| The middle and upper atmosphere is the least cognitive region,including the stratosphere,the mesosphere,and the thermosphere.With accumulation of the observational data and the development of the near space vehicle,analysis and simulation of middle and upper atmosphere become hot spots.Due to the limits of foregoing data and methods,former researches only gave rough descriptions of some phenomena.In addition,the detection data of the middle and upper atmosphere in China are deficient and some detection technologies significantly lag behind abroad.It is of great scientific importance to analyze and apply those autonomous data to the researches of environment characteristics and to establish the middle and upper atmospheric empirical model in China.Based on TIMED/SABER temperature data,the FPI wind data in Kelan and the China's first successful falling-sphere experiment data,the data themselves and the environment of middle and upper atmosphere are analyzed.The main contents include the following aspects:(1)Basing on SABER 2.0 temperature data,we mainly study the properties of long-term variations and the mesospheric inversion layer.Because of a small Coriolis parameter in the equatorial region,a small difference in the temperature field could be magnified in the zonal wind field,leading to the asymmetric meridional structure of the zonal wind stratospheric SAO amplitude with respect to the equator.The phase inversion between 75 and 85 km may cause the 11-K enhancement in the background temperature on average,with stronger enhancement in spring equinox than in autumn equinox.The difference between two equinoxes can be explained by the seasonal asymmetries at 75 and 85 km.The TO is significant in the tropical regions.The spectral peak of TO is probably a sub-peak of the QBO and is due to modulation of the QBO.The 3-year periodicities in the SAO match well with the TO at 85 km at equator,indicating the potential interaction by the TO with SAO there.In addition,the ENSO signal may modulate the amplitude of the TO,mainly in the lower stratosphere.(2)Based on the wind data observed by FPI over Kelan,the characteristics of winds and planetary waves at altitudes of 87,97 and 250 km are investigated.Firstly,the midnight winds have been compared with those from HWM07 and TIDI.It is revealed that the improvement of HWM-07 model needs to further consider the influence of solar activity and interplanetary magnetic field.Secondly,the Lomb-Scargle analysis and the least squares harmonic fitting method have been used to derive amplitudes at the three altitudes.The results show the following: At 87 and 97 km,the 16-day waves are prominent at autumn,winter and spring during 2013–2014,while the 6.5-day waves tend to dominant the spring and autumn.Both of the two planetary waves have weak amplitudes around mesopause.The amplitudes are stronger in meridional wind than zonal at 250 km,three typical planetary wave period bands of meridional wind show that the strongest amplitudes persist from May to October.(3)Basing on the China's first falling-sphere experiment in Korla,we calculated the wind data by inputting the NRLMSISE-00 model density.The results show that inaccuracies in the NRLMSISE-00 density have hardly any influence on the calculated winds,while the uncertainties in vertical acceleration of the sphere can make large contribution to the wind errors at high altitudes.The second Modern-Era Retrospective Analysis for Research and Applications(MERRA-2)data match well with the experimentally determined zonal wind,with a correlation coefficient of 0.98.However,the experimentally determined meridional wind is much less consistent with the MERRA-2 data.This may be due to the fact that the reanalysis data cannot capture the full features of the meridional wind.The main wavelengths of gravity wave are concentrated at 8.5 km,5 km and 3.5 km at the range of 30~60 km. |
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