Dan Chavas

Hello!

News:

• We have open positions for a graduate student (MS/PhD; start Fall 2021) in hurricanes or severe thunderstorms and climate. Please email Dan (dchavas@purdue.edu) for more information and/or to ask any questions. I’d love to hear about your background and interests and let you know more about myself, our group, and our department. We need to increase participation from underrepresented groups in our field at every level -- individuals from any such group are especially encouraged to reach out to Dan to learn more.
• We need to talk openly about race and racism in academia. I've decided to start writing about it, including my own personal story.
• Dan has been awarded an NSF Faculty Early Career Development (CAREER) award! This is a 5-year award grant to study climate controls on the subtropical high and hurricane landfall risk, and to develop a weather and climate risk internship program to put atmospheric science graduates in positions to help use weather and climate information to make better decisions.
• I’m trying something new: short YouTube recorded presentations on content from recently published papers -- check out the Research page or go straight to my YouTube playlist of presentations. I spend so much time making nice engaging presentations for seminars, I might as well share them publicly.
• Exciting recent papers:
  • Can we define a steady environmental sounding supportive of severe convective storms based in the physics of a hydrostatic atmosphere? Yes, we have developed such a theoretical sounding using a static energy framework that has a variety of benefits over the widely-used Weisman and Klemp model.
  • Nature News and Views article, co-written with PhD student Jie Chen, on new Li and Chakraborty (2020) paper arguing that warming may cause hurricanes to last longer after landfall.
  • Could there be hurricanes on exoplanets that might support life? Yes, on Earth-like exoplanets that orbit close to weaker stars, which we have the best chance of observing with future space telescope technology. These "exo-hurricanes" are cool in their own right, but they also may loft water vapor high into the atmosphere, which could be detectable by remote sensing.
  • Does the outflow of an axisymmetric hurricane interact with its environment? Yes, and it generates inertial waves, whose restoring force is the inertial stability of the environment (in the radial direction). These waves induce thermally-indirect overturning circulations in the outer storm circulation, particularly for high-latitude storms, though they do not penetrate the eyewall and so do not affect the thermodynamic cycle of the strongest winds.
  • How does a mature hurricane respond to surface drying and roughening, forcings that are associated with landfall? While both surface drying and surface roughening ultimately cause a mature hurricane to weaken, the transient responses and physical mechanisms for each are very different. These findings indicate that the inland response of a hurricane after landfall may vary markedly depending on the local land surface properties. (Led by PhD student Jie Chen)
  • Could we fit more hurricanes on Earth in the present-day climate? Yes, the thermodynamic environment would allow an order of magnitude more storms than is currently observed each year. This suggests that the favorable parts of the climate system are not densely packed, and thus some other aspect of internal dynamics must limit the annual number of hurricanes globally. (Led by post-doc Kim Hoogewind)
  • What sets hurricane genesis rate and storm size vs. latitude? Aquaplanet experiments varying planetary rotation rate and radius show i) hurricane genesis rate exhibits a universal quasi-linear increase with the Coriolis parameter; ii) hurricane size scales with the Rhines scale (a new, better theory at long last!); and iii) the dynamics of rotating RCE on the f-plane (a widely-studied topic) can be fully generalized to the rotating sphere, thereby explaining what the "background" dynamical (i.e. absent any variability in thermodynamic forcing) behavior of hurricanes is on any rotating rocky planet. This work provides the foundation for understanding how thermodynamic variability on Earth acts to suppress/modify hurricane activity relative to this background, thermodynamically-uniform state.
  • Do hurricanes need water (or any condensible species) to exist? Hurricanes form and persist in dry and/or cold atmospheres (wild!).

About me:

I am currently Assistant Professor of Atmospheric Science at Purdue University in the Department of Earth, Atmospheric, and Planetary Sciences. My group is called the Climate and Extreme Weather Laboratory. We research the physics and impacts of extreme weather in our atmosphere, including hurricanes and tornadoes, and their dependence on climate. Here is a bit of insight into the philosophy behind our research.

Before starting at Purdue, I was an NSF Postdoctoral Research Fellow in Civil and Environmental Engineering at Princeton University, and I received my PhD in Atmospheric Science from MIT and B.S. in Atmospheric and Oceanic Sciences and Applied Mathematics at the University of Wisconsin-Madison. Between undergrad and grad school, I studied abroad in Montpellier, France, spent a summer as a volunteer teacher in Tamale, Ghana, interned at the World Meteorological Organization in Geneva, Switzerland, and worked as a research associate at the Joint Global Change Research Institute in College Park, MD while living in Washington DC. Before my post-doc I went on a beautiful 2-month road trip across the western U.S.. There's a lot outside of science that inspires me, from podcasts like Imaginary Worlds ("how we create them and why we suspend our disbelief") and 99% Invisible, and creative people like Antoni Gaudi, Donald Glover, Kishi Bashi, Andrew Bird, Lizzo, Lin-Manuel Miranda, Ali Wong, Dave Chappelle, Frank Lloyd Wright, Anthony Bourdain (RIP), and curious children everywhere. I talk about some of this in this Climate Scientists podcast episode with Dan Jones. My wife is Senior Lead Analyst at CB Insights, and we have a fearless toddler daughter named Maya. I'm ethnically ambiguous.