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Denitrification in the Arctic mid‐winter 2004/2005 observed by airborne submillimeter radiometry
Author(s) -
Kleinböhl Armin,
Bremer Holger,
Küllmann Harry,
Kuttippurath Jayanarayanan,
Browell Edward V.,
Canty Timothy,
Salawitch Ross J.,
Toon Geoffrey C.,
Notholt Justus
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl023408
Subject(s) - altitude (triangle) , atmospheric sciences , polar vortex , environmental science , radiometer , arctic , stratosphere , the arctic , polar , climatology , oceanography , geology , physics , remote sensing , geometry , mathematics , astronomy
We present measurements of unusually low mixing ratios of HNO 3 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 HNO 3 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 HNO 3 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.