Thibaut Dauhut

PhD in meteorology

Clouds above the beach

About me

Hi ! My name is Thibaut Dauhut.
I am a postdoctoral researcher at Max Planck Institute for Meteorology in Hamburg, Germany.
I study how deep convection transports air and water into the tropical lower stratosphere. This transport impacts the composition and the radiative properties of the stratosphere, both of key importance for the future of our climate. I work with cutting-edge Large-Eddy Simulations (LES), with resolutions as fine as 100 m. I investigate the small-scale processes (updrafts, low-level convergence, entrainment by cloud eddies, overshoots) that determine the capability of the very deep convective systems to hydrate the stratosphere.

In discussion

The_three_Atmospheric_Circulations

Convective hydrationin the tropical tropopause layer during the StratoClim aircraft campaign: Pathway of an observed hydration patch

Keun-Ok Lee, Thibaut Dauhut, Jean-Pierre Chaboureau, Sergey Khaykin, Martina Krämer and Christian Rolf

In discussion

The source and pathway of the hydration patch in the TTL (Tropical Tropopause Layer) that was measured during the StratoClim field campaign during the Asian summer monsoon in 2017, and its connection to convective overshoots are investigated.

The_three_Atmospheric_Circulations

Ice injected up to the Tropopause by Deep Convection: 1) in the AustralConvective Tropics

Iris-Amata Dion, Philippe Ricaud, Peter Haynes, Fabien Carminati and Thibaut Dauhut

In discussion

The impact of deep convection on the water budget (water vapor and ice) from the tropical Upper Troposphere(UT, around 146 hPa) to the Tropopause Level (TL, around 100 hPa) is investigated. Ice water content (IWC) and watervapour (WV) measured in the UT and the TL by the Microwave Limb Sounder (MLS, Version 4.2) are compared to theprecipitation (Prec) measured by the Tropical Rainfall Measurement Mission (TRMM, Version 007).

Publications

The_three_Atmospheric_Circulations

The Three Atmospheric Circulations over the Indian Ocean and the MaritimeContinent and Their Modulation by the Passage of the MJO

Daria Kuznetsova, Thibaut Dauhut and Jean-Pierre Chaboureau

Published on 28 November 2018

The passage of the Madden–Julian oscillation (MJO) over the Indian Ocean and the Maritime Continentis investigated during the episode of 23–30 November 2011. A Meso-NH convection-permitting simulationwith a horizontal grid spacing of 4 km is examined. The simulation reproduces the MJO signal correctly, showingthe eastward propagation of the primary rain activity.

Isentropic streamfunctions of very deep Hector using theta_s with and without precipitation

Reply to the Comments of Olivier Pauluis to the paper “A Third-Law Isentropic Analysis of a Simulated Hurricane”

Pascal Marquet and Thibaut Dauhut

Published on 10 August 2018

Detailed investigation of the moist-air entropy and its meaning for the atmospheric systems like the deep convective systems. The use of theta_s as a strict equivalent of the entropy is illustrated with the isentropic diagrams of Hector the Convector.

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Transport of tracers by one of the tallest updrafts of Hector

Giga-LES of Hector the Convector and Its Two Tallest Updrafts up to the Stratosphere

Thibaut Dauhut, Jean-Pierre Chaboureau, Juan Escobar and Patrick Mascart

Published on 7 December 2016

The updrafts inside Hector are identified using a clustering algorithm, that I developed to run on parallel supercomputers. Within more than 16 000 updrafts with vertical velocities larger than 10 m/s, only a dozen are 4-km tall. The two tallest only crontribute to more than 90% of the vertical mass flux across the tropical tropopause layer (TTL) and produce overshoots into the stratosphere.

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Isentropic Diagrams of vertical velocity and stream function

The Atmospheric Overturning Induced by Hector the Convector

Thibaut Dauhut, Jean-Pierre Chaboureau, Patrick Mascart and Olivier Paulius

Published on 20 September 2017

The overturning of Hector the Convector, a tropical multicellular convective system of northern Australia that regularly overshoots into the stratosphere, is synthesized at the scale of a large-eddy simulation. The isentropic analysis offers the advantage of filtering out the reversible motions due to gravity waves and taking into account the turbulent fluxes that contribute to the vertical transport. Two key circulations are charac- terized: the troposphere deep overturning and the mass exchange due to the overshoots into the stratosphere. The transition from deep to very deep convection is associated with a change in the diabatic tendency inside the tallest updrafts: the latent heat release due to the formation of a large amount of icy hydrometeors exceeds the loss of energy due to mixing with the drier, colder air of the environment.

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Overshooting Updraft in Large Eddy Simulation of Hector

Large-eddy simulations of Hector the convector making the stratosphere wetter

Thibaut Dauhut, Jean-Pierre Chaboureau, Juan Escobar and Patrick Mascart

Published on 12 September 2014

A series of large-eddy simulations (LES) were performed for a Hector thunderstorm observed on 30 November 2005 over the Tiwi Islands. On that day, ice particles reaching 19-km altitude were measured. The LES developed overshooting updrafts penetrating the stratosphere that compared well with observations. While moistening appeared to be robust with respect to the grid spacing used, grid spacing on the order of 100 m may be necessary for a reliable estimate of hydration.

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Example of drifter trajectory off the Brazilian shore

Near-inertial motions in the Brazil Current at 24°S-36°S: Observations by satellite tracked drifters

Arcilan T. Assireu, Thibaut Dauhut, Francisco A. dos Santos and João A. Lorenzzetti

Published on 12 July 2017

I did a one-year intership at the research institute for the natural ressources of the Federal University of Itajuba, Brazil. During this period I characterised the near inertial currents (NICs) in the ocean and their link with the synoptic weather conditions. All my results are presented in this study. I used the trajectories from drifters to examine motions in the inertial frequency band. The atmospheric conditions were favorable to NICs generations: the wind stress rotary spectrum is anticyclonically polarized with a near-inertial peak. In the ocean, a large increase in the eddy kinetic energy is found in the f band south of 28°S. The predominance of NICs south of 28°S appears to be related to the Effective Coriolis Frequency.

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Forecast of dust emission in Sahel region

Fennec dust forecast intercomparison over the Sahara in June 2011

Jean-Pierre Chaboureau, Cyrille Flamant, Thibaut Dauhut, Cécile Kocha, Jean-Philippe Lafore, Chistophe Lavaysse, Fabien Marnas, Mohamed Mokhtari, Jacques Pelon, Irene Reinares Martínez, Kerstin Schepanski, and Pierre Tulet

Published on 7 June 2016

The clustering algorithm, that I developed to run on parallel computers, can be used to identify any 2-D or 3-D meteorological strucutre. Here a nice example with the identification of the wind regimes over Africa, that latter lead to dust emission. Beside the harmattan (HRM), the cold pools (CPL) below some convective systems contribute to the observed large near-surface dust concentrations.

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3D visualisation of Hector the Convector simulated with a MesoNH GigaLES

Overview of the Meso-NH model version 5.4 and its applications

Christine Lac and co-authors

Published on 29 May 2018

The reference description of the tool I use to produce simulations: the non-hydrostatic atmospheric model Meso-NH.

Contact

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Max Planck Institut für Meteorologie
Bundesstraße 53
20146 Hamburg
GERMANY

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