Nonlinear Processes in Geosciences

NP Campfire: “Scaling and multifractals : from historical perspectives to recent developments”

Auguste Gires, Tommaso Alberti and Yongxiang Huang December 20, 2021

$NP Campfire: “Scaling and multifractals : from historical perspectives to recent developments”$

Adapted from G. Sarma et al. (1991).

Scaling law behaviours are ubiquitous in geosciences both from a theoretical and practical point of view. They are required to better understand, analyse and simulate the underlying processes, which yields the observed variability of geophysical fields over wide ranges of spatio-temporal scales. A group of scientists within the Nonlinear Processes in Geosciences (NP) Division of the European Geosc ...[Read More]

NPG Paper of the Month: “Comparing estimation techniques for temporal scaling in palaeoclimate time series”

Raphaël Hébert December 14, 2021

The NPG paper of the month of July was awarded to Comparing estimation techniques for temporal scaling in palaeoclimate time series by Raphaël Hébert, Kira Rehfeld and Thomas Laepple (https://doi.org/10.5194/npg-28-311-2021). Raphaël Hébert is currently a post-doctoral researcher at the Alfred-Wegener-Institut in Potsdam (Germany) in the Earth System Diagnostics group of Thomas Laepple, where he a ...[Read More]

Exploring the multistable and multiscale climate system via noise

Georgios Margazoglou December 7, 2021

Could our present day “warm” climate turn into a frozen fully glaciated one, as if the whole Earth is a huge “snowball”? That was a question put forward independently by Mikhail Budyko and William Sellers in the late 60s [1,2] who made a first estimate of the necessary changes of incoming solar radiation, such that either the Arctic ice sheet completely melts, or the planet gets fully frozen. Base ...[Read More]

NPG Paper of the Month: “Empirical evidence of a fluctuation theorem for the wind mechanical power input into the ocean”

Achim Wirth November 4, 2021

The pdf p(z,τ) (left) and the symmetry function normalised by the averaging time S(z,τ)/τ (right) as a function of the power input z for different averaging times τ (see caption). The variable τ gives the length of the averaging interval in terms of observations done every 6 hours. Data are for the recirculation area of the Atlantic subtropical gyre at a resolution of 0.5o in space and 6 hours in time for the period of 1993–2016. Note that the pdfs differ from Gaussian. The symmetry function converges to a straight line for increasing averaging periods, showing evidence of a FT. License: “Empirical evidence of a fluctuation theorem for the wind mechanical power input into the ocean".

This month the NPG Paper of the Month award is achieved by Achim Wirth for his paper “Empirical evidence of a fluctuation theorem for the wind mechanical power input into the ocean“. Achim obtained his PhD at the University of Nice (Franc), doing research on turbulence theory. He then moved to oceanography working at UCLA (USA) and Geomar (Germany). Since 2005 he holds a permanent position a ...[Read More]