Temperature disturbances in the subauroral lower thermosphere during winter stratospheric warming |
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| Authors: | V M Ignat’ev S V Nikolashkin |
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| Institution: | (1) Shafer Institute of Cosmophysical Research and Aeronomy, Siberian Division, Russian Academy of Sciences, pr. Lenina 31, Yakutsk, 677077, Russia |
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| Abstract: | Irregular variations in the temperature of the subauroral lower thermosphere during the winter stratospheric warming, which began in the first decade of December 2001 and continued to the end of the observational season (February 19, 2002), have been analyzed. The temperature measurements were based on the thermal broadening of the 557.7 nm oxygen emission measured during moonless nights at Maimaga optical station in the vicinity of Yakutsk (?=63°N, λ=129.7° E) using the Fabry-Pérot spectrometer. Isolated fragments of the map of contour lines of the horizontal temperature field and the globally averaged height-time section of the temperature at the levels of the 1, 2, 5, 10, 30, 50, and 70 hPa isobaric surfaces, obtained by the NOAA Meteorological Satellite Systems, as well as the F 10.7 and Ap indices have been used to analyze the cause-effect relation between the variations in the temperature of the subauroral lower thermosphere and winter stratospheric warming events. It is shown that, when warming is detected at heights of the lower thermosphere, the temperature can become higher than its model values by up to 20 K, which indicates that the planetary waves can penetrate to heights of the lower thermosphere and then propagate downward. In this case the atmosphere cools at heights of the lower thermosphere and tends to heat up above 10 hPa and to cool below 30 and 50 hPa; i.e., we observe the well-known fact of vertical alternation of cold and warm atmospheric regions detected during winter stratospheric warming events. |
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