Large-scale Dynamics & Climate

At a fundmental level, I am driven by the desire to solve nature's puzzles. This at times takes me down a path of observations, and other times down purely theoretical paths. My research thus far has shown me that just because the experiment may be idealized (or very idealized!), it doesn't mean the results aren't applicable to the observed atmosphere. Often times, the simplest solution is the right one.

Ongoing research

Eddy-mean flow feedbacks

The jet-streams are large-scale westerlies that travel around the globe in both hemispheres and have large impacts on society. These rivers of air can shift around, bringing sunny weather to some cities and rainy weather to those in its path. This north-south shift of the midlatitude jets is known as the "annular mode", and sometimes these persistent shifts of the jet can lead to "blocking anticyclones". I am interested in how and why the jet shifts and "sticks" in one location more than others, and how the movements of the jet-stream may change with increased greenhouse gas concentrations.

We know that eddies play an important role in the feedback loop that maintains the jet-streams, and I am interested in better understanding the role of eddies in the real atmosphere. I use many tools to accomplish this, one of which is an incredibly simple model called a barotropic model: a single layer of fluid on a rotating sphere. Through Rossby-wave dynamics on the sphere, if we just stir the vorticity we can create zonal-jets as shown in the figures above. Believe it or not, this very simple model can tell us quite a bit about the real atmosphere! To show this, I try and relate results from the barotropic model to reanalyses data as well as comparing them to output from the most sophisticated climate models (e.g. CMIP3, CMIP5 archives).

Rossby wavebreaking

Part of my research has led me to investigate Rossby-wave breaking, which in part is how the eddies interact with the jet-streams. To do this, I have written an objective algorithm to find and follow wave-breaking events to give me a 4D map (time x pressure x latitude x longitude) of wave-breaking events. I have used this diagnostic to study influence of jet shifts on eddy-mean flow feedbacks, and plan to also use it to investigate the interaction between the stratospheric and the tropospheric circulations.

Moisture and the general circulation

Water vapor has huge importance for our atmosphere, as it is the major greenhouse gas, and is predicted to drastically change as the climate warms. I am interested in how changes in latent heat and atmospheric stability may affect the feedback between the eddies and the jet-streams. To do this, I am using a simplified moist GCM designed by Dr. Dargan Frierson that allows me to make the atmosphere wetter and drier without the radiation budget "seeing" the change so that I can study the dynamical effects on the general circulation.

Other Research in Civil Engineering & Ecology

As I made my way from particle physics to atmospheric science as an undergraduate, I spent two years acquainting myself with analysis techniques under Dr. Efi Foufoula-Georgiou in the Civil Engineering Dept. at the UofM. We collaborated with ecologists to use simple scaling techniques to try and predict algae concentrations in a California river network.

As part of my honors thesis, I also studied the dynamics of granular media with my colleague Daniel Beisang under the direction of Dr. Kimberly Hill. We shook thousands of metal beads back and forth using an earthquake simulator to investigate the sudden transition the beads went through from a random to lattice configuration.

Dec. 2006 - Mar. 2007: Granular media research under Dr. Kimberly Hill, professor of Civil Engineering of the University of Minnesota. Qualitatively described a horizontally vibrated granular media. This research was the subject of my honors thesis at the University of Minnesota.

Aug. 2006 - Dec. 2007: NCED research under Dr. Efi Foufoula-Georgiou, Co-Director of the National Center for Earth-surface Dynamics and Dr. Miki Hondzo, at St. Anthony Falls Laboratory, Minneapolis, MN. Upscaling algae dynamics from the small rock scale to the large scale of a watershed in collaboration with Dr. Mary Power, Director of the California Diversity Center at Berkeley. Results published in Geophysical Research Letters.