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Caroline Muller
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My research interests lie in the fields of geophysical fluid dynamics and climate science. I am particularly interested in the study of small-scale processes in the atmosphere and in the oceans, which play an important role in the large-scale climate.
Important examples that I work on are internal waves in the oceans, and clouds in the atmosphere. Despite their small scales, these processes can significantly affect the large scales. Notably, internal waves can impact ocean water masses, and thus the global ocean circulation, through the transport of energy and momentum. The global ocean circulation is not only a fascinating topic, but it is also a crucial ingredient of our climate. And clouds can impact the large-scale energy balance of our planet, and thus our global climate, though their interaction with atmospheric radiation. Clouds are also closely related to the water cycle, and thus the precipitation distribution, with important societal impacts.
The overall goal of my research activities is to improve our fundamental understanding of these small-scale processes and of the relevant physical processes. To that end, I use theoretical and numerical models, from idealized high-resolution simulations to global global climate models in realistic configuration.
Important examples that I work on are internal waves in the oceans, and clouds in the atmosphere. Despite their small scales, these processes can significantly affect the large scales. Notably, internal waves can impact ocean water masses, and thus the global ocean circulation, through the transport of energy and momentum. The global ocean circulation is not only a fascinating topic, but it is also a crucial ingredient of our climate. And clouds can impact the large-scale energy balance of our planet, and thus our global climate, though their interaction with atmospheric radiation. Clouds are also closely related to the water cycle, and thus the precipitation distribution, with important societal impacts.
The overall goal of my research activities is to improve our fundamental understanding of these small-scale processes and of the relevant physical processes. To that end, I use theoretical and numerical models, from idealized high-resolution simulations to global global climate models in realistic configuration.
THE HYDROLOGICAL CYCLE AND CLIMATE CHANGE
Precipitation extremes, both wet
(floods) and dry (deserts), have many societal impacts. I investigate
how precipitation extremes respond to warming using a cloud-resolving
model (see Publications for more details).
The figure below shows a snapshot from the cloud-resolving model. The colors represent the surface temperature, and the white contours are isosurfaces of condensate amounts (liquid and ice). Understanding the response of the hydrological cycle to climate change is a major challenge, and the subject of intense research.
The figure below shows a snapshot from the cloud-resolving model. The colors represent the surface temperature, and the white contours are isosurfaces of condensate amounts (liquid and ice). Understanding the response of the hydrological cycle to climate change is a major challenge, and the subject of intense research.
Snapshot from a cloud-resolving simulation (click on it for a movie)
THE ORGANIZATION OF CONVECTION IN HIGH-RESOLUTION SIMULATIONS
Tropical
convection
can organize on a wide range of scales, but the physical processes
behind this organization are still unclear. Several studies using
high-resolution cloud-resolving models point out the tendency of
atmospheric convection to self-aggregate when the domain is large
enough. This self-aggregated state is a spatially organized atmosphere
composed of two large areas: a moist area with intense convection, and
a dry area with strong radiative cooling. I used a cloud-resolving
model to investigate in detail the onset of self-aggregation (see
Publications for more details).
The figure below shows a snapshot from the cloud-resolving model. The small-domain run (top panel) has reached radiative convective equilibrium. The large-domain run (bottom panel) looks quite different; convection spontaneously aggregates, eventually leading to an atmospheric state with one convectively active moist region surrounded by very dry air.
The figure below shows a snapshot from the cloud-resolving model. The small-domain run (top panel) has reached radiative convective equilibrium. The large-domain run (bottom panel) looks quite different; convection spontaneously aggregates, eventually leading to an atmospheric state with one convectively active moist region surrounded by very dry air.
THE DISSIPATION OF INTERNAL TIDES AND THE OCEANIC CIRCULATION
Internal tides are internal waves generated by the interaction of tidal
currents with deep-ocean topography. Their dissipation through wave
breaking and concomitant three-dimensional turbulence contributes to
vertical mixing in the deep ocean, and hence could play a role in the
large-scale ocean circulation.
I investigate the instability and dissipation of the internal tides, and the induced abyssal mixing (see Publications for more details).
I investigate the instability and dissipation of the internal tides, and the induced abyssal mixing (see Publications for more details).
Internal tides generated by a tidal current interacting with the
seafloor (shown at the bottom in gray) (click on it for a movie)
seafloor (shown at the bottom in gray) (click on it for a movie)