München 2019 – scientific programme
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UP: Fachverband Umweltphysik
UP 8: Physics of the middle atmosphere
UP 8.5: Talk
Thursday, March 21, 2019, 12:20–12:40, HS 22
Response of the middle atmospheric temperature to the solar 27-day cycle — •Piao Rong1,2 and Christian von Savigny1 — 1Institute of Physics, University of Greifswald, Greifswald, Germany — 2School of Science, Xi'an Jiaotong University, Xi'an, China
This contribution discusses the presence and characteristics of solar 27-day signatures in middle atmospheric temperature observed by the Microwave Limb Sounder (MLS) on NASA's Aura spacecraft. We use the superposed epoch analysis (SEA), the time-lagged linear regression method (sensitivity analysis), and a Monte-Carlo test method (significance test) to explore the dependence of the results on different parameters (e.g., smoothing filter, window width and epoch centers), on solar activity and season, as well as on latitude. Using different parameters does impact the results to a certain degree, but it does not affect the overall characteristics. The 27-day signature in temperature is stronger during winter than during summer. The sensitivity of temperature to solar 27-day forcing is larger at high latitudes than at low latitudes in strong solar activity years. However, in weak solar activity years, the sensitivity maximum appears at the equatorial mesopause. In addition, the sensitivity values of the strong solar activity years are smaller than the values in the weak solar activity years. That means, in weak solar activity years, the temperature may be affected by some factors other than the 27-day solar cycle to induce so high sensitivity.