Open AccessStratospheric N 2 O 5 in the austral spring 2002 as retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)
Author(s) -
Mengistu Tsidu G.,
von Clarmann T.,
Stiller G. P.,
Höpfner M.,
Fischer H.,
Glatthor N.,
Grabowski U.,
Kellmann S.,
Kiefer M.,
Linden A.,
Milz M.,
Steck T.,
Wang D. Y.,
Funke B.
Publication year - 2004
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jd004856
Subject(s) - atmospheric sounding , polar vortex , air mass (solar energy) , atmospheric sciences , depth sounding , stratosphere , mixing ratio , michelson interferometer , spectral line , atmospheric chemistry , physics , altitude (triangle) , emission spectrum , latitude , environmental science , astrophysics , geology , meteorology , interferometry , ozone , astronomy , geometry , oceanography , boundary layer , thermodynamics , mathematics
N 2 O 5 was retrieved from infrared limb emission spectral radiances made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the European environmental satellite (ENVISAT). The measurements were taken during the period covering the Antarctic polar vortex split between 20 September and 13 October 2002. The retrieval of N 2 O 5 is aggravated by its continuum‐like emission feature covering a wide spectral region, which is hardly distinguishable from background continuum emission. The method of constraining the background continuum in the N 2 O 5 analysis spectral region to its value in a N 2 O 5 ‐free spectral region was found to be appropriate to solve this problem. Retrieved volume mixing ratios (VMR) of N 2 O 5 exhibit features consistent with the dynamics prevalent at the time in the Antarctic and known N 2 O 5 chemistry governing diurnal variability. The observations of low N 2 O 5 inside vortex air mass and rich N 2 O 5 exvortex air mass are strongly in support of the chemistry that governs its partitioning within the NO y family. The enhanced nighttime high geographic latitude N 2 O 5 VMR with a peak of 4.4 ppbv in the altitude range of 32–37 km during the last week of September 2002 is consistent with air mass transport from lower to high latitudes and temperature‐sensitive N 2 O 5 formation chemistry. N 2 O 5 enhancement up to 6 ppbv was also observed by the Cryogenic Limb Array Etalon Spectrometer(CLAES) and Improved Stratospheric and Mesospheric Sounder (ISAMS) experiments on Upper Atmospheric Research Satellite (UARS) during Northern Hemisphere January 1992 stratospheric warming which was a factor of 3 larger than any measurements of N 2 O 5 prior to UARS. In contrast, a maximum of 4.4 ppbv N 2 O 5 VMR observed by MIPAS at 32–37 km is only a factor of 2 larger than its prewarming values.