Associate Research Scholar
Program in Atmospheric and Oceanic Sciences
300 Forrestal Road
Princeton, New Jersey 08540
Email: caroline.muller at noaa.gov
My research interests lie in the fields of geophysical fluid dynamics and climate science. I am particularly interested in the study of processes which are too small in space and time to be explicitly resolved in coarse-resolution General Circulation Models (GCMs) used for climate prediction.
Important examples that I have worked on are internal wave breaking in the ocean and cloud processes in the atmosphere. These subgrid-scale processes need to be parametrized in GCMs in order to improve current model projections of climate change.
THE ORGANIZATION OF CONVECTION IN HIGH-RESOLUTION SIMULATIONS:
It is well known that convection can organize on a wide range of scales. 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. In recent work, we used a cloud-resolving model to investigate in detail the onset of self-aggregation (see Publications for more details).
The figure below (click on it for a movie) 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 HYDROLOGICAL CYCLE AND CLIMATE CHANGE:
Precipitation extremes, both wet (floods) and dry (deserts), have many societal impacts. In recent work, we used a cloud-resolving model to investigate how precipitation extremes respond to warming (see Publications for more details).
The figure below (click on it for a movie) 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 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).
C.J. Muller, 2013
Impact of convective organization on the response of tropical precipitation extremes to warming
Journal of Climate, in press
C.J. Muller, I.M. Held, 2012
Detailed investigation of the self-aggregation of convection in cloud-resolving simulations
Journal of the Atmospheric Sciences, 69, 2551?2565
C.J. Muller, P.A. O’Gorman, 2011
An energetic perspective on the regional response of precipitation to climate change
Nature Climate Change, 1, 266?271 doi:10.1038/nclimate1169 – Supplementary Material
C.J. Muller, P.A. O’Gorman, L.E. Back, 2011
Intensification of precipitation extremes with warming in a cloud resolving model
Journal of Climate, 24, 2784?2800 doi: 10.1175/2011JCLI3876.1
P.A. O’Gorman, C.J. Muller, 2010
How closely do changes in surface and column water vapor follow Clausius-Clapeyron scaling in climate-change simulations?
Environmental Research Letters, 5, 025207
See ERL news article about this paper
V.M. Canuto, A.M. Howard, Y. Cheng, C.J. Muller, A. Leboissetier and S.R. Jayne, 2010
Ocean turbulence III: New GISS vertical mixing scheme
Ocean Modelling, 34, 70-91
C.J. Muller, L.E. Back, P.A. O’Gorman, and K.A. Emanuel, 2009
A model for the relationship between tropical precipitation and column water vapor
Geophysical Research Letters, 36, L16804
Chosen to be an editor’s highlight
C.J. Muller and O. Buhler, 2009
Saturation of the internal tides and induced mixing in the abyssal ocean
Journal of Physical Oceanography, 39, 2077-2096
O. Buhler and C.J. Muller, 2007
Instability and focusing of internal tides in the deep ocean
Journal of Fluid Mechanics, 588, 1-28
Muller, C.J., 2008
Wave-induced mixing above the abyssal seafloor
Ph.D. Thesis, New York University