A5009596619- Tropical and Extratropical Cyclones Research
- Geomagnetism and Paleomagnetism Studies
- Climate variability and models
- Solar and Space Plasma Dynamics
- Oceanographic and Atmospheric Processes
- Geophysics and Gravity Measurements
- Meteorological Phenomena and Simulations
- Ocean Waves and Remote Sensing
- Coastal and Marine Dynamics
- Geology and Paleoclimatology Research
- Planetary Science and Exploration
- Nonlinear Dynamics and Pattern Formation
- Geological formations and processes
- Fluid dynamics and aerodynamics studies
- Fluid Dynamics and Turbulent Flows
- Fluid Dynamics and Thin Films
- Methane Hydrates and Related Phenomena
- Ionosphere and magnetosphere dynamics
- Wind and Air Flow Studies
- Geophysical and Geoelectrical Methods
- Precipitation Measurement and Analysis
- Magnetic and Electromagnetic Effects
Centre National de la Recherche Scientifique
2012-2024
Laboratoire atmosphères, milieux, observations spatiales
2020-2024
Sorbonne Université
2012-2024
Université de Versailles Saint-Quentin-en-Yvelines
2020-2024
Sorbonne Paris Cité
2022
Institut Pierre-Simon Laplace
2020-2021
Université Paris-Saclay
2020
École Normale Supérieure - PSL
2013-2018
Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères
2017
Laboratoire de Météorologie Dynamique
2012
This article describes the first results obtained from Surface Waves Investigation and Monitoring (SWIM) instrument carried by China France Oceanography Satellite (CFOSAT), which was launched on October 29, 2018. SWIM is a Ku-band radar with near-nadir scanning beam geometry. It designed to measure spectral properties of surface ocean waves. First, good behavior illustrated. then shown that nadir products (significant wave height, normalized cross section, wind speed) exhibit an accuracy...
State of the art numerical models Geodynamo are still performed in a parameter regime extremely remote from values relevant to physics Earth's core. In order establish connection between dynamo modeling and geophysical motivation, {it is necessary use} scaling laws. Such laws dependence essential quantities (such as magnetic field strength) on measured or controlled quantities. They allow for direct confrontation advanced with {constraints}. (...) We show that previous empirical strength...
Abstract This study examines 40 years of monthly precipitation data in Senegal (1979–2018) using Climatic Research Unit observations and ERA5 reanalyzes, aiming to understand the influence oceanic atmospheric factors on Senegal's July, August September (JAS). The variability is first compared with that broader Sahel region: although they share a significant portion their variance, appears more closely related Northeastern Tropical Atlantic (NETA) Sea Surface Temperature (SST). A detailed...
Abstract The motion of surface depressions evolving in a background meandering baroclinic jet is investigated using two-layer quasigeostrophic model on beta plane. Synoptic-scale finite-amplitude cyclones are initialized the lower and upper layer to south configuration favorable their interaction. lower-layer cyclone shown move across axis from its warm-air cold-air side. It presence poleward-oriented barotropic potential vorticity (PV) gradient that makes possible cross-jet through...
We investigate the transition from steady dipolar to reversing multipolar dynamos. The Earth has been argued lie close this transition, which could offer a scenario for geomagnetic reversals. show that between and dynamos is characterized by three terms balance (as opposed usually assumed two balance), involves non-gradient parts of inertial, viscous Coriolis forces. introduce equilibrium sole parameter ${\rm Ro}\,{\rm E}^{-1/3} \equiv {\rm Re}\,{\rm E}^{2/3}$, accurately describes wide...
In dynamo power-based scaling laws, the power $P$ injected by buoyancy forces is measured a so-called flux-based Rayleigh number, denoted as ${\rm Ra}_Q^*$ (see Christensen and Aubert, 2006). Whereas it widely accepted that this parameter (as opposite to controlled) in dynamos driven differential heating, literature much less clear concerning its nature case of imposed heat flux. We clarify issue highlighting case, Ra}_{Q}^*$ becomes controlled only limit large Nusselt numbers (${\rm Nu} \gg...
In addition to the weak-dipolar state and fluctuating-multipolar state, widely discussed in literature, a third regime has been identified Dormy (2016). It corresponds strong-dipolar branch which appears approach, numerically affordable regime, magnetostrophic limit relevant dynamics of Earth's core. We discuss transitions between these states point relevance this Geodynamo modelling.
Numerical studies of convection driven dynamos in rotating spherical shells exhibit a transition from steady dipolar to reversing multipolar as the forcing is increased. The dipolar-multipolar has so far been characterized using purely hydrodynamic parameters (Christensen and Aubert, Geophys. J. Int. 2006, 166, 97–114, Soderlund et al., Earth Planet. Sci. Lett. 2012, 333–334, 9–20, Oruba Dormy, Res. 2014, 41, 7115–7120). Motivated by these earlier descriptions, we investigate transitions...
Abstract The present paper provides a rationale for the regeneration stage undergone by surface cyclones when they cross baroclinic jet from its anticyclonic-shear (warm) side to cyclonic-shear (cold) in two-layer quasigeostrophic model. To do so, evolution of finite-amplitude synoptic various zonal flows is analyzed. Baroclinic with uniform horizontal shears are first considered. While anticyclonic shear allows much more efficient and sustainable extraction potential energy than cyclonic...
Abstract The combined effects of the deformation (horizontal stretching and shearing) nonlinearities on beta drift midlatitude cyclones are studied using a barotropic quasigeostrophic model plane. It is found that, without any background flow, cyclonic vortex moves more rapidly northward when it initially strongly stretched along mostly north–south direction. This meridional efficient at forming an anticyclone to east cyclone through Rossby wave radiation. cyclone–anticyclone couple then...
We consider rotating convection in a shallow, cylindrical domain. examine the conditions under which resulting vortex develops an eye at its core; that is, region where poloidal flow reverses and angular momentum is low. For simplicity, we restrict ourselves to steady, axisymmetric flows Boussinesq fluid. Our numerical experiments show that, such systems, forms as passive response development of so-called eyewall, conical annulus intense, negative azimuthal vorticity can form near axis...
Large scale cyclonic vortices, such as tropical cyclones in the Earth atmosphere, exhibit an eye their center. A new mechanism to understand formation of eyes is investigated. Contrary standard explanations, it shown that a purely hydrodynamic instability can yield eye.
Abstract This study focuses on ocean waves impacting the Moorea Island in French Polynesia, where coral reefs play an essential role biodiversity and protection of habitations. We investigate how innovative Surface Waves Investigation Monitoring (SWIM) instrument Chinese‐French Oceanography SATellite satellite enables to document a multi‐annual basis, spectral properties reaching coasts Island. Our analysis is based comparisons with situ measurements (wave gauges deployed outer slope reef),...
A comprehensive study of the classical linear spin-down a constant density viscous fluid (kinematic viscosity \nu) rotating rapidly (angular velocity \Omega) inside an axisymmetric cylindrical container (radius L, height H) with rigid boundaries, that follows instantaneous small change in boundary angular at Ekman number $E=\nu/H^2\Omega \ll 1$, was provided by Greenspan & Howard (1963). $E^{1/2}$-Ekman layers form quickly triggering inertial waves together dominant quasi-geostrophic (QG)...
ABSTRACT The effect of Tropical Cyclone Oli (2010) on the ocean is investigated using a variety measurements. In situ temperature measurements cyclone track are available via Centre de Recherches Insulaires et Observatoire l’Environnement (CRIOBE) array probes. This reflects an extreme fluctuation some 18 h after cyclone, lasting only 12 and exceeding 3°C in amplitude. study interprets this terms enhanced mixing associated with time-dependent inertial currents due to cyclonic winds. authors...
We investigate the ocean wave field under Hurricane SAM (2021). Whilst measurements of waves Tropical Cyclones (TCs) are rare, an unusually large number quality in situ and remote available that case. First, we highlight good consistency between spectra provided by Surface Waves Investigation Monitoring (SWIM) instrument onboard China-France Oceanography Satellite (CFOSAT), measured National Data Buoy Center (NDBC) buoys, a saildrone. The impact strong rains on SWIM is then further...
Abstract We investigate the mechanism for eye formation in hurricane-like vortices, using a formulation adapted from Oruba, Davidson, and Dormy. Numerical simulations are performed an axisymmetric model of dry rotating Rayleigh–Bénard convection under Boussinesq approximation. The fluxes heat momentum at sea surface described bulk aerodynamic formula. A simplified radiative cooling is also implemented. find that introduced Oruba et al., relying on vorticity stripping boundary layer, robust...
Abstract We investigate the ocean wave field under Hurricane Sam (2021). Whilst measurements of waves Tropical Cyclones are rare, an unusually large number quality in situ and remote available that case. First, we highlight good consistency between spectra provided by Surface Waves Investigation Monitoring (SWIM) instrument onboard China‐France Oceanography SATellite, measured National Data Buoy Center buoys, a saildrone. The impact strong rains on SWIM is then further investigated. show...
In a previous paper, Oruba, Soward & Dormy (J.Fluid Mech., vol.818, 2017, pp.205-240) considered the primary quasi-steady geostrophic (QG) motion of constant density fluid viscosity $\nu$ that occurs during linear spin-down in cylindrical container radius $L$ and height $H$, rotating rapidly (angular velocity $\Omega$) about its axis symmetry subject to mixed rigid stress-free boundary conditions for case $L=H$. Here, Direct Numerical Simulation (DNS) at large $L= 10 H$ Ekman number...
This study examines 40 years of monthly precipitation data in Senegal (1979-2018) using CRU observations and ERA5 reanalyses, aiming to understand the influence oceanic atmospheric factors on Senegal’s July, August September (JAS). Comparing variability with broader Sahel region, it emerges that is more closely associated Northeastern Tropical Atlantic (NETA) Sea Surface Temperature (SST). The increased linked northward shift InterTropical Convergence Zone (ITCZ), consistent numerous...