Preprints
There are 5476 Preprints listed.
Origin, transport, accumulation of methane in sedimentary basins revisited
Published: 2022-10-02
Subjects: Physical Sciences and Mathematics
The current widely accepted models for generation of methane by thermal cracking of oil and by bacterial fermentation have several serious inconsistencies. Experiments show that high-temperature pyrolysis of liquid (C6+) hydrocarbons does not produce methane even if hydrogen is added to the feed, and condensate, which is generally assumed to be the direct precursor to methane, generally amounts [...]
Loop Current attenuation after the Mid-Pleistocene Transition contributes to Northern hemisphere cooling
Published: 2022-10-01
Subjects: Earth Sciences, Environmental Sciences, Oceanography and Atmospheric Sciences and Meteorology
The beginning of the Mid-Pleistocene Transition (MPT) ~920 ka BP marked the expansion of northern hemisphere ice shields and caused a significant climate change in NW Europe. The MPT ended with the establishment of the 100 kyr ice age cyclicity at ~640 ka BP, due to orbital eccentricity changes. Previous studies explained the northern hemisphere cooling by cooling of sea-surface temperatures, [...]
Geochemical mapping by unmixing alluvial sediments: An example from northern Australia
Published: 2022-10-01
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geochemistry, Geomorphology, Natural Resource Economics, Sedimentology, Soil Science, Water Resource Management
Alluvial sediments have long been used in geochemical surveys as their compositions are assumed to be representative of areas upstream. Overbank and floodplain sediments, in particular, are increasingly used for regional to continental-scale geochemical mapping. However, during downstream transport, sediments from heterogeneous source regions are carried away from their source regions and mixed. [...]
Modeling Stratospheric Polar Vortex Variation and Identifying Vortex Extremes Using Explainable Machine Learning
Published: 2022-10-01
Subjects: Physical Sciences and Mathematics
The winter stratospheric polar vortex (SPV) exhibits considerable variability in magnitude and structure, which can result in extreme SPV events. These extremes can subsequently influence weather in the troposphere from weeks to months and thus are important sources of surface predictability. However, the predictability of the SPV extreme events is limited to 1-2 weeks in state-of-the-art [...]
Global groundwater warming
Published: 2022-10-01
Subjects: Earth Sciences, Physical Sciences and Mathematics
Aquifers contain the largest store of unfrozen freshwater, making groundwater critical for life on Earth. Groundwater temperatures infl uence stream thermal regimes, groundwater-dependent ecosystems, aquatic biogeochemical processes, water quality, and the geothermal potential. Yet little is known about how groundwater responds to surface warming across spatial and temporal scales. We simulate [...]
Impact of stress regime change on the permeability of a naturally fractured carbonate buildup (Latemar, The Dolomites, Northern Italy)
Published: 2022-09-30
Subjects: Earth Sciences
Changing stress regimes control fracture network geometry and influence porosity and permeability in carbonate reservoirs. Using outcrop data analysis and a displacement-based linear elastic finite element method, we investigate the impact of stress-regime change on fracture network permeability. The model is based on fracture networks, specifically fracture sub-structures. The Latemar, [...]
Characteristics of Dust Storms Generated by Trapped Waves in the Lee of Mountains
Published: 2022-09-29
Subjects: Atmospheric Sciences, Climate, Meteorology, Oceanography and Atmospheric Sciences and Meteorology
Dust storms are ubiquitous in the Earth's atmosphere, yet the physical processes underlying dust emission and subsequent transport are not always understood, in-part due to the wide variety of meteorological processes that can generate high winds and dust. Here we use in-situ measurements and numerical modeling to demonstrate that vertically trapped atmospheric waves generated by air flowing over [...]
The Asymmetric Distribution of Rainfall Frequency and Amounts in India
Published: 2022-09-29
Subjects: Civil and Environmental Engineering, Hydraulic Engineering
Studies of rainfall usually focus on the total amount precipitating throughout a certain period. Compared to rain rates associated with extreme events, the rain rates associated with the most frequent events is understudied. In this study, the characteristics of daily precipitation in India are explored using two metrics - rain frequency peak (the most frequent non-zero rain rate) and rain amount [...]
A critical review of the sedimentary record of the `Millennium Eruption' of Changbaishan/Paektu-san volcano
Published: 2022-09-29
Subjects: Education
The `Millennium Eruption’ of Changbaishan/Paektu-san Volcano, situated today on border between the People's Republic of China and Democratic People's Republic of Korea, ranks as one of the largest eruptions of the Common Era. Dated to 946 CE, its tephra deposits represent a critical marker spanning terrestrial and marine archives, as well as the glacial record of Greenland. Its geographically [...]
Comparative study of alteration sequences in pegmatitic aluminium phosphates
Published: 2022-09-29
Subjects: Earth Sciences, Geochemistry, Geology, Mineral Physics, Other Earth Sciences
Aluminium phosphates are mineral phases commonly occurring in rare-element pegmatites that record initial magmatic crystallization, metasomatic and hydrothermal replacements and precipitation and low-temperature alteration. Here we perform a comparative mineralogical study between several localities to assess similarities and variations in these parageneses and establish a general alteration [...]
Tsunami Early Warning from Global Navigation Satellite System Data using Convolutional Neural Networks
Published: 2022-09-29
Subjects: Earth Sciences, Geophysics and Seismology, Hydrology, Oceanography
We investigate the potential of using Global Navigation Satellite System (GNSS) observations to directly forecast full tsunami waveforms in real time. We train convolutional neural networks (CNNs) to use less than 9 minutes of GNSS data to forecast the full tsunami waveforms over 6 hours at select locations, and obtain accurate forecasts on a test dataset. Our training and test data consists of [...]
Post-salt magmatism in the Campos Basin, offshore SE Brazil: style, distribution, and relationship to salt tectonics
Published: 2022-09-28
Subjects: Physical Sciences and Mathematics
Substantial magmatism occurred during the development of the marginal basins of the central and southern South Atlantic. Situated on the Brazilian side of the central segment, the Campos and Santos basin represent a transitional margin, located between the magma-rich margin in the north and the magma-poor margin in the south. In addition to magmatism associated with the initiation of continental [...]
Taxon cycles in Neotropical mangroves
Published: 2022-09-27
Subjects: Life Sciences
The concept of taxon cycle involves successive range expansions and contractions over time through which a species can maintain indefinitely its core distribution. Otherwise, it becomes extinct. A typical taxon cycle can be subdivided into four stages: (I) expansion, (II) population differentiation, (III) local extinction and incipient speciation (eventually initiating a new cycle), and (IV) [...]
STEEP: a remotely-sensed energy balance model for evapotranspiration estimation in seasonally dry tropical forests
Published: 2022-09-27
Subjects: Hydrology, Meteorology
Improvement of evapotranspiration (ET) estimates using remote sensing (RS) products based on multispectral and thermal sensors has been a breakthrough in hydrological research. In large-scale applications, methods that use the approach of RS-based surface energy balance (SEB) models often rely on oversimplifications. The use of these models for Seasonally Dry Tropical Forests (SDTF) has been [...]
Eocene/Oligocene global disruption and the revolution of Caribbean mangroves
Published: 2022-09-27
Subjects: Life Sciences
In a recent paper, the author demonstrated that, in contrast with the prevailing view of eventual gradual regional differentiation from a hypothetical Cretaceous pantropical mangrove belt around the Tethys Sea, the Caribbean mangroves originated de novo in the Eocene after the evolutionary appearance of the first mangrove-forming tree species known for the region, the ancestor of the extant [...]