# Preprints

Filtering by Subject: Applied Mathematics

## A study of extreme water waves using a hierarchy of models based on potential-flow theory

**Published**: 2023-12-02

**Subjects**: Applied Mathematics, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Partial Differential Equations, Physical Sciences and Mathematics

The formation of extreme waves arising from the interaction of three line-solitons with equal far-field amplitudes is examined through a hierarchy of water-wave models. The Kadomtsev-Petviashvili equation (KPE) is first used to prove analytically that its exact three-soliton solution has a ninefold maximum amplification that is achieved in the absence of spatial divergence. Reproducing this [...]

## Progression of the surge in the Negribreen Glacier System from two years of ICESat-2 measurements

**Published**: 2023-10-08

**Subjects**: Applied Mathematics, Earth Sciences, Physical Sciences and Mathematics

The unique measurement capabilities of ICESat-2 allow high spatiotemporal resolution of complex ice-dynamic processes that occur during a surge. Detailed and precise mapping of height changes on surge glaciers has previously escaped observations from space due to limited resolution of space-borne altimeter data and the surface characteristics of glaciers during surge such as heavy crevassing. [...]

## Omnivariant Generalized Least Squares Regression: Theory, Geochronological Applications, and Making the Case for Reconciled Δ47 calibrations

**Published**: 2023-09-22

**Subjects**: Applied Mathematics, Earth Sciences, Geochemistry

Least-squares regression methods are mathematically powerful, conceptually and computationally simple, and widely used in many fields. However, none of the commonly-used flavors of least-squares regression, such as York regression or Generalized Least Squares (GLS), take into account the full set of covariances between all observed (x,y) values. Here we describe the Omnivariant Generalized Least [...]

## Linear analysis of ice-shelf topography response to basal melting and freezing

**Published**: 2023-04-28

**Subjects**: Applied Mathematics, Dynamic Systems, Earth Sciences, Fluid Dynamics, Glaciology, Physical Sciences and Mathematics, Physics

Floating ice shelves in Antarctica and Greenland limit land-ice contributions to sea level rise by resisting the flow of grounded ice. Melting at the surface and base of ice shelves can lead to destabilisation by promoting thinning and fracturing. Basal melting often results in channelised features that manifest as surface topography due to buoyancy. The assumption of hydrostatic flotation [...]

## Numerical simulation of meteorite impact on basaltic lavas at Lonar Crater, India

**Published**: 2023-01-28

**Subjects**: Applied Mathematics, Astrophysics and Astronomy, Planetary Sciences

Lonar lake is a hypervelocity impact crater formed in a basaltic terrain of Deccan Traps in the state of Maharashtra, India. The crater has an approximate radius of 915 m and an average depth of about 137 m. Here we report the results of our numerical investigations aimed to elucidate the physical characteristics of incoming asteroid. For realistic simulation, we not only consider [...]

## Estimating the Occurrence of Slow Slip Events and Earthquakes with an Ensemble Kalman Filter

**Published**: 2022-08-07

**Subjects**: Applied Mathematics, Earth Sciences, Physical Sciences and Mathematics

Our ability to forecast earthquakes and slow slip events is hampered by limited information on the current state of stress on faults. Ensemble data assimilation methods permit estimating the state by combining physics-based models and observations, while considering their uncertainties. We employ an Ensemble Kalman Filter (EnKF) to estimate shear stresses, slip rates, and the state theta acting [...]

## A High-order Accurate Summation-by-Parts Finite Difference Method for Fully-dynamic Earthquake Sequence Simulations within Sedimentary Basins

**Published**: 2022-08-06

**Subjects**: Applied Mathematics, Earth Sciences, Physical Sciences and Mathematics

We present a computationally efficient numerical method for earthquake sequences that incorporates wave propagation during rupture. A vertical strike-slip fault governed by rate-and-state friction is embedded in a heterogeneous elastic half-space discretized using a high-order accurate Summation-by-Parts finite difference method. We develop a two solver approach: Adaptive time-stepping is [...]

## A computational framework for time dependent deformation in viscoelastic magmatic systems

**Published**: 2022-04-01

**Subjects**: Applied Mathematics, Computer Sciences, Earth Sciences, Mathematics

Time-dependent ground deformation is a key observable in active magmatic systems, but is challenging to characterize. Here we present a numerical framework for modeling transient deformation and stress around a subsurface, spheroidal pressurized magma reservoir within a viscoelastic half-space with variable material coefficients, utilizing a high-order finite-element method and explicit [...]

## Multilevel multifidelity Monte Carlo methods for assessing coastal flood risk

**Published**: 2022-03-14

**Subjects**: Applied Mathematics, Earth Sciences, Hydrology, Risk Analysis, Statistical Methodology, Statistics and Probability

When choosing an appropriate hydrodynamic model, there is always a compromise between accuracy and computational cost, with high fidelity models being more expensive than low fidelity ones. However, when assessing uncertainty, we can use a multifidelity approach to take advantage of the accuracy of high fidelity models and the computational efficiency of low fidelity models. Here, we apply the [...]

## Diapycnal Displacement, Diffusion, and Distortion of Tracers in the Ocean

**Published**: 2022-01-07

**Subjects**: Applied Mathematics, Fluid Dynamics, Non-linear Dynamics, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Small-scale mixing drives the diabatic upwelling that closes the abyssal ocean overturning circulation. Indirect microstructure measurements of in situ turbulence suggest that mixing is bottom enhanced over rough topography, implying downwelling in the interior and stronger upwelling in a sloping bottom boundary layer. Tracer release experiments (TREs), in which inert tracers are purposefully [...]

## Dynamics of Eddying Abyssal Mixing Layers over Sloping Rough Topography

**Published**: 2022-01-07

**Subjects**: Applied Mathematics, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

The abyssal overturning circulation is thought to be primarily driven by small-scale turbulent mixing. Diagnosed water-mass transformations are dominated by rough topography “hotspots,” where the bottom enhancement of mixing causes the diffusive buoyancy flux to diverge, driving widespread downwelling in the interior—only to be overwhelmed by an even stronger upwelling in a thin bottom boundary [...]

## A review of model-based scenario analysis of poverty for informing sustainability

**Published**: 2021-11-22

**Subjects**: Applied Mathematics, Dynamic Systems, Environmental Sciences, Natural Resources Management and Policy, Physical Sciences and Mathematics, Sustainability

Ending poverty in all its forms everywhere is the first goal being targeted by the United Nations 2030 Agenda for Sustainable Development. Poverty eradication is a long-term process that faces the challenges of many uncertainties and complex interactions with other Sustainable Development Goals (SDGs). In order to better understand poverty and contribute to addressing poverty in a sustainable [...]

## Calibration, inversion and sensitivity analysis for hydro-morphodynamic models

**Published**: 2021-08-03

**Subjects**: Applied Mathematics, Fluid Dynamics, Geomorphology, Numerical Analysis and Computation, Partial Differential Equations, Programming Languages and Compilers

The development of reliable, sophisticated hydro-morphodynamic models is essential for protecting the coastal environment against hazards such as flooding and erosion. There exists a high degree of uncertainty associated with the application of these models, in part due to incomplete knowledge of various physical, empirical and numerical closure related parameters in both the hydrodynamic and [...]

## Modeling P waves in seismic noise correlations: Advancing fault monitoring using train traffic sources

**Published**: 2021-06-19

**Subjects**: Applied Mathematics, Earth Sciences, Geophysics and Seismology, Physics

The theory of Green's function retrieval essentially requires homogeneously distributed noise sources. Even though these conditions are not fulfilled in nature, low-frequency (<1 Hz) surface waves generated by ocean-crust interactions have been used successfully to image the crust with unprecedented spatial resolution. In contrast to low-frequency surface waves, high-frequency (>1 Hz) body waves [...]

## Detection of Interannual Ensemble Forecast Signals over the North Atlantic and Europe using Atmospheric Circulation Regimes

**Published**: 2021-05-27

**Subjects**: Applied Mathematics, Atmospheric Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

To study the forced variability of atmospheric circulation regimes, the use of model ensembles is often necessary for identifying statistically significant signals as the observed data constitute a small sample and are thus strongly affected by the noise associated with sampling uncertainty. However, the regime representation is itself affected by noise within the atmosphere, which can make it [...]