Preprints
Filtering by Subject: Physical Sciences and Mathematics
Numerical modeling of Earth's dynamic surface: a community approach
Published: 2021-02-14
Subjects: Civil and Environmental Engineering, Computer Sciences, Earth Sciences, Engineering, Environmental Engineering, Environmental Sciences, Geology, Geomorphology, Glaciology, Hydrology, Numerical Analysis and Scientific Computing, Other Environmental Sciences, Physical Sciences and Mathematics, Sedimentology, Soil Science, Stratigraphy
Computational modelling occupies a unique niche in Earth environmental sciences. Models serve not just as scientific technology and infrastructure, but also as digital containers of the scientific community's understanding of the natural world. As this understanding improves, so too must the associated software. This dual nature---models as both infrastructure and hypotheses---means that [...]
Two-sided turbulent surface layer parameterizations for computing air-sea fluxes
Published: 2021-02-13
Subjects: Physical Sciences and Mathematics
Standard methods for determining air – sea fluxes typically rely on bulk algorithms set in the frame of Monin-Obukhov stability theory (MOST), using ocean surface fields and atmosphere near-surface fields. In the context of coupled ocean – atmosphere simulations, the shallowest ocean vertical level is usually used as bulk input and by default, the turbulent closure is one-sided: it extrapolates [...]
High-resolution observations of the North Pacific transition layer from a Lagrangian float
Published: 2021-02-11
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
A crucial region of the ocean surface boundary layer (OSBL) is the strongly-sheared and -stratified transition layer (TL) separating the mixed layer from the upper pycnocline, where a diverse range of waves and instabilities are possible. Previous work suggests that these different waves and instabilities will lead to different OSBL behaviours. Therefore, understanding which physical processes [...]
Using Landsat and Sentinel Imagery to Monitor Alfalfa and Grass Pastures in Western Colorado
Published: 2021-02-10
Subjects: Engineering, Physical Sciences and Mathematics
Crop phenology of alfalfa and grass pasture fields on the western slope of Colorado, USA, was tracked using an NDVI time series derived from Landsat 7 (ETM+), Landsat 8 (OLI) and Sentinel 2a MSI to obtain high temporal frequency information of crop growth stages. These perennial pastures, which occupy a majority of irrigated land in the region and typically have more than one growing/cutting [...]
Improving the Robustness of the Comparison Model Method for the Identification of Hydraulic Transmissivities
Published: 2021-02-10
Subjects: Engineering, Physical Sciences and Mathematics
The Comparison Model Method (CMM) is a relatively simple and computationally efficient direct method for the identification of the transmissivity of a confined aquifer by solution of an inverse problem. However, it suffers some of the classical drawbacks related to ill-posedness and ill-conditioning of inverse methods. Effectiveness of the CMM can be improved by some approaches. First of all, the [...]
Creating and Promoting Gender Equity and Diversity in Professional Geological Societies: A Focus on AAPG
Published: 2021-02-10
Subjects: Education, Physical Sciences and Mathematics, Social and Behavioral Sciences
When professional organizations allow gender inequity to persist, they continually lose talented, valuable individuals who enrich and lead their groups and drive innovation. This paper presents an analysis of membership data and ways in which member contributions are recognized by the American Association of Petroleum Geologists (AAPG) between 2017-2020, in relation to gender. These are compared [...]
Impact of wave-vortical interactions on oceanic submesoscale lateral dispersion
Published: 2021-02-09
Subjects: Physical Sciences and Mathematics
Submesoscale lateral transport of a passive tracer and Lagrangian particles in the ocean is investigated by means of numerical simulations with intermediate models. Using a projection technique, the models are formulated in terms of wave-mode and vortical-mode nonlinear interactions, and they range in complexity from full Boussinesq to waves-only and vortical-modes-only models. We find that, on [...]
Smooth crustal velocity models cause a depletion of high-frequency ground motions on soil in 2-D dynamic rupture simulations
Published: 2021-02-04
Subjects: Physical Sciences and Mathematics
A depletion of high-frequency ground motions on soil sites has been observed in recent large earthquakes and is often attributed to the nonlinear soil response. Here we show that the reduced amplitudes of high-frequency horizontal-to-vertical spectral ratios on soil can also be caused by a smooth crustal velocity model with low shear wave velocities underneath soil sites. We calculate near-fault [...]
Audible acoustics from low-magnitude fluid-induced earthquakes in Finland
Published: 2021-02-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquakes are frequently accompanied by public reports of audible low-frequency noises. In 2018, public reports of booms or thunder-like noises were linked to induced earthquakes during a Engineered Geothermal System project in the Helsinki Metropolitan area. In response, two microphone arrays were deployed to record and study these acoustic signals while stimulation at the drill site [...]
Distilling the Mechanism for the Madden-Julian Oscillation into a Simple Translating Structure
Published: 2021-02-02
Subjects: Physical Sciences and Mathematics
This paper presents a minimal model of the Madden--Julian Oscillation (MJO), isolating a robust mechanism that leads to the observed characteristic pattern and eastward propagation. A localized heat source due to condensation at the equator leads to a Gill-like pattern in the geopotential, which in turn induces moisture convergence and further condensation. Over a wide range of parameters [...]
Post-2018 caldera collapse re-inflation uniquely constrains Kīlauea's magmatic system
Published: 2021-02-02
Subjects: Physical Sciences and Mathematics
From August 2018 to May 2019, Kīlauea’s summit exhibited unique, simultaneous, inflation and deflation, apparent in both GPS time series and Small Baseline Subset (SBAS) derived cumulative InSAR displacement maps. This deformation pattern provides clear evidence that Halema`uma`u (HMM) and South Caldera (SC) are distinct reservoirs. Post-collapse inflation of the East Rift Zone (ERZ), as captured [...]
Dynamical attribution of North Atlantic interdecadal predictability to oceanic and atmospheric turbulence under realistic and optimal stochastic forcing
Published: 2021-02-01
Subjects: Climate, Environmental Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Unpredictable variations in the ocean originate from both external atmospheric forcing and chaotic processes internal to the ocean itself, and are a crucial sink of predictability on interdecadal timescales. In a global ocean model, we present i.) an optimisation framework to compute the most efficient noise patterns to generate uncertainty and ii.) a uniquely inexpensive, dynamical method for [...]
Temperature and water depth effects on brGDGT distributions in sub-alpine lakes of mid-latitude North America
Published: 2021-01-31
Subjects: Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics
Branched glycerol dialkyl glycerol tetraethers (brGDGTs) in lake sediments are increasingly being used to reconstruct past temperatures. However, recent studies suggest that brGDGT distributions and concentrations vary with lake size and environmental conditions such as seasonality and its effects on water column temperature and chemistry. To test their use as a paleothermometer in high-altitude [...]
Shear wave velocity structure beneath North-Western Himalaya and adjoining areas
Published: 2021-01-30
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Shear wave velocity structure, together with Moho depths have been estimated in northwestern Himalaya, Hindu Kush and the Pamirs at a potential resolution of 0.5×0.5 degrees and at 1×1 degrees in the surrounding area, by inverting fundamental mode Rayleigh wave group velocities calculated from regional earthquake (Δ ≤ 2500 km) data, and also from their joint inversions with teleseismic receiver [...]
Rift Interaction Zones and the Stages of Rift Linkage in Active Segmented Continental Rift Systems
Published: 2021-01-30
Subjects: Physical Sciences and Mathematics
Although much is known about the interaction of faulting and sedimentation within the basins of active segmented continental rift systems, little is known about these processes within the interaction zones of varying geometries that separate the young interacting segments. We address this problem in the humid, magma-poor juvenile western branch of the East African Rift System (WB-EARS). First, we [...]