Dr. rer. nat. Masoud Rostami

Rostami

Masoud Rostami has significantly focused his research on climate modeling and atmospheric dynamics, particularly contributing to the construction of the atmosphere model Aeolus 2.0 as a component of the Potsdam Earth Model (POEM). The dynamical core of Aeolus 2.0 is a pseudo-spectral multi-layer moist-convective Thermal Rotating Shallow Water (mcTRSW) atmosphere model. With a PhD from Sorbonne University (formerly UPMC), Laboratoire de Météorologie Dynamique (LMD), he continues to serve as a guest scientist at LMD.

Some highlighted scientific activities, publications, and innovations include:

1. New Theory for MJO’s Dynamics: He introduced a novel theory explaining the genesis and behavior of the Madden-Julian Oscillation (MJO). According to this theory, an eastward-propagating MJO-like structure can be generated in a self-sustained and self-propelled manner due to nonlinear relaxation (adjustment) of a large-scale positive buoyancy anomaly, depressed anomaly, or a combination of these, as soon as this anomaly reaches a critical threshold in the presence of moist convection at the Equator. This anomaly, when reaching a critical threshold in the presence of moist convection at the Equator, leads to the formation of a convectively coupled "hybrid structure" with a "quasi-equatorial modon" and a convectively coupled baroclinic Kelvin wave (BKW). Interaction of the BKW with a new large-scale buoyancy anomaly contributes to the recurrent generation of the next cycle of MJO-like structure.

Rostami, M., Zhao, B., Petri, S., On the genesis and dynamics of Madden-Julian oscillation-like structure formed by equatorial adjustment of localized heating, Quarterly Journal of the Royal Meteorological Society, 2022, 148 (749), 3788-3813, https://doi.org/10.1002/qj.4388.

Rostami, M. and Zeitlin, V., Can geostrophic adjustment of baroclinic disturbances in tropical atmosphere explain MJO events?, Quarterly Journal of the Royal Meteorological Society, 2020, 146: 3998– 4013, doi: 10.1002/qj.3884, https://doi.org/10.1002/qj.3884.

2. Discovery of Adjusted Equatorial Modons: His research on eastward propagating structures led to the discovery of coherent, non-linear Equatorial Modons—steady, long-living, slowly eastward-moving, large-scale twin cyclones in the equatorial beta-plane. This discovery offers new insights into the large-scale dynamics of the tropical atmosphere, particularly the dynamical backbone of the Madden-Julian Oscillation (MJO). The findings suggest that vorticity, rather than divergence, plays a dominant role in the MJO.

Rostami, M., and Zeitlin, V., Eastward-moving convection-enhanced modons in shallow water in the equatorial tangent plane, Physics of Fluids, 2019, 31, 021701,  doi: 10.1063/1.5080415, https://doi.org/10.1063/1.5080415.

Rostami, M., and Zeitlin, V., Eastward-moving Equatorial Modons in Shallow-Water Models of the Tropical Atmosphere, Geophysical & Astrophysical Fluid Dynamics, 2020, 115:3, 345-367, doi: 10.1080/03091929.2020.1805448, https://doi.org/10.1080/03091929.2020.1805448.

3. Aeolus 2.0: A New Generation of Atmospheric Model: The development of the Aeolus 2.0  atmospheric model marks a significant leap forward in the field of atmospheric science. The model's dynamic core is built upon a novel multi-layer pseudo-spectral moist-convective Thermal Rotating Shallow Water (mcTRSW) model, enabling the consistent incorporation of horizontal variations in material properties. In contrast to classical shallow-water models, which assume a homogeneous, incompressible fluid under hydrostatic balance, Aeolus 2.0's inhomogeneous layers allow for variations in mean temperature and density gradients. Recently, the conceptual multi-layer version of the model has been employed to propose a novel theory for the genesis and dynamics of the Madden-Julian Oscillation (MJO), a prominent atmospheric phenomenon.

The link to the ZENODO repository for the open-source stand-alone version of the Atmospheric Model Aeolus 2.0 is provided below: [ZENODO Link]

4. Improved Moist Convective Rotating Shallow Water Model (imcRSW): This output presents an updated version of the idealized moist convective RSW model, referred to as the imcRSW model. This model incorporates various diabatic effects through appropriate parameterizations, including surface evaporation, condensation, latent heat release, tracer fields, precipitable water, and vaporization and entrainment. The imcRSW model has demonstrated successful applications in simulating tropical cyclones and polar vortices on both Earth and Mars. It is a robust and efficient model that maintains simplicity while accounting for diabatic effects. The model employs well-balanced numerical schemes and is capable of resolving fronts and capturing shocks. This feature enables researchers to explore fundamental characteristics of moist-convectively coupled synoptic-scale structures on Earth and other planets within a relatively short computational timeframe. The imcRSW model has been utilized to investigate the impact of moist convection on the instability of barotropic large-scale cyclonic and anticyclonic vortices on various planetary planes, including the f -plane, gamma-plane, and beta-plane.

Rostami, M., and Zeitlin, V., An improved moist-convective rotating shallow water model and its application to instabilities of hurricane-like vortices, Quarterly Journal of the Royal Meteorological Society, 2018, 1-13. doi: 10.1002/qj.3292, https://doi.org/10.1002/qj.3292.

5. Dynamical Nature of Saturn’s North Polar Hexagon: “On the dynamical nature of Saturn’s North Polar hexagon” is another research that has garnered scientific and public attention. In this research an innovative method is proposed to explain hexagon’s instability and to reproduce its structure, which is one of the enigmatic structures in the universe and has raised many open questions for more than three decades. Stability of the hexagonal shape for a few decades, its dependency on Saturn’s North polar vortex, and lack of a similar pattern on the Saturn’s South Pole are explained in this article. All dynamical variables of the large scale Saturn’s atmosphere are nondimensionalized by just one single parameter of Rossby deformation radius. Reproduction of hexagon by barotropic model, for the first time, and clarifying its dynamics help scientists to better understand the atmospheric circulation of Saturn and spatial distribution of passive tracers. Applying the same methodology on other planets is straight forward.

Rostami, M., and Zeitlin, V., and Spiga, A., On the dynamical nature of Saturn’s North Polar hexagon, Icarus, 2017, 297, 59-70, doi: org/10.1016/j.icarus.2017.06.006, https://doi.org/10.1016/j.icarus.2017.06.006.

6. Spatially Inhomogeneous CO2 Deposition in Mars’ Atmosphere: In this study, a new mechanism for explaining spatially inhomogeneous diabatic effects in the atmosphere of Mars has been proposed. Specifically, it involves the inhomogeneous deposition of CO2 through a gas-solid phase transition. This mechanism suggests that aerosol nuclei could trigger CO2 ice nucleation, leading to the formation of high potential vorticity blobs within Mars’ annular polar vortex. This study also introduces a parameterization to replicate and elucidate the generation of these vortices.

Rostami, M., and Zeitlin, V., Montabone, L., On the role of spatially inhomogeneous diabatic effects
upon the evolution of Mars’ annular polar vortex, Icarus, 2018, 314, 376-388, doi: 10.1016/j.icarus.2018.05.02, https://doi.org/10.1016/j.icarus.2018.05.026.


7. Equatorial Modon Genesis & Non-Universality of the Gill’s Mechanism: An innovative method has been initiated to generate the recently discovered Equatorial Modon (item 2) by adjusting the equatorial moist convective environment. This study offers new perspectives on the generation and dynamics of large-scale equatorial excited systems during equatorial adjustment over the warm pool.

The non-universality of the Gill mechanism is a significant breakthrough in understanding tropical circulation. The classical Gill theory, explaining the generation of Rossby and Kelvin waves due to a localized heating, was widely accepted as a universal mechanism. However, our recent studies have shown that the emergence of the "Equatorial Modon" can occur through geostrophic adjustment of a large-scale depression-type disturbance on the equatorial beta-plane. This finding provides new insights into equatorial excited systems and offers avenues for further research on tropical circulation.

Rostami, M., and Zeitlin, V., Geostrophic adjustment on the equatorial beta-plane revisited, Physics of Fluids, 2019, 31, 081702, doi: 10.1063/1.5110441, https://doi.org/10.1063/1.5110441.


8. Numerical Model for Modern Human Dispersal by Environmental, Cultural, and Societal Drivers: The development of two new human mobility/dispersal models, in collaboration with the interdisciplinary CRC806 project, represents a significant advancement in our understanding of the environmental, cultural, and societal drivers of human migration. These models, the Constrained Random Walk (CRW) models, have been applied to a range of time periods, from Heinrich events to the Holocene, and have been used to analyze the dispersal patterns of different technocomplexes. By taking into account both environmental factors and cultural/social influences, these models provide a more comprehensive understanding of the drivers of human migration and offer insights into how these factors have shaped human societies throughout history. The CRC806 project’s interdisciplinary approach highlights the importance of collaboration across fields in advancing our knowledge of complex societal issues. Indeed, this research aimed to simulate the interstadial and stadial periods of climate oscillations, specifically the Heinrich and Dansgaard-Oeschger (DO) events, which are believed to be caused by episodic discharge of massive numbers of icebergs from the Hudson Strait region into the North Atlantic Ocean. The study uses the CCSM4 climate model to better understand the potential for human existence during the early and late phases of the Aurignacian technocomplex, which occurred during these periods.

Shao, Y., Limberg, H., Klein, K., Wegener, C., Schmidt, I., Weniger, G. C., Hense, A., Rostami, M., Human-existence probability of the aurignacian techno-complex under extreme climate conditions,
Quaternary Science Reviews, 2021, 263, 106995, https://doi.org/10.1016/j.quascirev.2021.106995.

Klein, K., Wegener, C., Schmidt, I., Rostami, M., Ludwig, P., Ulbrich, S., Weniger,G. C., Shao, Y.,  Human Existence Potential during the Last Glacial Maximum, Quaternary International, , 2020, doi: 10.1016/j.quaint.2020.07.046.

9. Analyzing Hurricane-like Vortices: Insights from Barotropic and Baroclinic Linear Stability Analysis: This study delves into the dynamics of hurricane-like vortices and conducts barotropic and baroclinic linear stability analysis using Chebyshev grid points. The investigation spans one- and two-layer shallow water models, with a particular focus on various atmospheric phenomena including Saturn’s north polar vortex, the hexagonal circumpolar jet on Saturn, Mars’ annular polar vortex, Earth cyclonic structures, and the African Easterly Jet. The research undertaken sheds light on the evolution of hurricane-like vortices and their trajectories, including their interactions with diverse topographies such as elliptical islands, zonal and meridional mountainous ridges on the beta-plane.

Rostami, M. and Zeitlin, V., Evolution of double-eye wall hurricanes and emergence of complex tripolar end states in moist-convective rotating shallow water model, Physics of Fluids, 2022, 32, 066602, https://doi.org/10.1063/5.0096554.

Rostami, M., and Zeitlin, V., Evolution, propagation, and interactions with topography of hurricane-
like vortices in moist-convective rotating shallow-water model, Journal of Fluid Mechanics, 2020, 902, A24. doi: 10.1017/jfm.2020.567, https://dx.doi.org/10.1017/jfm.2020.567.

Rostami, M., and Zeitlin, V., Influence of condensation and latent heat release upon barotropic
and baroclinic instabilities of vortices in a rotating shallow water f-plane model, Geophysical &
Astrophysical Fluid Dynamics, 2017, 111 (1), 1–31, doi: 10.1080/03091929.2016.1269897, https://doi.org/10.1080/03091929.2016.1269897.


10. Natural versus anthropogenic pollution sources of insoluble precipitation residues: This set of studies has focused on the distribution, concentration, and isotopic composition of insoluble precipitation residues, trace elements such as Sr, Nd, and Pb, as well as atmospheric deposition and contamination of heavy metal elements in glacier depositions in the northeastern Tibetan Plateau region. To access the publication list, please refer to the complete list of publications.

11. Dynamics of extreme heatwaves in the mid-latitude atmosphere: This study examines the influence of large-scale localized temperature anomalies in mid-latitude regions on condensation patterns and corresponding circulation in various environments. The research reveals that these anomalies give rise to distinct circulation patterns and heat fluxes. Depending on the perturbation’s characteristics, they can induce atmospheric instability, leading to precipitation systems such as rain bands and distinctive cloud patterns. The study also demonstrates the initiation of an anticyclonic high-pressure rotation in the upper troposphere, resulting in an anisotropic northeast-southwest tilted circulation of heat flux.

Rostami, M., Severino, L., Petri, S., Hariri, S., Dynamics of Localized Extreme Heatwaves in the
Mid-Latitude Atmosphere: A Conceptual Examination, Atmospheric Science Letters, 2023, 25 (1),
e1188, https://doi.org/10.1002/asl.1188.

Contact

Potsdam Institute for Climate Impact Research (PIK)
rostami[at]pik-potsdam.de
P.O. Box 60 12 03
14412 Potsdam

ORCID

Publications

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