Nonlinear Processes in Geosciences
Tommaso Alberti

Tommaso Alberti

I am a postdoctoral researcher at the Institute for Space Astrophysics and Planetology, an Institute within INAF (National Institute for Astrophysics), in Rome, Italy. My work focuses on nonlinear dynamical system approaches and time series analysis in geosciences with particular interests in solar wind – magnetosphere – ionosphere interactions and coupling, space and near-Earth plasma turbulence, and Earth’s climate dynamics. I am the Early Career Scientists Representative for the Nonlinear Processes in Geosciences (NP) Division.

NPG Paper of the Month: “Unravelling the spatial diversity of Indian precipitation teleconnections via a non-linear multi-scale approach”

Schematic map of spatial diversity of Indian precipitation teleconnections at different time scales. (a) ENSO, (b) IOD, (c) NAO, (d PDO, and (e) AMO. Colors are consistent with the Indian community shown in the right figure. Presence of color in community segment indicates significant synchronization between teleconnection and Indian precipitation. Every single segment of circle shows the temporal scale. Cardinal direction has been projected in the background of each circle.

Today’s we launch one of our promised activities: the NPG Paper of the Month.
This month the award is achieved by Jürgen Kurths and co-authors for their paper “Unravelling the spatial diversity of Indian precipitation teleconnections via a non-linear multi-scale approach” (
Ankit Agarwal, one of the authors of the manuscript, tells us about the importance of the results achieved with this paper where the authors gained insights on spatial diversity of Indian precipitation teleconnections by studying the effects of global climate indices on Indian precipitation patterns at varying timescales.
Ankit is a hydro-climatologist at the Potsdam Institute for Climate Impact Research and Helmholtz Center for Geosciences, section 5.4 (Hydrology). He is interested in interdisciplinary research to understand multi-scale interactions among different components of Earth. He develops new methods and apply them in hydrology and climatology for advance understanding. His next position is due as an assistant professor at the Department of Hydrology, Indian Institute of Technology-Roorkee, India.

Atmospheric and oceanic phenomena are characterized by multi-scale behavior and their influence on precipitation varies across multiple timescales. Understanding the spatiotemporal variability of coupling between various global climate indices and precipitation is of great importance for accurate prediction of climatic variations on different time-scales. While this coupling has been investigated before, it has been a challenge to address its non-linear, scale-varying, and spatially diverse behavior. The study by Kurths et al., 2019 proposes a novel, and general, framework to disentangle the non-linear dependency structure between rainfall and climate patterns across space and temporal scales, by introducing the concept of multiscale event synchronization (Agarwal et al., 2017).
More specifically, the study examines the spatial diversity of Indian precipitation teleconnection at different time scales, first by identifying homogenous communities (Agarwal et al., 2018) and later by computing nonlinear linkages between the identified communities (spatial regions) and dominant climatic patterns, represented by climatic indices such as El-Nino Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO) and Atlantic multi-decadal Oscillation (AMO). The results of the study unravel the spatial variation of the climate indices across India and across time scales. In particular, ENSO and the (IOD) exhibit precipitation teleconnections in the peninsular and southeast areas of India on interannual and decadal scales, respectively, whereas the North Atlantic Oscillation (NAO) has a strong connection to precipitation particularly in the northern regions (refer to the figure). The effect of PDO is seen across the entire country, while precipitation variations over the semi-arid and arid regions of Central India have linkages to the AMO. The proposed method provides a powerful approach for capturing the dynamics of influences of climatic indices on Indian precipitation and, hence, helps improving precipitation forecasting.

A comparison of the results with the state-of-the-art method, wavelet coherence, shows that the proposed method has much higher skill in detecting linkages between the Indian monsoon system and climate patterns. The authors believe that the findings presented in the paper will appeal to the broader society of Earth scientists and modelers given the problems they face in understanding the dynamics and forecasting Indian precipitation.


Kurths, J., Agarwal, A., Shukla, R., Marwan, N., Rathinasamy, M., Caesar, L., Krishnan, R., and Merz, B.: Unravelling the spatial diversity of Indian precipitation teleconnections via a non-linear multi-scale approach, Nonlin. Processes Geophys., 26, 251-266,, 2019.

Agarwal, A., Marwan, N., Maheswaran, R., Merz, B., Kurths, J.: Quantifying the roles of single stations within homogeneous regions using complex network analysis, Journal of Hydrology, 563, 802-810,, 2018.

Agarwal, A., Marwan, N., Rathinasamy, M., Merz, B., Kurths, J.: Multi-scale event synchronization analysis for unravelling climate processes: a wavelet-based approach, Nonlin. Processes Geophys., 24, 599-611,, 2017.

NP Interviews: the Division President Stéphane Vannitsem

NP Interviews: the Division President Stéphane Vannitsem

Today’s NP Interviews hosts the Nonlinear Processes Division President Stéphane Vannitsem.

Stéphane is the head of the Dynamical Meteorology and Climatology Unit of the Research division of the Royal Meteorological Institute of Belgium, and lecturer at the Free University of Brussels. He is currently president of the Nonlinear Processes division of the European Geosciences Union and executive editor of the journal “Nonlinear Processes in Geophysics”. His main research interests and expertise are oriented toward the application and adaptation of techniques of dynamical systems theory, chaos theory and stochastic processes to the study of atmospheric and climate dynamics with emphasis on their variability and predictability.

What is the NP Division?

The Nonlinear Processes in Geosciences (NP) Division was born at the early stages of the development of the Union, at that time the European Geophysical Society (EGS), with the aim at promoting new techniques and theories on the properties and dynamics of systems displaying nonlinearities.

Why are nonlinearities important?

Nonlinearities are generic in our environment and are at the heart of the complexity of the systems geoscientists are dealing with. As these nonlinearities are affecting all fields of geosciences, the NP division is a truly interdisciplinary (even transdisciplinary) division attracting scientists working on nonlinear problems and/or at the crossroads between different disciplines.

What are these disciplines and aspects?

The main themes covered by our interdisciplinary division and the corresponding officers are listed at Aspects covered are the mathematics, the dynamics, the modelling and the statistics of nonlinear processes in all geosciences fields from the Earth interior to the outer space.

What about sessions and short courses during the General Assembly?

As an interdisciplinary division dealing with state-of-the-art and brand new techniques and with new nonlinear mechanisms, NP is of course promoting co-organization of sessions with the other divisions. At the same time, members of the division are proposing short courses in which advanced techniques are presented. These courses have a lot of success among young scientists, and are usually full and often people are standing outside the rooms. These courses are definitely a success for the NP division, allowing for more visibility of our activities and a faster diffusion of new promising approaches and new nonlinear mechanisms.

Great! Are there also some awards and medals?

On top of the usual oral and poster presentations, the NP division awards excellent young scientists by means of an outstanding Early Career Scientist (ECS) Award and for more accomplished scientists through the Lewis Fry Richardson Medal. The latter has been first awarded in 2004 and the list of awardees can be found at Lewis Fry Richardson was a pioneer in turbulence in which nonlinearities are the generic elements of the complex behavior of the fluid, and had also a strong vision on how numerical weather prediction should be made. All awardees have substantially contributed to advancing our understanding of the impact of nonlinearities throughout geosciences. The NP ECS Award was first delivered in 2011 and the list of young awardees can also be found at, illustrating how lively this field is and how young scientists are still enthusiastic by the problems to be solved from the challenging Earth System evolution to Solar Flares, or Rogue waves (without being exhaustive at all).

How large is the NP Division?

Since its start, the NP Division has grown in size until to reach an average of 300-400 abstracts per year. This size is obviously small as compared to the main divisions of the EGU that can reach several thousands of abstracts, but plays an essential role in diffusing new advanced techniques throughout the Union.

Is there a publishing journal for researchers in nonlinear processes?

The NP division members have set up in the early days of the EGS a journal “Nonlinear Processes in Geophysics”. This journal published by the EGU – and co-listed among the partner journals of the AGU – covers all aspects of nonlinear geophysics. The impact factor is not high, but the quality of papers and new ideas is. This forum is clearly a place for promoting research on nonlinear processes, and I encourage young scientists to take part of the nonlinear adventure by submitting good papers to this journal. The link to the journal is at

Welcome to the Nonlinear Processes in Geosciences Blog!

Welcome to the Nonlinear Processes in Geosciences Blog!

We are happy to announce that the growing Nonlinear Processes in Geosciences (NP) community has a new unifying platform where newsworthy information on different topics will be published, with the main aim to reach many scientists at a time.

Thus, this is the official launch of the Nonlinear Processes in Geosciences Blog!

We hope this platform could serve as a starting point to strengthen our community, increase its numbers, improve communication among us, and play an essential role throughout the European Geosciences Union.

Thus, we welcome you to contribute guest articles to our blog and we especially encourage posts on:

  • upcoming events, conferences, workshops, schools;
  • outstanding research of early career scientists;
  • outstanding and review works of established scientists;
  • job opportunities and search for academic and non-academic positions;
  • interesting funded projects on all aspects of geosciences;
  • new technological, methodological, and pedagogical developments;
  • all other ideas of interests for the NP community.

In addition to the above exciting ideas we will also launch two different activities:

  1. NP Interviews”: an interview with scientists belonging to the NP Division in relation to their activities for the division itself;
  2. NPG Paper of the Month”: a dedicated post to a selected paper from the Nonlinear Processes in Geophysics journal.


We would like to make the blog a success … so we are really looking forward to your contributions! Please feel free to contact us at if you want to pitch a blog post idea!

Tommaso Alberti, Davide Faranda, Christian Franzke, Anna von der Heydt, Stéphane Vannitsem