Preprints
Filtering by Subject: Physical Sciences and Mathematics
Anatomy of exhumed river-channel belts: Bedform- to belt-scale kinematics of the Ruby Ranch Member, Cretaceous Cedar Mountain Formation, Utah, USA
Published: 2019-08-29
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of paleoriver kinematics, depositional setting, and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barform strata. Dune and bar strata, channel planform [...]
Accounting for training data error in machine learning applied to Earth observations
Published: 2019-08-29
Subjects: Earth Sciences, Engineering, Environmental Monitoring, Environmental Sciences, Life Sciences, Physical Sciences and Mathematics
Remote sensing, or Earth Observation (EO), is increasingly used to understand Earth system dynamics and create continuous and categorical maps of biophysical properties and land cover, especially based on recent advances in machine learning (ML). ML models typically require large, spatially explicit training datasets to make accurate predictions. Training data (TD) are typically generated by [...]
Observed and modelled tidal bar sedimentology reveals preservation bias against mud in estuarine stratigraphy
Published: 2019-08-29
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
Mud plays a pivotal role in estuarine ecology and morphology. However, field data on the lateral and vertical depositional record of mud is rare. Furthermore, numerical morphodynamic models often ignore mud due to long computational times and implications of mixed depositional processes. This study aims to understand the spatial distribution, formative conditions, and preservation of mud deposits [...]
Considering the role of adaptive evolution in models of the ocean and climate system
Published: 2019-08-29
Subjects: Earth Sciences, Ecology and Evolutionary Biology, Life Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Numerical models have been highly successful in simulating global carbon and nutrient cycles in today’s ocean, together with observed spatial and temporal patterns of chlorophyll and plankton biomass at the surface. With this success has come some confidence in projecting the century-scale response to continuing anthropogenic warming. There is also increasing interest in using such models to [...]
Solar signals in observation indeed implied enhanced predictability since 1977
Published: 2019-08-27
Subjects: Climate, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
This is a Correspondence submitted to Nature GeoScience following the undermentioned paper: Gabriel Chiodo, Jessica Oehrlein, Lorenzo M. Polvani, John C. Fyfe & Anne K. Smith, Insignificant influence of 11-year solar cycle on the North Atlantic Oscillation, Nature Geoscience, volume 12, pages 94–99 (2019). It is a non-peer reviewed preprint.
Fracture Mechanical Properties of Damaged and Hydrothermally Altered Rocks, Dixie Valley - Stillwater Fault Zone, Nevada, USA
Published: 2019-08-27
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
An edited version of this paper was published by AGU. Copyright (2019) American Geophysical Union. Callahan, O. A., Eichhubl, P., Olson, J. E., & Davatzes, N. C. (2019). Fracture Mechanical Properties of Damaged and Hydrothermally Altered Rocks, Dixie Valley‐Stillwater Fault Zone, Nevada, USA. Journal of Geophysical Research: Solid Earth, 124(4), 4069-4090. [...]
Towards Improved Predictions in Ungauged Basins: Exploiting the Power of Machine Learning
Published: 2019-08-26
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Long Short-Term Memory (LSTM) networks offer unprecedented accuracy for prediction in ungauged basins. We trained and tested an LSTM on the CAMELS basins (approximately 30 years of daily rainfall/runoff data from 531 catchments in the US of sizes ranging from 4 km² to 2,000 km²) using k-fold validation, so that predictions were made in basins that supplied no training data. This effectively [...]
Cohesive-Zone Effects in Hydraulic Fracture Propagation
Published: 2019-08-22
Subjects: Earth Sciences, Engineering, Engineering Mechanics, Engineering Science and Materials, Environmental Sciences, Geophysics and Seismology, Oil, Gas, and Energy, Physical Sciences and Mathematics
Hydraulic fracture presents an interesting case of crack elasticity and fracture propagation non-linearly coupled to fluid flow. Hydraulic fracture (HF) is often modeled using the Linear Elastic Fracture Mechan- ics (LEFM), which assumes that the damaged zone associated with the rock breakage near the advancing fracture front is small compared to the lengthscales of other physical processes [...]
Accelerating Numerical Wave Propagation by Wavefield Adapted Meshes, Part II: Full-Waveform Inversion
Published: 2019-08-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a novel full-waveform inversion approach which can reduce the computational cost by up to an order of magnitude compared to conventional approaches, provided that variations in medium properties are sufficiently smooth. Our method is based on the usage of wavefield-adapted meshes which accelerate the forward and adjoint wavefield simulations. By adapting the mesh to the expected [...]
Communicating with public audiences about the geological subsurface: thinking inside the box.
Published: 2019-08-21
Subjects: Earth Sciences, Physical Sciences and Mathematics, Social and Behavioral Sciences
Community concerns over resource extraction and public anxieties about insertion of waters and waste are creating a growing societal unease about geological exploitation of the subsurface. Addressing these emergent areas of socially contested subsurface geoscience is difficult for many academic and industrial geologists, not least because translating unfamiliar concepts of the geological [...]
Collapse of Eurasian ice sheets 14,600 years ago was a major source of global Meltwater Pulse 1a
Published: 2019-08-21
Subjects: Climate, Earth Sciences, Environmental Sciences, Geology, Glaciology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Rapid sea-level rise caused by the collapse of large ice sheets is a global threat to human societies. In the last deglacial period, the rate of global sea-level rise peaked at more than 4 cm/yr during Meltwater Pulse 1a, which coincided with the abrupt Bølling warming event 14,650 yr ago. However, the sources of the meltwater have proven elusive, and the contribution from Eurasian ice sheets has [...]
What Fractionates Oxygen Isotopes During Respiration? Insights from Multiple Isotopologues and Theory
Published: 2019-08-21
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics
The precise mass dependence of respiratory O2 consumption underpins the “oxygen triple-isotope” approach to quantifying gross primary productivity in modern and ancient environments. Yet, the physical-chemical origins of the key 18O/16O and 17O/16O covariations observed during respiration have not been tied to theory; thus the approach remains empirical. First-principles calculations on enzyme [...]
The anelasticity of zinc and its implications for the Earth’s inner core
Published: 2019-08-21
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics
The Earth’s inner core exhibits significant anisotropy in both seismic velocity and attenuation as well as hemispherical and depth variations. These observations point to an inner core that is both complex and dynamic. However, interpretation of these observations without knowledge of the attenuation processes active in the inner-core is difficult. To address this we have used zinc, as a [...]
Quantifying Eulerian Eddy Leakiness in An Idealized Model
Published: 2019-08-21
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
An idealized eddy-resolving ocean basin, closely resembling the North Pacific ocean, is simulated using MITgcm. We identify rotationally coherent Lagrangian vortices (RCLVs) and sea surface height (SSH) eddies based on the Lagrangian and Eulerian framework, respectively. General statistical results show that RCLVs have a much smaller coherent core than SSH eddies with the ratio of radius is about [...]
Shifting velocity of temperature extremes under climate change
Published: 2019-08-19
Subjects: Climate, Environmental Indicators and Impact Assessment, Environmental Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Rapid changes in climatic conditions threaten both socioeconomic and ecological systems, as these might not be able to adapt or to migrate at the same pace as that of global warming. In particular, an increase of weather and climate extremes can lead to increased stress on human and natural systems, and a tendency for serious adverse effects. Relying on the EURO-CORDEX simulations, we compare the [...]