Comparison of SMILES ClO profiles with satellite, balloon-borne and ground-based measurements

[摘要] We evaluate the quality of ClO profiles derived from theSuperconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on theInternational Space Station (ISS). Version 2.1.5 of the level-2 productgenerated by the National Institute of Information and CommunicationsTechnology (NICT) is the subject of this study. Based on sensitivity studies,the systematic error was estimated as 5–10 pptv at the pressurerange of 80–20 hPa, 35 pptv at the ClO peak altitude(~ 4 hPa), and 5–10 pptv atpressures ≤ 0.5 hPa for daytime mid-latitude conditions. Fornighttime measurements, a systematic error of 8 pptv was estimatedfor the ClO peak altitude (~ 2 hPa). The SMILES NICTv2.1.5 ClO profiles agree with those derived from another level-2processor developed by the Japan Aerospace Exploration Agency (JAXA) withinthe bias uncertainties, except for the nighttime measurements in the low andmiddle latitude regions where the SMILES NICT v2.1.5 profiles have a negativebias of ~ 30 pptv in the lower stratosphere. This bias isconsidered to be due to the use of a limited spectral bandwidth in theretrieval process of SMILES NICT v2.1.5, which makes it difficult todistinguish between the weak ClO signal and wing contributions of spectralfeatures outside the bandwidth. In the middle and upper stratosphere outsidethe polar regions, no significant systematic bias was found for the SMILESNICT ClO profile with respect to data sets from other instruments suchas the Aura Microwave Limb Sounder (MLS), the Odin Sub-Millimetre Radiometer(SMR), the Envisat Michelson Interferometer for Passive Atmospheric Sounding(MIPAS), and the ground-based radiometer at Mauna Kea, which demonstrates thescientific usability of the SMILES ClO data including the diurnalvariations. Inside the chlorine-activated polar vortex, the SMILES NICT v2.1.5ClO profiles show larger volume mixing ratios by 0.4 ppbv(30%) at 50 hPa compared to those of the JAXA processedprofiles. This discrepancy is also considered to be an effect of the limitedspectral bandwidth in the retrieval processing. We also compared the SMILESNICT ClO profiles of chlorine-activated polar vortex conditions withthose measured by the balloon-borne instruments: Terahertz and submillimeterLimb Sounder (TELIS) and the MIPAS-balloon instrument (MIPAS-B). Inconclusion, the SMILES NICT v2.1.5 ClO data can be used atpressures ≤ ~30 hPa for scientific analysis.

[学科分类] 几何与拓扑