Speaker: Marianna Linz
Title: Age of Air and the Circulation of the Stratosphere
The circulation of the stratosphere determines spatial distributions of trace gases, which impact climate, radiation and human health. The circulation has been predicted to strengthen with climate change, but observations are ambiguous. While observations have provided an excellent qualitative picture of the circulation, quantifying the stratospheric circulation has been unclear, and so trend calculations from most observations are inconclusive. The idealized tracer “age” of stratospheric air describes how long an air parcel has been in the stratosphere, and I have developed theory to quantify the stratospheric circulation by utilizing the unique properties of age. I will show validation of this theory with an idealized model and a comprehensive GCM. I will then show how “age” is derived from nitrous oxide and sulfur hexafluoride measurements from satellites in order to apply the theory. This is the first calculation of the mean global overturning strength of the stratosphere from observations. I will conclude with a brief look at extensions of the theory both within the stratosphere and beyond. Finally, I will share some innovative new measurements and planning for an observational campaign that would enable the calculation of the critical stratospheric circulation trends that have been so elusive to date.