Speaker
Description
An important component of the reactive nitrogen (NO$_X$) budget of the stratosphere is nitrogen dioxide (NO$_2$), which participates in key reactions influencing the life cycle of stratospheric ozone. For example, it can limit the availability of reactive chlorine by forming chlorine nitrate (ClONO$_2$), but is also directly involved in catalytic cycles destroying ozone. A major source of stratospheric NO$_2$ is photolysis and oxidation of nitrous oxide (N$_2$O), which has been shown to have a decreasing lifetime [1], but increased tropospheric emission. Using the solar occultation technique, the Stratospheric Aerosol and Gas Experiment (SAGE) family of instruments have measured profiles of NO$_2$ concentration 1984-2005 (II), 2002-2005 (III/M3M) and 2017-present (III/ISS). Here these data sets are examined for a range of time scales: diurnal, seasonal, biennial, etc.; as well as following episodic increases in stratospheric aerosol amount from volcanic eruptions or extreme wildfire smoke. Comparisons are made with contemporaneous measurements by the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) and the Optical Spectrograph and Infrared Imaging System (OSIRIS). With the possible extension of the III/ISS record through this decade it is important to understand the linkage of the newest data product version (v6) to other NO$_2$ datasets.
[1] Prather, M. J., Froidevaux, L., and Livesey, N. J.: Observed changes in stratospheric circulation: decreasing lifetime of N$_2$O, 2005–2021, Atmos. Chem. Phys., 23, 843–849, https://doi.org/10.5194/acp-23-843-2023, 2023.
| Topic | Atmospheric composition (Earth and planets), chemistry and transport |
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