Preprints
Filtering by Subject: Physical Sciences and Mathematics
A deep-learning estimate of the decadal trends in the Southern Ocean carbon storage
Published: 2021-04-20
Subjects: Atmospheric Sciences, Biogeochemistry, Climate, Earth Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Uptake of atmospheric carbon by the ocean, especially at high latitudes, plays an important role in offsetting anthropogenic emissions. At the surface of the Southern Ocean south of 30◦S, the ocean carbon uptake, which had been weakening in 1990s, strengthened in the 2000s. However, sparseness of in-situ measurements in the interior make it difficult to compute changes in carbon storage below [...]
Water acceleration in a supraglacial channel predicts locations of step-pool sequence formation
Published: 2021-04-20
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Supraglacial channels constitute an important part of the glacial hydrological system, both by influencing surface energy exchange as well as routing meltwater to eventually feed en- and subglacial drainage systems. Subglacial systems have received considerable scientific interest, but specific studies of supraglacial channels are sparse. This limited scientific understanding represents a missing [...]
The Mid-Lithospheric Discontinuity caused by channel flow in the cratonic lithosphere
Published: 2021-04-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Stable cratons with a thick (> 200 km) and cold lithosphere form rheologically strong plates that move atop a ductile asthenospheric mantle. Various types of seismic observations show the presence of a potentially rheologically weak zone at depths of ca. 80 – 150 km termed the Mid-Lithosphere Discontinuity (MLD). While various mechanisms may explain the MLD, the dynamic processes leading to the [...]
Revision of thelodonts, acanthodians, conodonts, and the depositional environments in the Burgen outlier (Ludlow, Silurian) of Gotland, Sweden
Published: 2021-04-20
Subjects: Biodiversity, Earth Sciences, Ecology and Evolutionary Biology, Life Sciences, Physical Sciences and Mathematics
Ludfordian strata exposed in the Burgen outlier in eastern Gotland record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and [...]
The Effect of Ti on Ca-pv and Mg-pv phase stability
Published: 2021-04-20
Subjects: Physical Sciences and Mathematics
Magnesium silicate perovskite in the form of bridgmanite (bdg) and Calcium silicate perovskite (Ca-pv) have similar chemical structures and may mix into a single perovskite phase in the lower mantle which would have profound effects on many seismic properties. While we have previously found that this is unlikely to occur in pure bdg and ca-pv in this paper we examine whether phase mixing can be [...]
Particulate PhozzyLogic Index for policy makers—an index for a more accurate and transparent identification of critical source areas
Published: 2021-04-20
Subjects: Environmental Sciences, Physical Sciences and Mathematics, Water Resource Management
This study presents an algorithm for the allocation of particulate phosphorus (PP) loads entering surface waters to their sources of origin, which is a basic requirement for the identification of critical PP source areas and in turn a cost-effective implementation of mitigation measures. Furthermore, it conducts a sensitivity analysis determining the impacts of storm drains, discharge frequencies [...]
Reactivation Potential of Intraplate Faults in the Western Quebec Seismic Zone, Eastern Canada
Published: 2021-04-19
Subjects: Earth Sciences, Physical Sciences and Mathematics
The intraplate western Quebec seismic Zone (WQSZ) in eastern Canada experiences moderate seismicity that mainly results from reactivation of inherited structures under the present-day, NE-striking regional stress field and, possibly to a minor extent, through stress perturbations in response to glacio-isostatic adjustments. This work comprises the first numerical stress simulation-based study [...]
Comparison of Machine Learning Approaches for Tsunami Forecasting from Sparse Observations
Published: 2021-04-18
Subjects: Physical Sciences and Mathematics
We have explored various different machine learning (ML) approaches for forecasting tsunami amplitudes at a set of forecast points, based on hypothetical short-time observations at one or more observation points. As a case study, we chose an observation point near the entrance of the Strait of Juan de Fuca, and two forecast points in the Salish Sea, one in Discovery Bay and the other in Admiralty [...]
The effect of water and pressure on fabric development in olivine
Published: 2021-04-17
Subjects: Physical Sciences and Mathematics
Water has a very strong effect on both the strength and fabric development of forsterite but the mechanism of this effect is unclear. In the paper we use Density Functional Theory Peierls-Nabarro modelling to examine the effect of water on the Peierls stress of different forsterite slip systems. We find that water in Mg vacancies will weaken [100](010) slip and thus produce A fabrics while [...]
Controls on the distribution of hydrous defects in forsterite from a thermodynamic model
Published: 2021-04-15
Subjects: Physical Sciences and Mathematics
The distribution of hydrogen across different crystallographic sites and point defects in forsterite is important because it determines how many properties, such as rheology, conductivity, diffusion and elemental partitioning are affected by water. In this study we use lattice dynamics and Density Functional Theory (DFT) to build a thermodynamic model of H-bearing defects that incorporates both [...]
Source region geochemistry from unmixing downstream sedimentary elemental compositions
Published: 2021-04-15
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The geochemistry of river sediments is routinely used to obtain information about geologic and environmental processes occurring upstream. For example, downstream samples are used to constrain chemical weathering and physical erosion rates upstream, as well as the locations of mineral deposits or contaminant sources. Previous work has shown that, by assuming conservative mixing, the geochemistry [...]
Structure and Stress Field of the Lithosphere between Pamir and Tarim
Published: 2021-04-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The Pamir plateau protrudes ~300 km between the Tajik- and Tarim-basin lithosphere of Central Asia. Whether its salient location and shape are caused by forceful indentation of a promontory of Indian mantle lithosphere is debated. We present a new local-seismicity and focal-mechanism catalog, and a P-wave velocity model of the eastern part of the collision system. The data suggest a [...]
Microstructural differences between naturally-deposited and laboratory beach sands
Published: 2021-04-14
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Geotechnical Engineering, Physical Sciences and Mathematics, Sedimentology
The orientation of and contacts between grains of sand reflect the processes that deposit the sands. Grain orientation and contact geometry also influence mechanical properties. Quantifying and understanding sand microstructure thus provide an opportunity to understand depositional processes better and connect microstructure and macroscopic properties. We compare naturally-deposited beach sands [...]
Evaluation of satellite precipitation products for water allocation studies in the Sio-Malaba-Malakisi River Basin of East Africa
Published: 2021-04-14
Subjects: Physical Sciences and Mathematics
Study region: Sio Malaba Malakisi river basin, East Africa. Study Focus: Poor rain-gauge density is a limitation to comprehensive hydrological studies in Sub-Saharan Africa. Consequently, Satellite precipitation products (SPPs) provide an alternative source of data for possible use in hydrological modelling. However, there is need to test their reliabilities across varied hydro-climatic and [...]
Probing the DPRK nuclear test-site down to low seismic magnitude
Published: 2021-04-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
On 3 September 2017, the Democratic People’s Republic of Korea (DPRK) carried out its sixth declared underground nuclear test (NK6) at the Punggye‐ri test site. With body‐wave magnitude 6.1, this explosion was significantly larger than any of the previous five explosions, and it has been followed by numerous smaller seismic events. The explosion generated seismic waves dominated by significantly [...]