EPIC simulations of Neptune’s dark spots using an active cloud microphysical model

Hadland, Nathan; Sankar, Ramanakumar; LeBeau, Raymond P.; Palotai, Csaba

doi:10.1093/mnras/staa1799

Cited by 12 publications

(9 citation statements)

References 26 publications

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“…Vortex oscillations—in both shape and location—were seen in Voyager Neptune imaging (Smith et al., 1989; Sromovsky et al., 1993, 2002), and oscillations provide a major constraint for dynamical models (LeBeau & Dowling, 1998; Hadland et al., 2020; Polvani et al., 1990). A triple‐vortex system on Saturn oscillated in longitude (del Río‐Gaztelurrutia et al., 2018), although long‐lived single Saturnian vortices did not oscillate in Voyager observations (Sánchez‐Lavega et al., 2000).…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Horizontal Winds in Jupiter's Great Red Spot From One Jovian Year of HST/WFC3 Maps

Wong

Marcus

Simon-Miller

et al. 2021

Geophysical Research Letters

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The Great Red Spot is an enduring large anticyclone in Jupiter's atmosphere, situated in the South Tropical Zone (Figure 1). Anticyclonic flow in this zone is perturbed over the northern edge of the GRS so that it locally protrudes into the typically dark and reddish South Equatorial Belt (SEB) to the north. The SEB features dramatic global-scale changes in coloration, cloud properties, and convective activity (e.g., Fletcher et al., 2011Fletcher et al., , 2017Rogers, 1995;Sánchez-Lavega & Gómez, 1996), but the most notable change in the GRS itself is more monotonic in nature: a continuous decrease in size over more than 100 years of accurate observations (Simon et al., 2018).The size and longevity of the GRS make it unique among outer solar system vortices, yet it also serves as an archetype of a class of "pancake vortices"-anticyclones embedded in stably stratified fluids-also including vortices like the dark spots on Neptune and salt lens eddies in the Earth's oceans (e.g., Dowling, 1995;Hassanzadeh et al., 2012;Yim et al., 2016). Pancake vortices have a thickness much smaller than their horizontal dimensions, like the GRS whose horizontal scale is some 50 times greater than vertical scale, according to theoretical arguments based on laboratory experiments and Jovian vortex velocity fields (Lemasquerier et al., 2020). Terrestrial ocean eddies transport heat meridionally by both stirring (turbulent) and trapping (bulk transport) mechanisms (Sun et al., 2018). Trapping is limited on Jupiter because major vortices are bounded by jets that limit meridional migration, although trapping could be significant on Saturn, where poleward migration of the anticyclone created by the 2010 Great White Storm was observed

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Section: Discussionmentioning

confidence: 99%

Evolution of the Horizontal Winds in Jupiter's Great Red Spot From One Jovian Year of HST/WFC3 Maps

Wong

Marcus

Simon-Miller

et al. 2021

Geophysical Research Letters

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“…From our microphysics scheme, we can diagnose the particle sizes and terminal velocity, in a similar fashion to Hadland et al (2020), who did the same for methane clouds on Neptune. In the case of ice clouds, we assume that each grid cell has an average cloud particle size.…”

Section: Terminal Velocity and Dissipation Of Cloud Particlesmentioning

confidence: 83%

“…We vary the abundance of water in the deep atmosphere between 0.5×, 1× and 2× the nominal solar [O/H] ratio and 2× and 4× the nominal [N/H] ratio to investigate the effect on the dynamics of the wave and resulting cloud formation. The addition of volatiles affects the molar mass, which affects the dynamics of large scale features, (e.g., Hadland et al 2020). However, in this case, the wave forms above the cloud, in a region where the added vapor mass is insignificant, the dynamics of the wave is unaffected by the amount of added volatiles.…”

Section: Water Clouds and Abundancementioning

confidence: 99%

The aftermath of convective events near Jupiter's fastest prograde jet: implications for clouds, dynamics and vertical wind shear

Sankar,

Klare,

Palotai

2021

Preprint

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The 24 • N jet borders the North Tropical Belt and North Tropical Zone, and is the fastest prograde jet on Jupiter, reaching speeds above 170 m/s. In this region, observations have shown several periodic convective plumes, likely from latent heat release from water condensation, which affect the cloud and zonal wind structure of the jet. We model this region with the Explicit Planetary hybrid-Isentropic Coordinate model using its active microphysics scheme to study the phenomenology of water and ammonia clouds within the jet region. On perturbing the atmosphere, we find that an upper tropospheric wave develops that directly influences the cloud structure within the jet. This wave travels at ∼ 75 m/s in our model, and leads to periodic chevron-shaped features in the ammonia cloud deck. These features travel with the wave speed, and are subsequently much slower than the zonal wind at the cloud deck. The cloud structure, and the slower drift rate, were both observed following the convective outbreak in this region in 2016 and 2020. We find that an upper level circulation is responsible for these cloud features in the aftermath of the convective outbursts. The comparatively slower observed drift rates of these features, relative to the wind speed of the jet, provides constraints on the vertical wind shear above the cloud tops, and we suggest that wind velocities determined from cloud tracking should correspond to a different altitude compared to the 680 hPa pressure level. We also diagnose the convective potential of the atmosphere due to water condensation, and find that it is strongly coupled to the wave.

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“…Sedimentation velocity is calculated beforehand for different particle sizes based on Pruppacher & Klett (2010), and fit to a power law as a function of diameter for different pressures, ensuring an accurate and quick treatment of precipitation (Hadland et al 2020). On Jupiter, these are derived for water and ammonia ice, rain and snow.…”

Section: Epic Model and Stratiform Cloud Schemementioning

confidence: 99%

A new convective parameterization applied to Jupiter: implications for water abundance near the $24^\circ$ N region

Sankar,

Palotai

2022

Preprint

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Jupiter's atmosphere features a variety of clouds that are formed from the interplay of chemistry and atmospheric dynamics, from the deep red color of the Great Red Spot to the high altitude white ammonia clouds present in the zones (bright bands in Jupiter's atmosphere). Beneath these upper level clouds, water condensation occurs, and sporadically leads to the formation of towering convective storms, driven by the release of large amounts of latent heat. These storms result in a widespread disruption of the cloud and dynamical structure of the atmosphere at the latitude where they form, making the study of these events paramount in understanding the dynamics at depth, and the role of water in the jovian atmosphere. In this work, we use the Explicit Planetary hybrid-Isentropic Coordinate (EPIC) General Circulation Model (GCM) to study the jovian atmosphere, with a focus on moist convective storm formation from water condensation. We present the addition of a sub-grid scale moist convective module to model convective water cloud formation. We focus on the 24 • N latitude, the location of a high speed jetstream, where convective upwellings have been observed every 4-5 years. We find that the potential of convection, and vertical mass and energy flux of the atmosphere is strongly correlated with the amount of water, and we determine an upper limit of the amount of water in the the region surrounding the jet as twice the solar [O/H] ratio.

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EPIC simulations of Neptune’s dark spots using an active cloud microphysical model

Cited by 12 publications

References 26 publications

Evolution of the Horizontal Winds in Jupiter's Great Red Spot From One Jovian Year of HST/WFC3 Maps

Evolution of the Horizontal Winds in Jupiter's Great Red Spot From One Jovian Year of HST/WFC3 Maps

The aftermath of convective events near Jupiter's fastest prograde jet: implications for clouds, dynamics and vertical wind shear

A new convective parameterization applied to Jupiter: implications for water abundance near the $24^\circ$ N region

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