Validation of MIPAS ClONO2 measurements

• Main Authors: Hopfner, M, von Clarmann, T, Jones, Nicholas B, Griffith, David W, Toon, G C, Mahieu, E, Zander, R, Wood, S, Blumenstock, T, Hannigan, J, Coffey, M, Hase, F, Fischer, H W, Mellqvist, J, Strandberg, A, Warneke, Thorsten, Blom, C E, Piesch, C, Jucks, K W, Chance, K, Kouker, W, Reddmann, T, Boone, C, Oelhaf, H, Keim, C, Glatthor, N, Kiefer, M, Kellmann, S, Ruhnke, R, Linden, A, Liu, G Y, Funke, B, Milz, M, Schneider, M, Wetzel, G, Steck, T, Kleinert, A, Mikuteit, S, Stiller, G P, Grabowski, U, Walker, K A, Bernath, P, Friedl-Vallon, F, Notholt, Justus
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Research Online 2007
• Subjects: Validation; MIPAS; ClONO2; measurements; GeoQUEST; Life Sciences; Physical Sciences and Mathematics; Social and Behavioral Sciences; Kiruna; Spitsbergen
• Online Access: https://ro.uow.edu.au/scipapers/3692; https://ro.uow.edu.au/cgi/viewcontent.cgi?article=7034&context=scipapers

Altitude profiles of ClONO2 retrieved with the IMK (Institut fur Meteorologie und Klimaforschung) science-oriented data processor from MIPAS/Envisat (Michelson Interferometer for Passive Atmospheric Sounding on Envisat) mid-infrared limb emission measurements between July 2002 and March 2004 have been validated by comparison with balloon-borne (Mark IV, FIRS2, MIPASB), airborne (MIPAS-STR), ground-based (Spitsbergen, Thule, Kiruna, Harestua, Jungfraujoch, Izana, Wollongong, Lauder), and spaceborne (ACE-FTS) observations. With few exceptions we found very good agreement between these instruments and MIPAS with no evidence for any bias in most cases and altitude regions. For balloon-borne measurements typical absolute mean differences are below 0.05 ppbv over the whole altitude range from 10 to 39 km. In case of ACE-FTS observations mean differences are below 0.03 ppbv for observations below 26 km. Above this altitude the comparison with ACE-FTS is affected by the photochemically induced diurnal variation of ClONO2. Correction for this by use of a chemical transport model led to an overcompensation of the photochemical effect by up to 0.1 ppbv at altitudes of 30–35 km in case of MIPAS-ACEFTS comparisons while for the balloon-borne observations no such inconsistency has been detected. The comparison of MIPAS derived total column amounts with ground-based observations revealed no significant bias in the MIPAS data. Mean differences between MIPAS and FTIR column abundances are 0.11±0.12×10^14 cm^−2 (1.0±1.1%) and −0.09±0.19×10^14 cm^−2 (−0.8±1.7%), depending on the coincidence criterion applied. Χ^2 tests have been performed to assess the combined precision estimates of MIPAS and the related instruments. When no exact coincidences were available as in case of MIPAS – FTIR or MIPAS – ACE-FTS comparisons it has been necessary to take into consideration a coincidence error term to account for χ^2 deviations. From the resulting χ2 profiles there is no evidence for a systematic over/underestimation of the MIPAS random error analysis.