Mesospheric temperature trends derived from standard phase-height measurements

摘要

AbstractNew homogeneous time series of daily standard phase-height (SPH) and daily plasma scale-height (PSH) have been derived from a 50-year long-radio-wave measurement of the broadcasting station Allouis (France, 162kHz). The signal was received at Kühlungsborn (54°N, 12°E, Mecklenburg, Germany) and the present series is a third release. The daily time series of SPH shows in its spectrum dominant modes which are typical for the solar cycle (SC), for El Ni?o-Southern Oscillation (ENSO) and for quasi-biannual oscillation (QBO), indicating solar and lower atmospheric influences. Surprisingly, the time series of daily PSH shows a band of dominant cycles larger than 16 years.In order to exclude the influence of the winter anomaly in the determination of column-integrated mesospheric temperature trends the phase-height-temperature procedure is confined to summer months.The derived thickness temperature of the mesosphere decreased statistically significant over the period 1959–2008 after pre-whitening with summer mean of solar sun spot numbers. The trend value is in the order of about ?1.05K/decade if the stratopause trend is excluded. The linear regression is more pronounced, ?1.35K/decade for the period of 1963–1985 (2 SCs), but weaker, ?0.51K/decade during 1986-2008 (last 2 SCs). The linear regression is in very good agreement with a mean column-integrated mesospheric trend derived from OHP-Lidar temperatures on a monthly mean basis for the last two SCs.This clearly shows that the thickness temperature of the mesosphere