Orographic disturbances in the upper atmosphere

• Published in: Journal of atmospheric and solar-terrestrial physics Vol. 90-91; pp. 124 - 131
• Main Authors: Semenov, Anatoly I., Shefov, Nikolay N., Medvedeva, Irina V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2012
• Subjects: Altitude; Atmospherics; Disturbances; Gravity wave energy; Mesopause; Mountains; Obstacles; Orographic disturbances; Ridges; Upper atmosphere; Mesopause; Gravity wave energy; Orographic disturbances
• ISSN: 1364-6826; 1879-1824
• DOI: 10.1016/j.jastp.2012.05.009

Interaction of atmospheric non-stationary stream with obstacles on the Earth's terrestrial surface causes disturbances which are a source of various wave processes. A study of such processes and their influence on the upper atmosphere temperature regime was carried out at Kislovodsk high-mountainous scientific station of the Institute of Atmospheric Physics Russian Academy of Sciences (IAP RAS) by measuring the mesopause temperature in the northern leeward area of the Caucasian ridge. Using the data of the spectrophotometric measurements of the upper atmosphere hydroxyl emission characteristics over almost two decades, information about the orographic disturbances at the mesopause altitudes were obtained and features of their generation in the surface atmosphere were studied. It was found that the atmospheric temperature at altitudes around 90km in the lee of mountains increased by 10K (the mean value is about 200K) at a distance of about 150km from the ridge. The 300-km width of the observed airglow disturbances is from the observations near the Ural and Caucasian mountains. The sources of wave disturbances are shown to be concentrated near the mountainous irregularities of the Caucasian ridge. These sources appear in the troposphere at altitudes of about 4km. The process of generating waves with periods from 7 to 20min were believed to be caused by wind gusts. The spatial distribution of energy flow in the lee of the mountains was calculated and amounts to about 3ergcm−2s−1. ► Interaction of air stream with obstacles on Earth surface produces wave processes. ► The process of generating waves with periods 7–20min is caused by wind gusts. ► Energy flow in the lee of the mountains was calculated. ► The value of this flow is about 3ergcm−2s−1.