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Romain Fiévet

Department Service Climate Physics
Group SCLab Computational Infrastructure and Model Development Climate Surface Interaction
Position Research Scientist
phone
Email romain.fievet@mpimet.mpg.de
Room B 415

 

I am a research scientist with a background in computational fluid dynamics and aerospace engineering. Here at MPI, I specialize in storm-resolving climate modeling, cloud microphysics and hm-scale regional simulations. I work on the full research pipeline: from developping and running the ICON model, to processing and analyzing large complex datasets. By running at ever-refined spatio-temporal resolutions, I seek to understand how fine-scale atmospheric processes - such as cloud microphysics and turbulence - can, upon improved representation, reverse-cascade and ultimately feedback onto larger scales.

Google Scholar Profile: View complete publication list

Professional Network: LinkedIn

 

Work samples

Limited-area modelling for multiscale cloud physics

During summer 2024, the ORCESTRA (Organized Convection and EarthCARE Studies over the Tropical Atlantic) field campaign was launched to advance our understanding of the physical mechanisms governing mesoscale tropical convection organization. The campaign investigated how convective organization interacts with tropical waves and air-sea processes, and examined its broader implications for climate dynamics and Earth's radiation budget.

In parallel with the observational campaign, we conducted high-resolution numerical simulations using the storm-resolving ICON Limited Area Model in its Sapphire v1.0 configuration. These simulations employed explicit convection at kilometer-scale resolution, with high-frequency model outputs specifically designed to match the temporal sampling of ORCESTRA observations from dropsondes, radiosondes, and satellite-based radar measurements.

This coordinated approach allows for detailed model validation by comparing similarly-sampled observational and numerical datasets. By revealing the biases present in the model, this work contributes to improving it. Conversely, this work shows how storm-resolving models can be used on their own to investigate the physics of small-scale processes driving ITCZ multi-scale dynamics.

Global-nested simulations

Rather then run ICON over a limited-area domain, having to prescribe and construct imperfect boundary conditions, we can run the model with several domains at once, nested within a global mesh. This approach allows us to perform numerical experiments zoomin-in on any part of the global, while observing the effect of each mesh-refinement level.

Large-eddy simulations of cold pools

Convective cold pools (CPs) are regions of cool air forming beneath precipitating clouds. As rain droplets evaporate during their fall, they cool down the surrounding air, thereby increasing its weight and causing it to sink down. As the cold sinking airflow hits the ground, it spreads outward in all directions, creating strong wind gusts which are important mediators of the weather system. Indeed, such gust fronts can suppress cloud formation in some locations, by cooling the near-surface air, while simultaneously triggering cloud formation along their edges by wedging underneath and lifting the ambient air. Numerical weather models should ideally account for these effects. Unfortunately, the models' grid resolution is often too coarse to represent the thin CPs, and it is not yet known what resolution should be used. In this study, high-resolution simulations of idealized CPs are carried out at different mesh resolutions, from 800 to 25m, allowing a systematic exploration of CPs' sensitivity to grid resolution. Our simulation results may help reveal configuration requirements for high-resolution simulations and guide climate model development.

Peer-reviewed publications

Peer-reviewed publications:

  • Börner, R., Haerter, J. O. and Fiévet, R., Modeling wind-responsive diurnal sea surface temperature for cloud-resolving simulations, Geoscientific Model Development, Vol.18, No. 5, 2025
  • Kruse, I., Haerter, J. O. and Fiévet, R., Tipping to an Aggregated State by Mesoscale Convective Systems, Journal of Advances in Modeling Earth Systems, Vol. 17, No. 3, 2025
  • Höller, J., Fiévet, R. and Haerter, J. O., U-Net Segmentation for the Detection of Convective Cold Pools From Cloud and Rainfall Fields, Journal of Advances in Modeling Earth Systems, Vol. 129, No. 1, 2024
  • Höller, J., Haerter, J. O. and Fiévet, R., Cold Pool Detection and Track Algorithm, Journal of Advances in Modeling Earth Systems, Vol. 16, No. 1, 2024
  • Fiévet, R., Meyer, B. and Haerter, J. O., On the sensitivity of convective cold pools to mesh resolution, Journal of Advances in Modeling Earth Systems, Vol. 15, No. 8, 2023
  • Gruner G. J., Fiévet, R. and Haerter, J. O., The Diurnal Path to Persistent Convective Self-Aggregation, Journal of Advances in Modeling Earth Systems, Vol. 14, No. 5, 2022

Peer-reviewed mansucripts:

  • Cardesa, J. I., Fiévet, R., Deniau, H., Airiau and C., Piot, E., Optimizing an acoustic liner by automatic differentiation of a compressible flow solver, Journal of computational science, 2022
  • Fiévet, R., Deniau, H., Brazier J. P. and Piot, E., Numerical Analysis of Porous Coatings Stabilizing Capabilities on Hypersonic Boundary-Layer Transition, AIAA Journal, Vol. 59, No. 10, 2021
  • Fiévet, R., Deniau, H. and Piot, E., Strong compact formalism for characteristic boundary conditions with discontinuous spectral methods, Journal of Computational Physics, Vol. 408, 2020
  • Prakash, S., Fiévet, R. , Raman, V., Burr, J. and Yu, H. K., Analysis of the Detonation Wave Structure in a Linearized Rotating Detonation Engine, AIAA Journal, Vol. 58, No 12, 2020
  • Fiévet, R., Voelkel, S., Varghese, P. and Raman, V., Numerical investigation of vibrational relaxation coupling with turbulent mixing, Physical Review of Fluids, No. 4, 2019
  • Fiévet, R., Raman, V. and Auslender, A., Data-driven one-dimensional modeling of pseudoshocks, Journal of Propulsion and Power, Vol. 35, No. 2, 2019
  • Fiévet, R. and Raman, V., Effect of vibrational nonequilibrium on isolator shock structure, Journal of Propulsion and Power, Vol. 34, No. 5, 2018
  • Fiévet, R., Koo, H., Raman, V., Auslender, A., Numerical investigation of shock train response to inflow boundary layer variations, AIAA Journal, Vol. 55, No. 9, 2017
  • Fiévet, R., Voelkel, S., Koo, H., Raman, V. and Varghese, P., Effect of Thermal Nonequilibrium on Ignition in Scramjet Combustors, Proceeding of the Combustion Institute, Vol. 36, No. 2, 2017
  • Fiévet, R., Tinney, C.E., Baars, W.J., Hamilton, M.F., Coalescence in the sound field of a laboratory scale supersonic jet, AIAA Journal, Vol. 54, No. 1, 2015