Nonlinear Processes in Geosciences

NPG Paper of the Month: “Recurrence analysis of extreme event-like data”

Abhirup Banerjee July 1, 2021

Top panels: time series of a periodic (left), stochastic (middle), and chaotic system (right). Bottom panels: the corresponding recurrence plots of respective systems.

The May 2021 NPG Paper of the Month award goes Abhirup Banerjee and his co-authors for their paper “Recurrence analysis of extreme event-like data“. Abhirup is pursuing a doctoral degree in Theoretical Physics at University of Potsdam. He is working at Potsdam Institute of Climate Impact Research as a guest researcher as part of the DFG funded NatRiskChange project. In this project, he ...[Read More]

When carbon emissions break nature: icebergs and their feedback to climate change

Davide Faranda May 21, 2021

This image distributed by the European Space Agency (ESA) on May 20, 2021 shows a view of the A-76 iceberg off the Ronne sea ice in the Weddell Sea, Antarctica. It was captured by the Copernicus Sentinel-1 mission. Credits: ESA.

The largest iceberg in the world, named A-76, about 170 km long and 25 km wide, is drifting away from the Ronne pack ice in Antarctica. A76, originally spotted by the British Antarctic Survey (BAS), a British polar research organization with a base nearby, will wander and melt in the Weddell Sea, according to a statement released Wednesday, May 20, by the European Space Agency. Several studies are ...[Read More]

NPG Paper of the Month: “Ordering of trajectories reveals hierarchical finite-time coherent sets in Lagrangian particle data: detecting Agulhas rings in the South Atlantic Ocean”

David Wichmann March 16, 2021

Result of the OPTICS algorithm applied to the trajectories modelled in the Bickley Jet model flow. (a), (d) and (g) show the reachability plot with different DBSCAN clustering results, indicated by the black horizontal line. The corresponding clustering results of each choice of DBSCAN parameter is shown on the right of the reachability plots for different times. Grey particles correspond to noise. Axis units in the centre and right column are in 1000 km.

The February 2021 NPG Paper of the Month award goes David Wichmann and his co-authors for their paper “Ordering of trajectories reveals hierarchical finite-time coherent sets in Lagrangian particle data: detecting Agulhas rings in the South Atlantic Ocean“. Understanding the transport of tracers and particulates is an important topic in oceanography and in fluid dynamics in general. Th ...[Read More]

NPG Paper of the Month: “A methodology to obtain model-error covariances due to the discretization scheme from the parametric Kalman filter perspective”

Tommaso Alberti March 11, 2021

Illustration of the transport of a chemical specy by a heterogeneous wind field over a 1D domain (a) and the numerical simulation from a simple discretization scheme (b). The loss of variance due to the spurious numerical diffusion involves an increase of the model-error variance (c) which is coupled with the anisotropy (the correlation length-scale in 1D domain, in panel d).

The January 2021 NPG Paper of the Month award goes to Olivier Pannekoucke and his co-authors for the paper “A methodology to obtain model-error covariances due to the discretization scheme from the parametric Kalman filter perspective“. In geophysics, forecasting is based on solving the equations of physics with the help of a computer. To calculate a forecast we need an initial conditi ...[Read More]