Articles | Volume 22, issue 2
https://doi.org/10.5194/npg-22-187-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/npg-22-187-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
25 Mar 2015
Research article |
| 25 Mar 2015
Statistical optimization for passive scalar transport: maximum entropy production versus maximum Kolmogorov–Sinai entropy
M. Mihelich
Laboratoire SPHYNX, CEA/IRAMIS/SPEC, CNRS URA 2464, 91191 Gif-sur-Yvette, France
D. Faranda
Laboratoire SPHYNX, CEA/IRAMIS/SPEC, CNRS URA 2464, 91191 Gif-sur-Yvette, France
Laboratoire SPHYNX, CEA/IRAMIS/SPEC, CNRS URA 2464, 91191 Gif-sur-Yvette, France
D. Paillard
Laboratoire SPHYNX, CEA/IRAMIS/SPEC, CNRS URA 2464, 91191 Gif-sur-Yvette, France
Related authors
No articles found.
Adrien Burq, Jean Jouhaud, Victor Xing, Victor Bouvier, Vincent Forcadell, Mateusz Taszarek, Mathieu Vrac, and Davide Faranda
EGUsphere, https://doi.org/10.5194/egusphere-2026-4363, https://doi.org/10.5194/egusphere-2026-4363, 2026
This preprint is open for discussion and under review for Earth System Dynamics (ESD).
Short summary
Short summary
Lightning is a small-scale process that climate and weather models cannot compute exactly, so it must be approximated. Here we build a deep learning model that predicts lightning across a whole region at once, using inputs from the whole region, and compare it to models that predict each pixel separately. Using this larger-scale information proves beneficial: our model outperforms the single-pixel ones. We also identify the spatial scale and the environmental predictors that matter most.
Tom Dörffel, Natalia Mikula, Lisa Schielicke, Theresa Kiszler, Davide Faranda, Berengere Dubrulle, and Nikki Vercauteren
EGUsphere, https://doi.org/10.5194/egusphere-2026-2918, https://doi.org/10.5194/egusphere-2026-2918, 2026
Short summary
Short summary
We investigate how two different indicators related to measures of energy transfer can be used to assess the dynamics of tropical cyclones. One indicator is based on the energy redistribution across length-scales and the other one is based on more fundamental thermodynamic principles. This research demonstrates the potential of these indicators of being used as predictors for the intensity change of tropical cyclones even in under-resolved simulations.
Clara Naldesi, Nathalie Bertrand, Davide Faranda, and Mathieu Vrac
EGUsphere, https://doi.org/10.5194/egusphere-2026-1466, https://doi.org/10.5194/egusphere-2026-1466, 2026
Short summary
Short summary
The public increasingly needs to know whether and how climate change influences specific extreme events. ClimaMeter is a scientific tool designed to address this demand. This paper reviews the ClimaMeter methodology, focusing on how it estimates the relative roles of natural variability and climate change. We propose a more flexible and general approach within the same framework, enabling a more nuanced assessment of natural variability.
Didier Paillard
Clim. Past, 22, 647–673, https://doi.org/10.5194/cp-22-647-2026, https://doi.org/10.5194/cp-22-647-2026, 2026
Short summary
Short summary
This paper presents classical and new mathematical formulas to compute various "flavors" of the insolation forcing used to interpret paleoclimatic series, or to simulate climate at different times. It provides a description of the usual concepts while insisting on the difficulties associated with them, like the definition of a calendar. Then it presents novel formulas to compute extrema of insolation for a given latitude. It thus presents a new open-source software package available online.
Tommaso Alberti, Davide Faranda, Mohamed Foudad, Erika Coppola, Lia Rapella, Rachel Burbidge, Miguel A. C. Teixeira, and Paul Williams
EGUsphere, https://doi.org/10.5194/egusphere-2026-1178, https://doi.org/10.5194/egusphere-2026-1178, 2026
Short summary
Short summary
We developed TurboMeter to study whether climate change is making airplane turbulence stronger. By comparing current atmospheric conditions with similar past situations, we find that most turbulence events in 2024 were intensified by human-caused climate change, especially over the North Atlantic, East Asia, and the United States. This work shows that climate change is already affecting flight safety and highlights the need for climate-informed planning in aviation.
Greta Cazzaniga, Anastasia Akakpo-Numado, Patrick Brockmann, Adrien Burq, Mathieu Vrac, and Davide Faranda
EGUsphere, https://doi.org/10.5194/egusphere-2026-1175, https://doi.org/10.5194/egusphere-2026-1175, 2026
Short summary
Short summary
Extreme weather events are becoming more frequent and severe, creating a strong need for rapid and reliable information. We developed an open tool that automatically detects and tracks heatwaves, cold spells, heavy rain, and strong winds across Europe, both in real time and in past decades. By comparing current events with long historical records, the tool shows how unusual an event is and reveals clear increases in heatwaves, while other hazards show more mixed changes.
Valerio Lembo, Gabriele Messori, Davide Faranda, Vera Melinda Galfi, Rune Grand Graversen, and Flavio Emanuele Pons
Weather Clim. Dynam., 7, 453–473, https://doi.org/10.5194/wcd-7-453-2026, https://doi.org/10.5194/wcd-7-453-2026, 2026
Short summary
Short summary
Hemispheric heatwaves have fundamental implications for ecosystems and societies. They are studied together with large-scale atmospheric dynamics, through the lens of poleward heat transports by planetary-scale waves. Extremely weak transports of heat towards the North Pole are found to be associated with hemispheric heatwaves in the Northern Hemisphere mid-latitudes. Therefore, we conclude that heat transports are a possible indicator and a precursor of concurrent hemispheric heatwaves.
Davide Faranda, Lucas Taligrot, Pascal Yiou, and Nada Caud
Geosci. Commun., 9, 115–125, https://doi.org/10.5194/gc-9-115-2026, https://doi.org/10.5194/gc-9-115-2026, 2026
Short summary
Short summary
We developed a free online game called ClimarisQ to help people better understand climate change and extreme weather. By playing the game, users learn how decisions about the environment, money, and public opinion affect future risks. We studied how players reacted and found that the game makes climate issues easier to grasp and encourages discussion. This shows that interactive tools like games can support learning and action on climate and environmental challenges.
Jean-Baptiste Brenner, Aurélien Quiquet, Didier M. Roche, Didier Paillard, and Pradeebane Vaittinada Ayar
Geosci. Model Dev., 19, 1075–1101, https://doi.org/10.5194/gmd-19-1075-2026, https://doi.org/10.5194/gmd-19-1075-2026, 2026
Short summary
Short summary
Due to the limited spatial and temporal coverage of observations, global models are essential tools to study climate. However, long-term climate data at fine spatial scale are difficult to obtain because of elevated computational costs such algorithms involve. This paper presents a simple model based on the description of climate/topography interactions to generate local precipitation fields at low cost. The objective is to provide a flexible and easy to use method for paleoclimate studies.
Davide Faranda, Thibault Guinaldo, Francisco Pastor, Tommaso Alberti, and Samira Khodayar
EGUsphere, https://hal.science/hal-05289765v1, https://hal.science/hal-05289765v1, 2026
Short summary
Short summary
The Mediterranean Sea experienced a record-breaking heatwave in summer 2025. We compared this event to similar patterns from past decades to see how a warmer climate changed its strength. We found that today's warmer background added about 1.5 °C to the sea surface, making the heatwave far more intense and widespread. This shows how climate change is turning ordinary weather patterns into extreme events, with major impacts on marine life, coastal communities, and economies.
Emmanouil Flaounas, Stavros Dafis, Silvio Davolio, Davide Faranda, Christian Ferrarin, Katharina Hartmuth, Assaf Hochman, Aristeidis Koutroulis, Samira Khodayar, Mario Marcello Miglietta, Florian Pantillon, Platon Patlakas, Michael Sprenger, and Iris Thurnherr
Weather Clim. Dynam., 6, 1515–1538, https://doi.org/10.5194/wcd-6-1515-2025, https://doi.org/10.5194/wcd-6-1515-2025, 2025
Short summary
Short summary
Storm Daniel (2023) is one of the most catastrophic storms ever documented in the Mediterranean. Our results highlight the different dynamics and therefore the different predictability skill of precipitation, its extremes and impacts that have been produced in Greece and Libya, the two most affected countries. Our approach concerns an analysis of the storm by articulating dynamics, weather prediction, hydrological and oceanographic implications, climate extremes, and attribution theory.
Pradeebane Vaittinada Ayar, Stella Bourdin, Davide Faranda, and Mathieu Vrac
Nat. Hazards Earth Syst. Sci., 25, 4655–4672, https://doi.org/10.5194/nhess-25-4655-2025, https://doi.org/10.5194/nhess-25-4655-2025, 2025
Short summary
Short summary
Tracking tropical cyclones (TCs) remains a matter of interest for investigating observed and simulated tropical cyclones. In this study, Random Forest (RF), a machine learning approach, is considered to track TCs. RF associates the TC occurrence or absence with different atmospheric configurations. Compared to trackers found in the literature, it shows similar performance for tracking TCs, better control over false alarms, more flexibility, and reveals key variables for TCs' detection.
Lia Rapella, Tommaso Alberti, Davide Faranda, and Philippe Drobinski
Weather Clim. Dynam., 6, 1339–1363, https://doi.org/10.5194/wcd-6-1339-2025, https://doi.org/10.5194/wcd-6-1339-2025, 2025
Short summary
Short summary
Extreme weather events pose increasing challenges for aviation, including flight disruptions and infrastructure damage. This study examines the influence of anthropogenic climate change on four recent major storms across Europe, the USA, and East Asia. Our research underscores the growing intensity of extreme storms, driven by human-induced climate change, stressing the need to adapt aviation strategies to an increasingly hazardous environment.
Kerry Emanuel, Tommaso Alberti, Stella Bourdin, Suzana J. Camargo, Davide Faranda, Emmanouil Flaounas, Juan Jesus Gonzalez-Aleman, Chia-Ying Lee, Mario Marcello Miglietta, Claudia Pasquero, Alice Portal, Hamish Ramsay, Marco Reale, and Romualdo Romero
Weather Clim. Dynam., 6, 901–926, https://doi.org/10.5194/wcd-6-901-2025, https://doi.org/10.5194/wcd-6-901-2025, 2025
Short summary
Short summary
Storms strongly resembling hurricanes are sometimes observed to form well outside the tropics, even in polar latitudes. They behave capriciously, developing very rapidly and then dying just as quickly. We show that strong dynamical processes in the atmosphere can sometimes cause it to become much colder locally than the underlying ocean, creating the conditions for hurricanes to form but only over small areas and for short times. We call the resulting storms "CYCLOPs".
Robin Noyelle, Davide Faranda, Yoann Robin, Mathieu Vrac, and Pascal Yiou
Weather Clim. Dynam., 6, 817–839, https://doi.org/10.5194/wcd-6-817-2025, https://doi.org/10.5194/wcd-6-817-2025, 2025
Short summary
Short summary
Properties of extreme meteorological and climatological events are changing under human-caused climate change. Extreme event attribution methods seek to estimate the contribution of global warming in the probability and intensity changes of extreme events. Here we propose a procedure to estimate these quantities for the flow analogue method, which compares the observed event to similar events in the past.
Ferran Lopez-Marti, Mireia Ginesta, Davide Faranda, Anna Rutgersson, Pascal Yiou, Lichuan Wu, and Gabriele Messori
Earth Syst. Dynam., 16, 169–187, https://doi.org/10.5194/esd-16-169-2025, https://doi.org/10.5194/esd-16-169-2025, 2025
Short summary
Short summary
Explosive cyclones and atmospheric rivers are two main drivers of extreme weather in Europe. In this study, we investigate their joint changes in future climates over the North Atlantic. Our results show that both the concurrence of these events and the intensity of atmospheric rivers increase by the end of the century across different future scenarios. Furthermore, explosive cyclones associated with atmospheric rivers last longer and are deeper than those without atmospheric rivers.
Davide Faranda, Gabriele Messori, Erika Coppola, Tommaso Alberti, Mathieu Vrac, Flavio Pons, Pascal Yiou, Marion Saint Lu, Andreia N. S. Hisi, Patrick Brockmann, Stavros Dafis, Gianmarco Mengaldo, and Robert Vautard
Weather Clim. Dynam., 5, 959–983, https://doi.org/10.5194/wcd-5-959-2024, https://doi.org/10.5194/wcd-5-959-2024, 2024
Short summary
Short summary
We introduce ClimaMeter, a tool offering real-time insights into extreme-weather events. Our tool unveils how climate change and natural variability affect these events, affecting communities worldwide. Our research equips policymakers and the public with essential knowledge, fostering informed decisions and enhancing climate resilience. We analysed two distinct events, showcasing ClimaMeter's global relevance.
Quentin Pikeroen, Didier Paillard, and Karine Watrin
Geosci. Model Dev., 17, 3801–3814, https://doi.org/10.5194/gmd-17-3801-2024, https://doi.org/10.5194/gmd-17-3801-2024, 2024
Short summary
Short summary
All accurate climate models use equations with poorly defined parameters, where knobs for the parameters are turned to fit the observations. This process is called tuning. In this article, we use another paradigm. We use a thermodynamic hypothesis, the maximum entropy production, to compute temperatures, energy fluxes, and precipitation, where tuning is impossible. For now, the 1D vertical model is used for a tropical atmosphere. The correct order of magnitude of precipitation is computed.
Lucas Fery and Davide Faranda
Weather Clim. Dynam., 5, 439–461, https://doi.org/10.5194/wcd-5-439-2024, https://doi.org/10.5194/wcd-5-439-2024, 2024
Short summary
Short summary
In this study, we analyse warm-season derechos – a type of severe convective windstorm – in France between 2000 and 2022, identifying 38 events. We compare their frequency and features with other countries. We also examine changes in the associated large-scale patterns. We find that convective instability has increased in southern Europe. However, the attribution of these changes to natural climate variability, human-induced climate change or a combination of both remains unclear.
Emma Holmberg, Gabriele Messori, Rodrigo Caballero, and Davide Faranda
Earth Syst. Dynam., 14, 737–765, https://doi.org/10.5194/esd-14-737-2023, https://doi.org/10.5194/esd-14-737-2023, 2023
Short summary
Short summary
We analyse the duration of large-scale patterns of air movement in the atmosphere, referred to as persistence, and whether unusually persistent patterns favour warm-temperature extremes in Europe. We see no clear relationship between summertime heatwaves and unusually persistent patterns. This suggests that heatwaves do not necessarily require the continued flow of warm air over a region and that local effects could be important for their occurrence.
Nathaelle Bouttes, Fanny Lhardy, Aurélien Quiquet, Didier Paillard, Hugues Goosse, and Didier M. Roche
Clim. Past, 19, 1027–1042, https://doi.org/10.5194/cp-19-1027-2023, https://doi.org/10.5194/cp-19-1027-2023, 2023
Short summary
Short summary
The last deglaciation is a period of large warming from 21 000 to 9000 years ago, concomitant with ice sheet melting. Here, we evaluate the impact of different ice sheet reconstructions and different processes linked to their changes. Changes in bathymetry and coastlines, although not often accounted for, cannot be neglected. Ice sheet melt results in freshwater into the ocean with large effects on ocean circulation, but the timing cannot explain the observed abrupt climate changes.
Gaëlle Leloup and Didier Paillard
Earth Syst. Dynam., 14, 291–307, https://doi.org/10.5194/esd-14-291-2023, https://doi.org/10.5194/esd-14-291-2023, 2023
Short summary
Short summary
Records of past carbon isotopes exhibit oscillations. It is clear over very different time periods that oscillations of 400 kyr take place. Also, strong oscillations of approximately 8–9 Myr are seen over different time periods. While earlier modelling studies have been able to produce 400 kyr oscillations, none of them produced 8–9 Myr cycles. Here, we propose a simple model for the carbon cycle that is able to produce 8–9 Myr oscillations in the modelled carbon isotopes.
Davide Faranda, Stella Bourdin, Mireia Ginesta, Meriem Krouma, Robin Noyelle, Flavio Pons, Pascal Yiou, and Gabriele Messori
Weather Clim. Dynam., 3, 1311–1340, https://doi.org/10.5194/wcd-3-1311-2022, https://doi.org/10.5194/wcd-3-1311-2022, 2022
Short summary
Short summary
We analyze the atmospheric circulation leading to impactful extreme events for the calendar year 2021 such as the Storm Filomena, Westphalia floods, Hurricane Ida and Medicane Apollo. For some of the events, we find that climate change has contributed to their occurrence or enhanced their intensity; for other events, we find that they are unprecedented. Our approach underscores the importance of considering changes in the atmospheric circulation when performing attribution studies.
Flavio Maria Emanuele Pons and Davide Faranda
Adv. Stat. Clim. Meteorol. Oceanogr., 8, 155–186, https://doi.org/10.5194/ascmo-8-155-2022, https://doi.org/10.5194/ascmo-8-155-2022, 2022
Short summary
Short summary
The objective motivating this study is the assessment of the impacts of winter climate extremes, which requires accurate simulation of snowfall. However, climate simulation models contain physical approximations, which result in biases that must be corrected using past data as a reference. We show how to exploit simulated temperature and precipitation to estimate snowfall from already bias-corrected variables, without requiring the elaboration of complex, multivariate bias adjustment techniques.
Miriam D'Errico, Flavio Pons, Pascal Yiou, Soulivanh Tao, Cesare Nardini, Frank Lunkeit, and Davide Faranda
Earth Syst. Dynam., 13, 961–992, https://doi.org/10.5194/esd-13-961-2022, https://doi.org/10.5194/esd-13-961-2022, 2022
Short summary
Short summary
Climate change is already affecting weather extremes. In a warming climate, we will expect the cold spells to decrease in frequency and intensity. Our analysis shows that the frequency of circulation patterns leading to snowy cold-spell events over Italy will not decrease under business-as-usual emission scenarios, although the associated events may not lead to cold conditions in the warmer scenarios.
Gaëlle Leloup and Didier Paillard
Clim. Past, 18, 547–558, https://doi.org/10.5194/cp-18-547-2022, https://doi.org/10.5194/cp-18-547-2022, 2022
Short summary
Short summary
Over the last 2.6 Myr, the Quaternary period has been marked by the alternation of extended and reduced Northern Hemisphere ice sheets, known as glacial-interglacial cycles. With a simple model, we are able to reproduce the main features of the ice volume evolution, like the switch of periodicity, from 41 kyr cycles to 100 kyr cycles, observed in the data after 1 Ma. The quality of the model-data agreement depending on the input insolation and period considered is discussed.
Bérengère Dubrulle, François Daviaud, Davide Faranda, Louis Marié, and Brice Saint-Michel
Nonlin. Processes Geophys., 29, 17–35, https://doi.org/10.5194/npg-29-17-2022, https://doi.org/10.5194/npg-29-17-2022, 2022
Short summary
Short summary
Present climate models discuss climate change but show no sign of bifurcation in the future. Is this because there is none or because they are in essence too simplified to be able to capture them? To get elements of an answer, we ran a laboratory experiment and discovered that the answer is not so simple.
Cited articles
Andjel, E. D.: Invariant measures for the zero range process, Ann. Probabil., 525–547, 1982.
Balian, R.: Physique statistique et themodynamique hors équilibre, Ecole Polytechnique, 1992.
Billingsley, P.: Ergodic theory and information, Wiley, 1965.
Burda, Z., Duda, J., Luck, J. M., and Waclaw, B.: Localization of the maximal entropy random walk, Phys. Rev. Lett., 102, 160602, 2009.
Dewar, R. C. and Maritan, A.: A theoretical basis for maximum entropy production, in: Beyond the Second Law, 49–71, Springer, 2014.
Domb, C.: Phase transitions and critical phenomena, Vol. 19, Academic Press, 2000.
Frisch, U.: Turbulence: the legacy of AN Kolmogorov, Cambridge University Press, 1995.
Gómez-Gardeñes, J. and Latora, V.: Entropy rate of diffusion processes on complex networks, Phys. Rev. E, 78, 065102, 2008.
Großkinsky, S., Schütz, G. M., and Spohn, H.: Condensation in the zero range process: stationary and dynamical properties, J. Stat. Phys., 113, 389–410, 2003.
Herbert, C., Paillard, D., Kageyama, M., and Dubrulle, B.: Present and Last Glacial Maximum climates as states of maximum entropy production, Q. J. Roy. Meteorol. Soc., 137, 1059–1069, 2011.
Levine, E., Mukamel, D., and Schütz, G.: Zero-range process with open boundaries, J. Stat. Phys., 120, 759–778, 2005.
Martyushev, L. M. and Seleznev, V. D.: Maximum entropy production principle in physics, chemistry and biology, Phys. Rep., 426, 1–45, 2006.
Mihelich, M., Dubrulle, B., Paillard, D., and Herbert, C.: Maximum Entropy Production vs. Kolmogorov-Sinai Entropy in a Constrained ASEP Model, Entropy, 16, 1037–1046, 2014.
Monthus, C.: Non-equilibrium steady states: maximization of the Shannon entropy associated with the distribution of dynamical trajectories in the presence of constraints, J. Stat. Mech., p. P03008, 2011.
Murphy, J. M., Sexton, D. M., Barnett, D. N., Jones, G. S., Webb, M. J., Collins, M., and Stainforth, D. A.: Quantification of modelling uncertainties in a large ensemble of climate change simulations, Nature, 430, 768–772, 2004.
Onsager, L.: Reciprocal relations in irreversible processes. I., Phys. Rev., 37, 2265–2279, 1931.
Paltridge, G. W.: Global dynamics and climate-a system of minimum entropy exchange, Q. J. Roy. Meteorol. Soc., 101, 475–484, 1975.
Pascale, S., Gregory, J. M., Ambaum, M. H., and Tailleux, R.: A parametric sensitivity study of entropy production and kinetic energy dissipation using the FAMOUS AOGCM, Clim. Dynam., 38, 1211–1227, 2012.
Rotstayn, L. D.: On the "tuning" of autoconversion parameterizations in climate models, J. Geophys. Res.-Atmso. (1984–2012), 105, 15495–15507, 2000.
Troen, I. and Mahrt, L.: A simple model of the atmospheric boundary layer; sensitivity to surface evaporation, Boundary-Lay. Meteorol., 37, 129–148, 1986.
Turkington, B.: An optimization principle for deriving nonequilibrium statistical models of hamiltonian dynamics, J. Stat. Phys., 152, 569–597, 2013.
Wallace, J. M. and Hobbs, P. V.: Atmospheric science: an introductory survey, Vol. 92, Academic press, 2006.
