Preprints
Filtering by Subject: Physical Sciences and Mathematics
Gravitational field calculation in spherical coordinates using variable densities in depth
Published: 2019-06-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a new methodology to compute the gravitational fields generated by tesseroids (spherical prisms) whose density varies with depth according to an arbitrary continuous function. It approximates the gravitational fields through the Gauss-Legendre Quadrature along with two discretization algorithms that automatically control its accuracy by adaptively dividing the tesseroid into smaller [...]
Areal parameter estimates from multiple datasets
Published: 2019-06-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A wide range of methods exist for interpolation between spatially distributed points drawn from a single population. Yet often multiple datasets are available with differing distribution, character and reliability. A simple scheme is introduced to allow the fusion of multiple datasets. Each dataset is assigned an a priori spatial influence zone around each point and a relative weight based on its [...]
Modification of fumarolic gases by the ice-covered edifice of Erebus volcano, Antarctica
Published: 2019-06-07
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
The chemistry of gases measured in ice caves and from warm geothermal ground at Erebus volcano, Antarctica, show that gas emissions are dominated by air, with varying amounts of added volcanic CO2. This suggests widespread circulation of air through the volcanic edifice, as well as spatially or temporally varying contributions from magmatic degassing. The resulting gases are further modified by [...]
Distributed sensing of earthquakes and ocean-solid Earth interactions on seafloor telecom cables
Published: 2019-06-07
Subjects: Earth Sciences, Environmental Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Physics
Two thirds of the surface of our planet are covered by water and are still poorly instrumented, which has prevented the earth science community from addressing numerous key scientific questions. The potential to leverage the existing fiber optic seafloor telecom cables that criss-cross the oceans, by turning them into dense arrays of seismo-acoustic sensors, remains to be evaluated. Here, we [...]
Understanding Low Cloud Mesoscale Morphology with an Information Maximizing Generative Adversarial Network
Published: 2019-06-05
Subjects: Artificial Intelligence and Robotics, Atmospheric Sciences, Computer Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Generative adversarial networks (GANs) are a class of machine learning algorithms with two neural networks, one generator and one discriminator, playing adversarial games with each other. Information maximizing GANs (InfoGANs) is a particular GAN type that tries to maximize mutual information between a subset of latent variables and generated samples, thereby establishing a mapping between the [...]
Decadal land-use/land-cover and land surface temperature change in Dubai and implications on the urban heat island effect: A preliminary assessment
Published: 2019-06-05
Subjects: Environmental Sciences, Environmental Studies, Geographic Information Sciences, Geography, International and Area Studies, Near and Middle Eastern Studies, Other Environmental Sciences, Physical and Environmental Geography, Physical Sciences and Mathematics, Remote Sensing, Social and Behavioral Sciences
The emirate of Dubai is the most populous and most developed of the seven emirates that comprise the United Arab Emirates. By the end of the 20th century, the emirate had shifted its economy from being primarily petroleum-based to a focus on tourism and financial services. The emirate’s capital, also named Dubai, has been growing at a rapid pace; the population in 1999 was 862,000 inhabitants, [...]
A new method for in-situ measurement of the erosion threshold of river channels
Published: 2019-06-05
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
The vast majority of alluvial deposits have some degree of cohesion, typically due to the presence of clays and/or organic matter. Determining the threshold fluid shear stress necessary to entrain these sediments is essential for predicting erosion rates and morphodynamics of rivers, tidal channels, and coasts. Cohesive sediments present a greater challenge than non-cohesive sand and gravel beds [...]
Lower crustal earthquakes in the East African Rift System: Insights from frictional properties of rock samples from the Malawi rift
Published: 2019-06-05
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Earthquakes in the southern part of the East African Rift System (EARS) occur at depths up to 45 km in the lower crust, unusually deep for an extensional regime. Typically, earthquakes in continental crust nucleate at temperatures less than 350°C, the temperature at which crystal plastic creep in quartz becomes efficient, corresponding to a depth of ~15 km with an average continental geothermal [...]
A Stratigraphic Approach to Inferring Depositional Ages From Detrital Geochronology Data
Published: 2019-06-04
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
With the increasing use of detrital geochronology data for provenance analyses, we have also developed new constraints on the age of otherwise undateable sedimentary deposits. Because a deposit can be no older than its youngest mineral constituent, the youngest defensible detrital mineral age defines the maximum depositional age of the sampled bed. Defining the youngest `defensible age in the [...]
Amplified Last-Glacial-Maximum response of Chandra valley (western Himalaya) glaciers
Published: 2019-06-03
Subjects: Earth Sciences, Geomorphology, Glaciology, Physical Sciences and Mathematics
Geomorphological evidence suggests a subdued response of Himalayan glaciers during the Last Glacial Maximum (LGM), with relatively minor advances (~10 km) reported in several glacierised valleys across the region. This supports the hypothesis that a weakened Indian summer monsoon during the LGM largely counterbalanced the effects of a colder climate on Himalayan glaciers. In contrast, a recently [...]
Characterising Land Cover Change in Brunei Darussalam’s Capital District
Published: 2019-06-03
Subjects: Computer Sciences, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Natural Resources and Conservation, Physical Sciences and Mathematics
In fast-developing regions, like Southeast-Asia, monitoring urban areas presents a challenge given the lack of publicly available data. This is an issue that precludes the nuances of a citys growth and undermines the way land-use is considered with respect to planning. The issue of data availability is very much present in the small nation of Brunei. Little is still known about the spatiotemporal [...]
Physically consistent modeling of dike induced deformation and seismicity: Application to the 2014 Bárðarbunga dike, Iceland
Published: 2019-06-03
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Dike intrusions are often associated with surface deformation and propagating swarms of earthquakes. These are understood to be manifestations of the same underlying physical process, although rarely modeled as such. We construct a physics-based model of the 2014 B\ar{\dh}arbunga dike, by far the best observed large dike ($> 0.5$ km$^3$) to date. We constrain the background stress state [...]
Glacier area and the variability of glacier change
Published: 2019-05-31
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
This is the preprint of a letter that is under review in the Journal of Glaciology. The abstract is as follows: Large-scale remote-sensing data on ice loss in the Himalaya and other glacierised regions indicate that the differences in glacier area do not significantly influence the glacier-to-glacier variability of the thinning rate. An analysis of the available data from several regions across [...]
Estimation of the total sub-debris ablation from point-scale ablation data on a debris-covered glacier
Published: 2019-05-31
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
This is the preprint of an article that is under review in the Journal of Glaciology. The abstract is as follows: Glaciological mass balance is computed from point-scale field data at a few ablation stakes that are regressed as a function of elevation, and averaged over the area-elevation distribution of the glacier. This method is contingent on a tight control of elevation on local ablation. On [...]
The glacial express
Published: 2019-05-31
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics
Glacial calcium carbonate (CaCO3) shells are larger than interglacial CaCO3 shells. My research explores the consequences of this size difference. Because larger CaCO3 shells sink faster and dissolve more slowly than smaller CaCO3 shells, larger glacial shells underwent less dissolution than smaller interglacial shells. The resulting CaCO3 transport efficiency increase, coupled with observations [...]