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\"Floodplains provides an overview of floodplains and their management in temperate regions. It synthesizes decades of research on floodplain ecosystems, explaining hydrologic, geomorphic and ecological processes and how these processes can provide a range of benefits to society under appropriate management. Due to the widespread alteration of temperate floodplains, these benefits are often not realized. Drawing on the framework of reconciliation ecology, the authors explore how new concepts for floodplain ecosystem restoration and management can provide a broader range of benefits to society, ranging from healthy fish populations to flood-risk reduction. Case studies from California's Central Valley and elsewhere in temperate regions show how innovative management approaches are reshaping rivers and floodplains around the world.\"--Provided by publisher.

Floodplains provides an overview of floodplains and their management in temperate regions. It synthesizes decades of research on floodplain ecosystems, explaining hydrologic, geomorphic, and ecological processes and how under appropriate management these processes can provide benefits to society ranging from healthy fish populations to flood-risk reduction. Drawing on the framework of reconciliation ecology, the authors explore how new concepts for floodplain ecosystem restoration and management can increase these benefits. Additionally, they use case studies from California's Central Valley and other temperate regions to show how innovative management approaches are reshaping rivers and floodplains around the world.

Isca is a framework for the idealized modelling of the global circulation of planetary atmospheres at varying levels of complexity and realism. The framework is an outgrowth of models from the Geophysical Fluid Dynamics Laboratory in Princeton, USA, designed for Earth's atmosphere, but it may readily be extended into other planetary regimes. Various forcing and radiation options are available, from dry, time invariant, Newtonian thermal relaxation to moist dynamics with radiative transfer. Options are available in the dry thermal relaxation scheme to account for the effects of obliquity and eccentricity (and so seasonality), different atmospheric optical depths and a surface mixed layer. An idealized grey radiation scheme, a two-band scheme, and a multiband scheme are also available, all with simple moist effects and astronomically based solar forcing. At the complex end of the spectrum the framework provides a direct connection to comprehensive atmospheric general circulation models.For Earth modelling, options include an aquaplanet and configurable continental outlines and topography. Continents may be defined by changing albedo, heat capacity, and evaporative parameters and/or by using a simple bucket hydrology model. Oceanic Q fluxes may be added to reproduce specified sea surface temperatures, with arbitrary continental distributions. Planetary atmospheres may be configured by changing planetary size and mass, solar forcing, atmospheric mass, radiation, and other parameters. Examples are given of various Earth configurations as well as a giant planet simulation, a slowly rotating terrestrial planet simulation, and tidally locked and other orbitally resonant exoplanet simulations.The underlying model is written in Fortran and may largely be configured with Python scripts. Python scripts are also used to run the model on different architectures, to archive the output, and for diagnostics, graphics, and post-processing. All of these features are publicly available in a Git-based repository.

The climate of early Mars could have supported a complex hydrological system. Analysis of ancient deltaic deposits and valley networks reveals the presence of a planet-wide equipotential surface in the northern lowlands, indicative of the existence of a vast ocean on Mars 3.5 billion years ago. The climate of early Mars could have supported a complex hydrological system and possibly a northern hemispheric ocean covering up to one-third of the planet’s surface 1 , 2 , 3 , 4 , 5 . This notion has been repeatedly proposed 1 , 2 , 3 , 4 , 5 and challenged 6 , 7 over the past two decades, and remains one of the largest uncertainties in Mars research. Here, we used global databases of known deltaic deposits, valley networks 8 and present-day martian topography to test for the occurrence of an ocean on early Mars. The distribution of ancient martian deltas delineates a planet-wide equipotential surface within and along the margins of the northern lowlands. We suggest that the level reconstructed from the analysis of the deltaic deposits may represent the contact of a vast ocean covering the northern hemisphere of Mars around 3.5 billion years ago. This boundary is broadly consistent with palaeoshorelines suggested by previous geomorphologic, thermophysic and topographic analyses, and with the global distribution and age of ancient valley networks. Our findings lend credence to the hypothesis that an ocean formed on early Mars as part of a global and active hydrosphere.

On 4 May 2022, the seismometer on Mars observed the largest marsquake (S1222a) during its operation. One of the most specific features of S1222a is the long event duration lasting more than 8 hr, in addition to the clear appearance of body and surface waves. As demonstrated on Earth, by modeling a long‐lasting and scattered surface wave with the radiative transfer theory under the isotropic scattering condition, we estimated the scattering and intrinsic quality factors of Mars (Qs and Qi). This study especially focused on the frequency range between 0.05–0.09 Hz, where Qs and Qi have not been constrained yet. Our results revealed that Qi = 1,000–1,500 and Qs = 30–500. By summarizing the Martian Qi and Qs estimated so far and by comparing them with those of other celestial bodies, we found that, overall, the Martian scattering and absorption properties showed Earth‐like values. Plain Language Summary Since February 2019, NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport) has been conducting quasi‐continuous seismic observation for more than three years. The seismic data from Mars has contributed significantly to a better understanding of the interior structure and the seismicity of the red planet. On 4 May 2022 (1222 Martian days after landing), another key event occurred, called S1222a. The event showed the largest seismic moment release (magnitude 4.7) and extremely long duration (>8 hr) with intense seismic scattering. As demonstrated on Earth, the long‐lasting scattered waves are useful for retrieving information about the structural heterogeneity within a planet. In this study, by applying the radiative transfer theory—which considers the energy transportation from the seismic source to the observation point—to Mars, we evaluated the energy decay rate due to seismic scattering and energy absorption by a medium. By comparing our results with those of other solid bodies, we found that the Martian scattering and absorption features were closer to the terrestrial ones than to the lunar ones. Key Points We modeled the scattering effect of the largest marsquake (S1222a) using radiative transfer theory on a spherical Mars The inversion revealed that the intrinsic and scattering quality factors below 0.1 Hz are 1,000–1,500 and 30–500, respectively We summarized the Martian quality factors derived so far and found that they are relatively Earth‐like rather than Moon‐like

Understanding the composition of lavas erupted at the surface of the Earth is key to reconstruct the long‐term history of our planet. Recent geochemical analyses of ocean island basalt samples indicate the preservation of ancient mantle heterogeneities dating from the earliest stages of Earth's evolution (Péron & Moreira, 2018, https://doi.org/10.7185/geochemlet.1833), when a global magma ocean was present. Such observations contrast with fluid dynamics studies which demonstrated that in a magma ocean the convective motions, primarily driven by buoyancy, are extremely vigorous (Gastine et al., 2016, https://doi.org/10.1017/jfm.2016.659) and are therefore expected to mix heterogeneities within just a few minutes (Thomas et al., 2023, https://doi.org/10.1093/gji/ggad452). To elucidate this paradox we explored the effects of the Earth's rapid rotation on the stirring efficiency of a magma ocean, by performing state‐of‐the‐art fluid dynamics simulations of low‐viscosity, turbulent convective dynamics in a spherical shell. We found that rotational effects drastically affect the convective structure and the associated stirring efficiency. Rotation leads to the emergence of three domains with limited mass exchanges, and distinct stirring and cooling efficiencies. Still, efficient convective stirring within each region likely results in homogenization within each domain on timescales that are short compared with the solidification timescales of a magma ocean. However, the lack of mass exchange between these regions could lead to three or four large‐scale domains with internally homogeneous, but distinct compositions. The existence of these separate regions in a terrestrial magma ocean suggests a new mechanism to preserve distinct geochemical signatures dating from the earliest stages of Earth's evolution. Plain Language Summary Geochemical heterogeneities from short‐lived radionuclide parent‐daughter systems date back to the very beginning of Earth's history, because the parent element became extinct a few tens of millions years after the solar system formation. Yet, geochemical heterogeneities from short‐lived radioactive elements are observed in some present‐day ocean island basalts. These geochemical observations prompted us to explore the mixing efficiency of the young Earth, when its silicate mantle was at a liquid state. We conducted numerical simulations in three‐dimensional spherical geometry to study turbulent convection and stirring efficiency of magma ocean. For the flow regime with important rotational effects our results show that the magma ocean is separated in different domains (i.e., a polar, a columnar and an outer domain). Within each domain the convective stirring is very efficient, such that the mixing time of heterogeneities is short compared with the solidification timescales. Interestingly, we find that the mass exchange between domains is limited, leading to the possible preservation of large‐scale (domain size) heterogeneous reservoirs. This mechanism could explain how geochemical heterogeneities from the early Earth might be observed in modern ocean island basalts. Key Points Rotation can structure a magma ocean in different domains with distinct stirring efficiency and limited mass exchange Stirring efficiency in each domain leads to homogenization of heterogeneities in timescales short compared to solidification onset The limited mass exchange between the domains could allow to preserve large‐scale heterogeneous reservoirs over long timescales

Many objectives in geoscience and engineering require Earth surface elevations at greater temporospatial resolution and coverage than are currently available. This may be achieved with stereo imagery from large constellations of “small sats”, such as PlanetScope Doves. Obtaining Digital Surface Models (DSMs) of sufficient quality from these images is challenging due to their lower resolution and weaker stereo geometry relative to stereo mode satellites such as WorldView. The quality can be improved by utilizing their much larger numbers of repeat images, but this requires effective stereopair selection. To determine the stereo geometries required for obtaining quality DSMs from PlanetScope Dove imagery, we apply a new methodology for generating simulated stereo images of varying geometries using adjusted orientation parameters obtained by a self-calibrating bundle adjustment and validated by comparing the resulting rigorous sensor and rational function models. The accuracies of simulated stereo and multi-pair DSMs are then assessed through comparison to a reference DSM, providing the relationship between specific imaging geometries and DSM quality. Our results provide a basis for automated stereo imagery selection to enable large-scale DSM production from PlanetScope Dove imagery. Our methodology can be applied to other sources of stereo imagery and designing future satellite missions. In the future, we will further develop multi-pair matching algorithms for generating DSMs with Dove Classic images to improve both accuracy and quality that are otherwise limited by the weak stereo geometry of single stereo pairs.

Recent gullies on Mars are suspected to be the result of liquid‐water‐bearing flows. A formation from wet flows has been challenged by studies invoking granular (dry) flows. Our study focuses on the sinuous shapes observed for some of the recent Martian gullies. Sinuous gullies are found in locations and slopes (of 10°–15°) similar to straight gullies, and they are therefore related to the same formation processes. Numerical simulations of granular flows are performed here by introducing topographic variations such as obstacles, roughness, or slope changes that could possibly generate flow sinuosity. None of these simulations was able to reproduce sinuous shapes on a slope lower than 18° with friction angles typical of dry granular material. The only way to simulate sinuous shapes is to create small‐amplitude periodic variations of the topography of the deposit, an origin not supported by current Martian imagery. Given the presence of sinuosity in natural terrestrial debris flows, we have concluded that sinuous Martian gullies are better reproduced by liquid‐water‐bearing debris flows. Sinuous shapes in leveed flows are used to derive mechanical parameters from several Martian gullies using photoclinometry. Values in yield strength of 100–2200 Pa, velocities of 1.1–3.3 m s−1, and viscosities from 40 to 1040 Pa s are found, which are all within the range of values for terrestrial debris flows with various proportions of liquid water (20%–40%).

Accurate information about marsquake locations is crucial for understanding the tectonic activity, subsurface structures, and dynamics of Mars. We designed a varying‐parameter scheme for polarization analysis to determine the back‐azimuths of marsquakes. For two Martian meteorite impact events with ground‐truth locations known from orbital images, our scheme yields back‐azimuths that are ∼5° and ∼14° closer to the true values than those reported previously, demonstrating our method's advantages in constraining back‐azimuths. We applied this method to determine the back‐azimuths of 44 Low Frequency marsquakes and 39 were reliably relocated. Nearly half of these marsquakes occur in Cerberus Fossae, while the rest are broadly distributed, including along the dichotomy boundary and within the northern lowlands and southern highlands. Although further studies are required to understand the mechanisms of these marsquakes, the widespread seismicity implies that present‐day Mars, especially the ancient southern highlands, is more tectonically active than previously thought. Plain Language Summary Identifying seismic activity on Mars is crucial for advancing our understanding of the planet's present‐day properties and tectonic processes. From February 2019 to December 2022, the InSight seismograph captured nearly one hundred Low Frequency marsquakes. As these marsquakes have similar ground vibration characteristics to tectonic earthquakes, they are important to understand tectonic‐related activities on Mars. However, there is only a single seismograph on Mars, and some of the data for Low Frequency marsquakes are noisy, making it challenging to precisely determine their locations. To improve the accuracy of marsquake locations, we devised a scheme using sliding time and frequency windows to effectively constrain the orientation of marsquakes relative to the seismograph. With this method, we successfully relocated 39 Low Frequency marsquakes. Our new findings indicate that a significant portion, approximately half, of these marsquakes are concentrated in the Cerberus Fossae region, while the remaining events are distributed across various tectonic units. Interestingly, we have also identified marsquakes within the ancient southern highlands, an area that has previously had limited reports of seismic activity. Although the origin of marsquakes may differ from region to region, the widespread distribution of marsquakes suggests that Mars is more tectonically active than previously thought. Key Points The varying‐parameter polarization analysis scheme can effectively improve the accuracy of back‐azimuth estimates for marsquakes Several additional Low Frequency marsquakes have been identified within the southern highlands of Mars The widespread Martian seismicity implies that Mars is more tectonically active than previously thought

Data analysis methods have scarcely kept pace with the rapid increase in Earth observations, spurring the development of novel algorithms, storage methods, and computational techniques. For scientists interested in Mars, the problem is always the same: there is simultaneously never enough of the right data and an overwhelming amount of data in total. Finding sufficient data needles in a haystack to test a hypothesis requires hours of manual data screening, and more needles and hay are added constantly. To date, the vast majority of Martian research has been focused on either one-off local/regional studies or on hugely time-consuming manual global studies. Machine learning in its numerous forms can be helpful for future such work. Machine learning has the potential to help map and classify a large variety of both features and properties on the surface of Mars and to aid in the planning and execution of future missions. Here, we outline the current extent of machine learning as applied to Mars, summarize why machine learning should be an important tool for planetary geomorphology in particular, and suggest numerous research avenues and funding priorities for future efforts. We conclude that: (1) moving toward methods that require less human input (i.e., self- or semi-supervised) is an important paradigm shift for Martian applications, (2) new robust methods using generative adversarial networks to generate synthetic high-resolution digital terrain models represent an exciting new avenue for Martian geomorphologists, (3) more effort and money must be directed toward developing standardized datasets and benchmark tests, and (4) the community needs a large-scale, generalized, and programmatically accessible geographic information system (GIS).