SLS - Catherine Wilka (MIT)
Title: Ozone Chemistry in the Lower Stratosphere: Drivers, Trends, and Impacts
Stratospheric ozone is both vital to the health of the biosphere and a major influence on the middle atmosphere's temperature structure and circulation. While the fundamentals of ozone chemistry have been well understood for decades, recent advances in modeling and longer observation records provide valuable opportunities for us to deepen our understanding of the complexities of these processes in space and time. The first part of this talk will examine how moderate and large volcanic eruptions influence ozone trends by increasing the available surface area for chemical reactions in the lower stratosphere. Our results show that the natural variability of volcanic activity has modified the timing of anthropogenic-driven ozone changes in significant ways, deepening the depletion in the 1990s and slowing the recovery in the early 2010s. The second part of this talk will focus on the unusually cold Arctic Spring of 2020, which resulted in record ozone depletion, in the context of a hypothetical "World Avoided" scenario wherein the Montreal Protocol was never passed and ozone depleting substances continued to rise. Under this scenario, an Arctic ozone hole rivaling current Antarctic ones would have appeared, with potentially serious consequences for people and the biosphere. The final part of this talk will shift focus to the tropics, where we use modeling studies to link tropospheric tropical dynamics to stratospheric chemistry and show that chlorine activation, a necessary precursor to ozone depletion, can occur in regions where it was previously thought to be absent.
About this Series
The Atmosphere, Ocean and Climate Sack Lunch Seminar Series is an informal seminar series within PAOC that focuses on more specialized topics than the PAOC Colloquium. Seminar topics include all research concerning the science of atmosphere, ocean and climate. The seminars usually take place on Wednesdays from 12-1pm in 54-915. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.