Work

Demonstration of a physical inversion scheme for all-sky, day-night IASI observations and application to the analysis of the onset of the Antarctica ozone hole: Assessment of retrievals and consistency of forward modeling

Year: 2024

Type: article

Abstract: Based on a recently developed all-sky forward model (σ-IASI/F2N) for the computation of spectral radiances from the far to near-infrared part of the spectrum (100 to 2760 cm-1), the paper addresses the spring onset of the Antarctica ozone hole with high spectral resolution infrared observations from satellite, such as those measured by IASI (Infrared Atmospheric Sounder Interferometer). The Antarctica ozone hole is a cyclic event that grows in normal conditions in late August and collapses in late November, the beginning of December. Because of climate change (cooling of the stratosphere), the O3 hole is expected to become deeper with a depleted O3 mixing ratio, and, indeed, 2021 and 2023 have been two years with the most spatially extensive, and deep ozone hole. To demonstrate that we can gain further insights into the phenomenon by investigating with the help of infrared nadir viewing observations, we have developed an all-sky retrieval tool, which simultaneously inverts the full IASI infrared spectrum to retrieve thermodynamic and geophysical parameters, including ozone and nitric acid, which are key parameters in analyzing the Antarctic ozone hole. Unlike visible and ultraviolet sensors, we work on IASI day and night soundings, providing results all over the inner part of Antarctica in the polar night at a critical time for O3 hole formation. Ice polar stratospheric clouds have been identified and fitted with our scheme. Maps of atmospheric ozone, complemented with those of nitric acid, temperature, and lower stratosphere height, have been retrieved for July, September, and October 2021 and 2023. Results are compared to those derived from TROPOMI (TROPOspheric Monitoring Instrument) and OMI (Ozone Monitoring Instrument), which show a very good agreement. The comparison of simultaneously retrieved O3 and HNO3 shows that the onset of the ozone hole is associated with relevant denitrification in the Antarctica Stratosphere.

Source: Journal of Quantitative Spectroscopy and Radiative Transfer

DOI: 10.1016/j.jqsrt.2024.109211