Subtropical trace gas profiles determined by ground-based FTIR spectroscopy at Izaña (28° N, 16° W): Five-year record, error analysis, and comparison with 3-D CTMs

[摘要] Within the framework of the NDSC (Network for the Detection ofStratospheric Change) ground-based FTIR solar absorption spectrahave been routinely recorded at Izaña Observatory(28° N,16° W) on Tenerife Island since March1999. By analyzing the shape of the absorption lines, and theirdifferent temperature sensitivities, the vertical distribution ofthe absorbers can be retrieved. Unique time series of subtropicalprofiles of O₃, HCl, HF, N₂O, and CH₄ are presented. Theeffects of both dynamical and chemical annually varying trace gascycles can be seen in the retrieved profiles. These includeenhanced upwelling and photochemistry in summer and a moredisturbed atmosphere in winter, which are typical of thesubtropical stratosphere. A detailed error analysis has beenperformed for each profile. The output from two differentthree-dimensional (3-D) chemical transport models (CTMs), whichare forced by ECMWF analyses, are compared to the measuredprofiles. Both models agree well with the measurements in trackingabrupt variations in the atmospheric structure, e.g. due totropical streamers, in particular for the lower stratosphere.Simulated and measured profiles also reflect similar dynamical andchemical annual cycles. However, the differences between theirmixing ratios clearly exceed the error bars estimated for themeasured profiles. Possible reasons for this are discussed.

[学科分类] 大气科学