A weak (minor) stratospheric warming event and transition of the stratosphere to the background thermal regime observed in 2011 is analyzed in comparison with the preceding (major) warming event observed from January 22 till January 29, 2010. During this period, the temperature in the stratopause at some nights increased up to +30°C, and the tropopause height decreased to 37-38 km. In February, the temperature noticeably decreased; its positive deviation from the average monthly value was observed in the altitude range below 40 km. The stratopause reached record low altitudes of 23-25 km. In April, the vertical temperature profile approached that, described by the CIRA-86 model. For the warming event in 2011, dynamic events occurred in January. Thus, a sharp temperature change was observed on January 14, when in accordance with lidar and satellite data, the stratopause height decreased to 32-35 km, and the temperature deviation reached 42-45°K. On January 15, from the data of lidar measurements, the stratopause height was smeared (it extended from 30 to 37 km), and from the data of satellite observations, it decreased by 31 km. In the subsequent months in February-April, the vertical temperature profile was stabilized with transition to the background state.
stratosphere, vertical temperature profile, winter stratospheric warming events, lidar observations