Atmospheric Dynamics Leading to West European Summer Hot Temperatures Since 1851

In Western Europe, several recent summers have been exceptionally warm, especially the summers of 2003 and 2015. Based on observations over the past century, meteorologists have come to see such major heat events as typically stemming from anticyclonic atmospheric circulation and a lack of spring rainfall in Southern Europe. Read more

Microfoundations of Discounting

Economists routinely model how people choose between different options. For example, a common issue is time delay: would you choose to receive £100 today, or prefer £200 next month? Read more

Generalized dimensions, large deviations and the distribution of rare events

Any fractal set possesses a unique dimension, which characterises its self-similar behaviour under a change of scale. The attractors of many dynamical systems are more complex multifractals, which possess a spectrum of dimensions, or “generalized” dimensions. Read more

Dynamical characterization of stochastic bifurcations in a random logistic map

The interaction of noise and non-linearity can cause sharp dynamical transitions, as appear in phenomena such as stochastic resonance or noise-induced synchronization or chaos. Read more

First passage and first hitting times of Lévy flights and Lévy walks

In many areas of science and applied mathematics, important events often get initiated when a stochastic variable crosses a threshold value. Financial assets may be sold at a particular price, or a chemical reaction initiated when two particles come close enough. Read more

Seismological investigations of induced earthquakes near the Hutubi underground gas storage facility

Earth scientists have long known that fluid injected into the Earth’s crust can induce earthquakes. In principle, seismic activity may also be triggered through gas extraction through the mechanism of poroelastic stress perturbation, although such events have been observed less frequently. Read more

Minimal dynamical systems model of the Northern Hemisphere jet stream via embedding of climate data

Jet streams are narrow, fast-flowing westerly air currents located near the tropopause, the tropospheric boundary with the higher stratosphere. These jets play a major role in driving the large-scale atmospheric circulation and modulate the frequency, severity and persistence of weather events at middle latitudes. Read more

Spectral theory for the stability of dynamical systems on large oriented locally tree-like graphs

The linear stability of large complex systems around their stationary points can be studied with random matrix theory. In one common model, the i.i.d. random matrix model, one assumes a simple statistical form for the interactions between distinct elements of a network. Read more

Bayesian approach for network adjustment for gravity survey campaign: methodology and model test

Variations in the strength of gravity over the Earth’s surface reflect underlying geophysical changes such as groundwater change, surface vertical deformation, tectonic events, earthquakes and other processes. To study such processes, so-called gravity survey campaigns collect observations made repeatedly at fixed stations. Read more

Scale interactions and anisotropy in stable boundary layers

Some of the strongest challenges for numerical weather prediction come from the unsteady nature of certain flows, in particular nocturnal and stable boundary layers. Read more