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Equator to pole difference of surface temperature (∆T ) for each obliquity. Black, red and blue symbols correspond to annual, DJF and JJA means, respectively. Positive values indicate higher temperatures at the equator.

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We present the evolution of the atmospheric variables that affect planetary climate by increasing the obliquity by using a general circulation model (PlaSim) coupled to a slab ocean with mixed layer flux correction. We increase the obliquity between 30° and 90° in 16 aquaplanets with liquid sea surface and perform the simulation allowing the sea ic...

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... 5: Latitudinal distribution of the annual mean surface temperature T s , for some representative cases of simulated aquaplanets (colour lines). Fig. 6 shows that the largest ∆T is found for δ = 30 • , for both the annual and seasonal means. ∆T decreases towards zero for δ = 52.5 • , and increases again for higher obliquities. ∆T = 0 K occurs in the annual mean at δ = 52.5 • and seasonally at δ = 47.5 • (summer) and δ = 57.5 • (winter), being thus the planets with the weakest synoptic ...

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... Planets with larger obliquities have larger amplitude seasonal variations (e.g. Williams & Kasting 1997;Spiegel et al. 2009;Armstrong et al. 2014;Nowajewski et al. 2018;Guendelman & Kaspi 2019) due to differences in seasonal stellar energy distribution at the planetary surface with increasing obliquity. Moderately high-obliquity planets also experience a more uniform distribution of stellar energy across the planetary surface on annual average, lead-ing these planets to be warmer on average than their low obliquity counterparts (e.g. ...
... Moderately high-obliquity planets also experience a more uniform distribution of stellar energy across the planetary surface on annual average, lead-ing these planets to be warmer on average than their low obliquity counterparts (e.g. Linsenmeier et al. 2015;Wang et al. 2016;Nowajewski et al. 2018;Kang 2019a;Guendelman & Kaspi 2019;Palubski et al. 2020;Komacek et al. 2021). ...
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Planetary obliquity is a first order control on planetary climate and seasonal contrast, which has a number of cascading consequences for life. How moderately high obliquity (obliquities greater than Earth's current obliquity up to 45$^{\circ}$) affects a planet's surface physically has been studied previously, but we lack an understanding of how marine life will respond to these conditions. We couple the ROCKE-3D general circulation model to the cGENIE 3D biogeochemical model to simulate the ocean biosphere's response to various planetary obliquities, bioessential nutrient inventories, and biospheric structure. We find that the net rate of photosynthesis increased by 35$\%$ and sea-to-air flux of biogenic oxygen doubled between the 0$^{\circ}$ and 45$^{\circ}$ obliquity scenarios, which is an equivalent response to doubling bioessential nutrients. Our results suggest that moderately high-obliquity planets have higher potential for biospheric oxygenation than their low-obliquity counterparts and that life on moderately high-obliquity habitable planets may be easier to detect with next generation telescopes. These moderately high-obliquity habitable planets may also be more conducive to the evolution of complex life.
... Furthermore, atmospheric dynamics effectively work to homogenize differential heating of the surface, creating a short-term response on the planet's global temperature. This differential heating is a result of the planet's obliquity, which governs the latitudinal distribution of incoming stellar radiation (Spiegel et al., 2009;Nowajewski et al., 2018). The Habitable Zone boundaries themselves also evolve over time. ...
... Even though the presence of water vapor in the atmospheres of terrestrial exoplanets can indicate habitability, it is necessary to perform exhaustive work to determine which species could survive under conditions of extreme humidity. For example, mammals are not capable of surviving hyperthermia produced under high air temperatures and high humidity conditions, so planets with extreme differential heating between latitudes may be uninhabitable for them, despite having liquid water on their surface (Nowajewski et al., 2018). Furthermore, many animals (including all mammals) may not survive in atmospheres with CO2 (N2) pressures exceeding ∼0.1 bars (Ramirez, 2020). ...
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Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth from local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency among them, being different in function to those used by ecologists. Habitability models are not only used to determine whether environments are habitable, but they also are used to characterize what key factors are responsible for the gradual transition from low to high habitability states. Here we review and compare some of the different models used by ecologists and astrobiologists and suggest how they could be integrated into new habitability standards. Such standards will help improve the comparison and characterization of potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science, and the synergy between ecologists and astrobiologists is necessary to expand our understanding of the habitability of Earth, the Solar System, and extrasolar planets.
... Furthermore, atmospheric dynamics effectively work to homogenize differential heating of the surface, creating a short-term response on the planet's global temperature. This differential heating is a result of the planet's obliquity, which governs the latitudinal distribution of incoming stellar radiation (Spiegel et al., 2009;Nowajewski et al., 2018). The Habitable Zone boundaries themselves also evolve over time. ...
... Even though the presence of water vapor in the atmospheres of terrestrial exoplanets can indicate habitability, it is necessary to perform exhaustive work to determine which species could survive under conditions of extreme humidity. For example, mammals are not capable of surviving hyperthermia produced under high air temperatures and high humidity conditions, so planets with extreme differential heating between latitudes may be uninhabitable for them, despite having liquid water on their surface (Nowajewski et al., 2018). Furthermore, many animals (including all mammals) may not survive in atmospheres with CO2 (N2) pressures exceeding ∼0.1 bars (Ramirez, 2020). ...
Preprint
Full-text available
Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth from local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency among them, being different in function to those used by ecologists. Habitability models are not only used to determine if environments are habitable or not, but they also are used to characterize what key factors are responsible for the gradual transition from low to high habitability states. Here we review and compare some of the different models used by ecologists and astrobiologists and suggest how they could be integrated into new habitability standards. Such standards will help to improve the comparison and characterization of potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science and the synergy between ecologists and astrobiologists is necessary to expand our understanding of the habitability of Earth, the Solar System, and extrasolar planets.
... This results in a sizable gap between the community's modeling capability and the need for theoretical models to underpin interpretation of observations (Ramirez et al. 2018). (Dekker et al. 2010;Garreaud et al. 2010;Haberkorn et al. 2012;Nowajewski et al. 2018), paleoclimate and snowball climate dynamics (Lucarini et al. 2010;Boschi et al. 2013;Linsenmeier et al. 2015;Paradise & Menou 2017;Paradise et al. 2019c), and synchronously rotating and slow-rotating planets (Checlair et al. 2017;Abbot et al. 2018;Checlair et al. 2019b;Paradise et al. 2021b). PlaSim is a fast GCM, able to model a year of climate in under a minute of wall-time (Paradise & Menou 2017). ...
Preprint
The discovery of a large number of terrestrial exoplanets in the habitable zones of their stars, many of which are qualitatively different from Earth, has led to a growing need for fast and flexible 3D climate models, which could model such planets and explore multiple possible climate states and surface conditions. We respond to that need by creating ExoPlaSim, a modified version of the Planet Simulator (PlaSim) that is designed to be applicable to synchronously rotating terrestrial planets, planets orbiting stars with non-solar spectra, and planets with non-Earth-like surface pressures. In this paper we describe our modifications, present validation tests of ExoPlaSim's performance against other GCMs, and demonstrate its utility by performing two simple experiments involving hundreds of models. We find that ExoPlaSim agrees qualitatively with more-sophisticated GCMs such as ExoCAM, LMDG, and ROCKE-3D, falling within the ensemble distribution on multiple measures. The model is fast enough that it enables large parameter surveys with hundreds to thousands of models, potentially enabling the efficient use of a 3D climate model in retrievals of future exoplanet observations. We describe our efforts to make ExoPlaSim accessible to non-modellers, including observers, non-computational theorists, students, and educators through a new Python API and streamlined installation through pip, along with online documentation.
... Un planeta de este tipo presentará cambios significativos en la actividad atmosférica al aumentar su oblicuidad, ya que, a medida que la inclinación aumenta, las mayores temperaturas se producen en los polos. El cambio se produce en las oblicuidades sobre 54°, donde las masas de aire se mueven hacia el ecuador, la que se convierte en la región con menor temperatura, invirtiendo el transporte de energía que vemos en la Tierra (Nowajewski et al., 2018). ...
Article
TAMAÑO, FORMA y FUNCIÓN EN LA NATURALEZA Los sistemas complejos: puentes entre la física y otras disciplinas Héctor L. Mancini RESÚMEN Este trabajo de divulgación presenta una panorámica, necesariamente limitada por la extensión, de las formas o patrones que se repiten en la naturaleza a muchas escalas. Esas estructuras son parte, o lo han sido, de sistemas dinámicos complejos fuera del equilibrio, es decir, productos del movimiento de la materia. Algunas, como las formas derivadas de las espirales geométricas, se extienden desde escalas moleculares a las astronómicas y son el eje director de este trabajo, que describe algunas pocas características desde las galaxias hasta la doble hélice del ADN (DNA). A su lado, se mencionan otras formas, también frecuentes tanto en la naturaleza como en experimentos de laboratorio, que suelen ser un banco de prueba para la teoría dinámica de los sistemas no lineales. ABSTRACT This dissemination work presents an overview, necessarily limited by the extent, of the forms or patterns that are repeated in nature at many scales. These structures are part, or have been, of complex dynamic systems out of equilibrium, that is, products of the movement of matter. Some, such as shapes derived from geometrical spirals, range from molecular to astronomical scales and are the focus of this work, which describes a few features from the DNA double helix to Galaxies. Alongside it, other forms mentioned are also frequent both in nature and in laboratory experiments, which are usually a test bed for the theory of Nonlinear Dynamical Systems.
... The model has been used extensively to study Earthlike climates, snowball climates, Martian analogues, and tidally-locked planets [e.g. 1,2,4,6,9,10,12]. We have modified the model to expand the range of planets that can be modeled to include planets with surface pressures significantly different from Earth's [8,7]. ...
Preprint
As the number of known exoplanets has climbed into the thousands, efforts by theorists to understand the diversity of climates that may exist on terrestrial planets in the habitable zone have also accelerated. These efforts have ranged from analytical, to simple 0-D, 1-D, and 2-D models, to highly-sophisticated 3D global climate models (GCMs) adapted from Earth climate and weather models. The advantage of the latter is that fewer physical processes are reduced to simple parameterizations and empirical fits, and may instead be represented by physically-motivated algorithms. However, many such models are difficult to use, and take a long time to reach a converged state relative to simpler models, thereby limiting the amount of parameter space that can be explored. We use PlaSim, a 3D climate model of intermediate complexity, to bridge this gap, allowing us to produce hundreds to thousands of model outputs that have reached energy balance equilibrium at the surface and top of the atmosphere. We are making our model outputs available to the community in a permanent Dataverse repository (https://dataverse.scholarsportal.info/dataverse/kmenou). A subset of our model outputs can be used directly with external spectral postprocessing tools, and we have used them with petitRADTRANS and SBDART in order to create synthetic observables representative of fully-3D climates. Another natural use of this repository will be to use more-sophisticated GCMs to cross-check and verify PlaSim's results, and to explore in more detail those regions of the exoplanet parameter space identified in our PlaSim results as being of particular interest. We will continue to add models to this repository in the future, including more than 1000 models in the short- to medium-term future, expanding the diversity of climates represented therein.
... Thus, the presence of liquid water on the surface also depends on the planet's atmospheric dynamics, which effectively work to homogenize differential heating of the surface, creating a short-term response on the planet's global temperature. This differential heating is a result of the planet's obliquity, which governs the latitudinal distribution of incoming stellar radiation (Nowajewski et al ., 2018). ...
... Even though the presence of water vapor in the atmospheres of terrestrial exoplanets can indicate habitability, it is necessary to perform exhaustive work to determine which species could survive under conditions of extreme humidity. For example, mammals are not capable of surviving hyperthermia produced under high air temperatures and high humidity conditions, so planets with extreme differential heating between latitudes may be uninhabitable for them despite having liquid water on their surface (Nowajewski et al ., 2018). ...
Preprint
Full-text available
Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth from local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency between them and different in function to those used by ecologists. In this white paper, we suggest a mass-energy habitability model as an example of how to adapt and expand the models used by ecologists to the astrobiology field. We propose to implement these models into a NASA Habitability Standard (NHS) to standardize the habitability objectives of planetary missions. These standards will help to compare and characterize potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science. The synergy between the methods used by ecologists and astrobiologists will help to integrate and expand our understanding of the habitability of Earth, the Solar System, and exoplanets.
... Oglesby and Ogg 1998;Jenkins 2000) and habitability of exoplanets (e.g. Williams and Pollard 2003;Ferreira et al. 2014;Armstrong et al. 2014;Linsenmeier et al. 2015;Wang et al. 2016;Nowajewski et al. 2018;Kang 2019a, b). There have been a few studies on the dynamics of the atmospheric circulation at high obliquity (e.g. ...
Article
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The seasonal response of the poleward extent of continental precipitation maxima to high obliquity and its controlling mechanisms are examined using the NCAR-CESM and Budyko-Sellers energy balance model. In CESM, the latitude of the poleward-most continental precipitation maximum (denoted as $${\phi }_{mp})$$ migrates poleward with increased obliquity, but is limited to equatorward of the latitude of maximum daily insolation. Some insight is gained on the controlling mechanism of the migration of $${\phi }_{mp}$$ in the Budyko–Sellers model, assuming $${\phi }_{mp}$$ coinciding with the position of maximum surface moist static energy (denoted as $${\Theta }_{mp}$$) as in the present-day observation and CESM pre-industrial simulation. Heat capacity exerts a primary control on $${\phi }_{mp}$$ such that $${\phi }_{mp}$$ is determined by the position of maxima of accumulated insolation over the radiative relaxation time and therefore lies equatorward of the maximum daily insolation. Variations of surface albedo and horizontal heat transport, as secondary effects, further shift the $${\phi }_{mp}$$. This understanding from the Budyko-Sellers model, however, fails in CESM in the case of high obliquity of 40°, with $${\phi }_{mp}$$ now lying equatorward of $${\Theta }_{mp}$$. This separation between $${\phi }_{mp}$$ and $${\Theta }_{mp}$$ is explained by the constraint of rotation on the latitudinal range of weak temperature gradients, which is the prerequisite for the prediction of $${\phi }_{mp}$$ from $${\Theta }_{mp}$$. When the rotation rate is reduced, the latitudinal range of weak temperature gradients expands poleward roughly following the change of the equatorial Rossby radius, allowing $${\phi }_{mp}$$ moving close to $${\Theta }_{mp}$$.
... Such a possibility is intricately contingent upon multiple factors, including the amount of insolation, tidal heating, and other heat sources available to exomoons (Heller & Barnes 2013;Dobos, Heller & Turner 2017), as well as their orbital stability (Gong et al. 2013;Hong et al. 2015;Spalding, Batygin & Adams 2016;Alvarado-Montes, Zuluaga & Sucerquia 2017;Zollinger, Armstrong & Heller 2017;Grishin, Lai & Perets 2018;Hong et al. 2018), atmosphere (Lammer et al. 2014;Heller & Barnes 2015) and the magnetic field of either satellite or planet (Heller & Zuluaga 2013). Massive exomoons are also important since they can prevent large chaotic variations to their host planet's obliquity (Sasaki & Barnes 2014), thereby creating a more stable climate which may be essential to the survival of life on a (solid and in the habitable zone) planet (Nowajewski et al. 2018). It has also been shown that water-bearing exomoons are in principal capable of retaining their water as their host stars go through their high-luminosity stellar evolution phases, and so they can host life or provide the necessary water for supporting life even around evolved compact stars (Malamud & Perets 2017). ...
Article
Exomoons orbiting terrestrial or superterrestrial exoplanets have not yet been discovered; their possible existence and properties are therefore still an unresolved question. Here, we explore the collisional formation of exomoons through giant planetary impacts. We make use of smooth particle hydrodynamical collision simulations and survey a large phase space of terrestrial/superterrestrial planetary collisions. We characterize the properties of such collisions, finding one rare case in which an exomoon forms through a graze and capture scenario, in addition to a few graze and merge or hit and run scenarios. Typically however, our collisions form massive circumplanetary discs, for which we use follow-up N-body simulations in order to derive lower limit mass estimates for the ensuing exomoons. We investigate the mass, long-term tidal-stability, composition and origin of material in both the discs and the exomoons. Our giant impact models often generate relatively iron-rich moons that form beyond the synchronous radius of the planet, and would thus tidally evolve outward with stable orbits, rather than be destroyed. Our results suggest that it is extremely difficult to collisionally form currently-detectable exomoons orbiting superterrestrial planets, through single giant impacts. It might be possible to form massive, detectable exomoons through several mergers of smaller exomoons, formed by multiple impacts, however more studies are required in order to reach a conclusion. Given the current observational initiatives, the search should focus primarily on more massive planet categories. However, about a quarter of the exomoons predicted by our models are approximately Mercury-mass or more, and are much more likely to be detectable given a factor 2 improvement in the detection capability of future instruments, providing further motivation for their development.
... PlaSim has been used extensively for Earth-like climates (e.g. Fraedrich et al., 2005;Boschi et al., 2013;Holden et al., 2016;Nowajewski et al., 2018;D'Errico et al., 2018), and we do not wish to make modifications that would require significant re-tuning and re-validation on the modern Earth climate. We therefore accept the disagreement at the surface, noting its consistency across surface pressure, as a difference in model parameterization, and take the agreement between PlaSim and SBDART in outgoing shortwave flux and therefore total shortwave energy budget as an indication of the validity of our modifications for the present study. ...
Preprint
A large number of studies have responded to the growing body of confirmed terrestrial habitable zone exoplanets by presenting models of various possible climates. However, the impact of the partial pressure of background gases such as N$_2$ has been poorly-explored, despite the abundance of N$_2$ in Earth's atmosphere and the lack of constraints on its typical abundance in terrestrial planet atmospheres. We use PlaSim, a fast 3D climate model, to simulate many hundreds of climates with varying N$_2$ partial pressures, insolations, and surface characteristics to identify the impact of the background gas partial pressure on the climate. We find that the climate's response is nonlinear and highly sensitive to the background gas partial pressure. We identify pressure broadening of CO$_2$ and H$_2$O absorption lines, amplification of warming or cooling by the water vapor greenhouse positive feedback, heat transport efficiency, and cooling through Rayleigh scattering as the dominant competing mechanisms that determine the equilibrium climate for a given N$_2$ partial pressure. Finally, we show that different amounts of N$_2$ should have a significant effect on broadband reflected light observations of terrestrial exoplanets.