IMAGe Brown Bag- Changes in extreme precipitation with warming: A physical approach

05/06/2016 - 12:00pm to 1:00pm

Angeline Pendergrass
CIRES Visiting Fellow, University of Colorado

Determining how precipitation, especially extreme precipitation, has and will change with warming is an important challenge in climate science. In order to accomplish this, we need to develop a robust understanding of how to quantify extreme precipitation, its change, and the associated uncertainty. But we must also address why these changes occur, and describe the physical drivers of how precipitation can change. I hope that this talk can help contribute to discussion about how to integrate physical and statistical approaches to studying precipitation extremes.

I will share some work which takes a physical approach to understanding changes in precipitation and its extremes. In the global mean, precipitation is in balance with radiative and sensible heat flux components of the atmosphere’s energy budget. Changes in global mean precipitation in climate model projections closely follow changes in clear-sky atmospheric radiative cooling, obeying an energetic constraint. Climate models vary in how heavy this rain is when it falls, but they generally agree on many aspects of how this distribution changes with warming. The changes in the distribution of rain can be described by “shift” and “increase” modes of change of the distribution. One aspect of precipitation change that models disagree about is the rate of change of extreme precipitation change with warming. These changes in extreme precipitation do not depend on the type of forcing that drives the warming (in contrast to mean precipitation). Convective organization could in principle contribute to the disagreement across models, and some methods of quantifying this relationship are in development.

Friday, May 6, 2016
12:00-1:00 pm
Mesa Lab, Damon Room
(Bring your lunch)