruption. Our HST observations suggest NDS-2018 is following the second pathway. Some of the HST observations reveal transient dark features with widths of about 4000 to 9000 km, at latitudes between NDS-2018 and the equator. The secondary dark features appeared before changes in the meridional migration of NDS-2018 were seen. These features have somewhat smaller size and much smaller contrast compared to the main dark spot. Discrete secondary dark features of this scale have never been seen near previous dark spots, but global-scale dark bands are associated with several previous dark spots in addition to NDS-2018. The absolute photometric contrast of NDS-2018 (as large as 19%) is greater than previous dark spots, including the Great Dark Spot seen by Voyager. New simulations suggest that vortex internal circulation is weak relative to the background vorticity, presenting a clearly different case from stronger anticyclones observed on Jupiter and Saturn