Tracer Interrelationships, Stratospheric Age of Air, and the Strength of the Stratospheric Circulation and Mixing

Climate modeling studies have predicted an acceleration of Brewer Dobson Circulation (BDC) strength, which has impacts on global atmospheric radiation, climate, and composition. However, this acceleration has not been confirmed with observations. Models also disagree about the mean stratospheric circulation and mixing strength. The circulation and mixing determine the shapes of the relationships of long-lived stratospheric tracers, and so these relationships can be used as a metric to understand the BDC. The idealized age of air (AoA) tracer is also frequently used as a metric of the circulation strength, but AoA cannot be directly observed. We analyze tracer interrelationships of N₂O and AoA from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) from 2004-2021 and compare to previous relationships based on in situ observations. We use AoA:N₂O relationships to create a new AoA product based on N₂O data from the Microwave Limb Sounder (MLS). This work seeks to address whether observed BDC strength and its changes are comparable to models using the relationship between AoA and N₂O.