Based on a recently developed all-sky forward model (σ-IASI/F2N) for the computation of spectral radiances in the range 100 to 2760 cm-1, the paper addresses the spring onset of the Antarctica ozone hole with infrared observations from the IASI (Infrared Atmospheric Sounder Interferometer) satellite sounder. The Antarctica ozone hole is a cyclic event that grows in normal conditions in late August and collapses in late November/early December. Because of climate change (cooling of the stratosphere), the O3 hole is expected to become deeper. Indeed, 2021 and 2023 have been characterized by very spatially extensive and deep ozone hole. To demonstrate that we can gain further insights into these phenomena with the help of infrared nadir viewing observations, we have developed an all-sky retrieval tool, which inverts the whole IASI infrared spectrum to simultaneously estimate thermodynamic and geophysical parameters, including ozone and nitric acid, which are key parameters in analyzing the Antarctic ozone hole. Infrared sounders acquire data day and night, unlike visible and ultraviolet sounders, which are only operational during daytime. This enables us to acquire data also during the polar night, which is 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), showing 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. For 2023, our findings also show that O3 depletion episodes began as early as July. Although demonstrative, our analysis evidences the importance of Numerical Weather Prediction centers to assimilating all-sky infrared radiances (day, night, clear, or with ice or water clouds) to get insights into providing a more comprehensive picture of the Southern Spring ozone depletion over Antarctica.

中文翻译：

---

全天空、昼夜 IASI 观测的物理反演方案的演示及其在南极洲臭氧空洞开始分析中的应用：反演评估和正演建模的一致性


基于最近开发的用于计算 100 至 2760 cm-1 范围内的光谱辐射度的全天空前向模型 （σ-IASI/F2N），该论文通过 IASI（红外大气测深仪干涉仪）卫星测深仪的红外观测解决了南极洲臭氧空洞的春季开始。南极洲臭氧空洞是一个周期性事件，在 8 月下旬在正常条件下增长，并在 11 月底/12 月初崩溃。由于气候变化（平流层冷却），预计 O3 空洞会变得更深。事实上，2021 年和 2023 年的特点是空间非常广泛和深的臭氧空洞。为了证明我们可以在红外最低点观测观测的帮助下进一步了解这些现象，我们开发了一种全天空检索工具，该工具可以反转整个 IASI 红外光谱，以同时估计热力学和地球物理参数，包括臭氧和硝酸，这是分析南极臭氧空洞的关键参数。红外测深仪昼夜采集数据，这与可见光和紫外线测深仪不同，它们仅在白天运行。这使我们能够在极夜采集数据，这是 O3 空穴形成的关键时期。冰极平流层云已被识别并拟合到我们的方案中。已经检索了 2021 年 7 月、9 月和 2023 年 7 月、9 月和 10 月的大气臭氧图，以及硝酸、温度和平流层高度的地图。将结果与 TROPOMI（对流层监测仪器）和 OMI（臭氧监测仪器）的结果进行比较，显示出非常好的一致性。 同时提取的 O3 和 HNO3 的比较表明，臭氧空洞的出现与南极洲平流层的相关反硝化作用有关。对于 2023 年，我们的研究结果还显示，O3 耗竭事件早在 7 月就开始了。虽然是示范性的，但我们的分析证明了数值天气预报中心对于同化全天红外辐射（白天、黑夜、晴朗或有冰云或水云）的重要性，以深入了解提供更全面的南极洲南春季臭氧消耗情况。