Denitrification in the Arctic mid-winter 2004/2005 observed by airborne submillimeter radiometry

We present measurements of unusually low mixing ratios of HNO3 in the exceptionally cold Arctic vortex of late‐January and early‐February 2005. The measurements were obtained by the airborne submillimeter radiometer ASUR during the polar aura validation experiment (PAVE). The distribution of HNO3 in...

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Bibliographic Details
Published in:Geophysical research letters 2005-10, Vol.32 (19), p.L19811.1-n/a
Main Authors: Kleinböhl, Armin, Bremer, Holger, Küllmann, Harry, Kuttippurath, Jayanarayanan, Browell, Edward V., Canty, Timothy, Salawitch, Ross J., Toon, Geoffrey C., Notholt, Justus
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
Exact sciences and technology
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Summary:We present measurements of unusually low mixing ratios of HNO3 in the exceptionally cold Arctic vortex of late‐January and early‐February 2005. The measurements were obtained by the airborne submillimeter radiometer ASUR during the polar aura validation experiment (PAVE). The distribution of HNO3 inside the vortex reaches minima below 4 ppbv around 22 km altitude and maxima above 13 ppbv around 16 km altitude, with a considerable spatial variability. We estimate a vortex averaged denitrification of 3.1 ± 0.8 ppbv around 20 km altitude, and slight renitrification below ∼15.5 km altitude. The observed HNO3 deficit is largest (∼6 ppbv) near the center of the vortex, where the air masses had experienced temperatures below the NAT formation threshold for 80–100% of the previous 20 days according to back trajectories. This suggests that the main denitrification mechanism is based on sedimenting nitric acid trihydrate particles.
ISSN:0094-8276
1944-8007
DOI:10.1029/2005GL023408