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Article Dans Une Revue Atmospheric Chemistry and Physics Discussions Année : 2024

Pyrogenic HONO seen from space: insights from global IASI observations

Résumé

Nitrous acid (HONO) is a key atmospheric component, acting as a major source of the hydroxyl radical (OH), the primary oxidant in the Earth's atmosphere. However, understanding its spatial and temporal variability remains a significant challenge. Recent TROPOMI/S5P UV-Vis measurements of fresh fire plumes shed light on the impact of global pyrogenic HONO emissions. Here, we leverage IASI/Metop's global infrared satellite measurements, complementing midday TROPOMI observations with morning and evening overpasses, to detect and retrieve pyrogenic HONO in 2007-2023. Employing a sensitive detection method, we identify HONO enhancements within concentrated fire plumes worldwide. Most detections are in the North Hemisphere mid and high latitudes, where intense wildfires and high injection heights favour HONO detection. IASI's nighttime measurements yield tenfold more HONO detections than daytime, emphasizing HONO's extended lifetime in the absence of photolysis during the night. The annual detection count increases by at least 3-4 times throughout the IASI time series, mirroring the recent surge in intense wildfires at these latitudes. Additionally, we employ a neural network-based algorithm for retrieving pyrogenic HONO total columns from IASI and compare them with TROPOMI in the same fire plumes. The results demonstrate TROPOMI's efficacy in capturing HONO enhancements in smaller fire plumes and in proximity to fire sources, while IASI's morning and evening overpasses enable HONO measurements further downwind, highlighting the survival of HONO or its secondary formation along long-range transport in smoke plumes.
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Dates et versions

insu-04341960 , version 1 (13-12-2023)

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Bruno Franco, Lieven Clarisse, Nicolas Theys, Juliette Hadji-Lazaro, Cathy Clerbaux, et al.. Pyrogenic HONO seen from space: insights from global IASI observations. Atmospheric Chemistry and Physics Discussions, 2024, ⟨10.5194/egusphere-2023-2707⟩. ⟨insu-04341960⟩
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