Mesosphere and lower thermosphere temperature anomalies during the 2002 Antarctic stratospheric warming event

摘要

We present kinetic temperatures at ~87 km and ~94 km altitudesinferred from OH (6,2) and O At(0,1) airglow observations, respectively,at South Pole (90° S), Antarctica in the austral winter of 2002.These OH and O rotational temperatures measurements show mesosphere andlower thermosphere (MLT) temperature anomalies prior to the 2002 SouthernHemisphere Sudden Stratospheric Warming (SSW) . In this paper we focus on thefirst of the three minor stratospheric warmings which preceded the major SSWevent. Temperature anomalies observed in the MLT region show sudden cooling(Δ=~30 K) in OH temperatures accompanied by warming (Δ=~15 K)in O temperatures preceding the onset of SSW event by aboutthree to four weeks. This shallow vertical extent of mesospheric cooling isin agreement with the numerical simulation of Coy et al. (2005),however, the model cooling was centered well below the mesopause level. Theother observed feature of the South Pole MLT temperature dataset is theintensification of planetary wave activity prior to the onset of SSW event.Fourier analyses of both OH and O temperatures show amplification ofplanetary wave activity in the 5–10 day range prior to the onset of SSW. Thetiming of wave amplification seen in the wave spectra coincides with the peakin OH and O temperature anomalies.