There is strong correlation among the ionospheric longitudinal structures of wavenumber-3(WN3),wavenumber-4(WN4),and eastward-propagating diurnal tides with zonal wave numbers s = 2 and 3(DE2 and DE3) in the upper atm...There is strong correlation among the ionospheric longitudinal structures of wavenumber-3(WN3),wavenumber-4(WN4),and eastward-propagating diurnal tides with zonal wave numbers s = 2 and 3(DE2 and DE3) in the upper atmosphere.The total electron content derived from the Global Ionospheric Maps of the Jet Propulsion Laboratory is used to deduce the latitudinally total electron content(ITEC) in the low-latitude ionosphere,and TIDE/TIMED observations are employed to obtain zonal and meridian winds of the mesopause and lower thermosphere.Through Fourier transformation,various ionospheric longitudinal harmonic components and tidal patterns are derived from the ionospheric and upper-atmospheric observations,and we compare the annual/inter-annual variations in ionospheric harmonic components WN3 and WN4 with those in atmospheric tides(DE2 and DE3).It is found that the annual and inter-annual variations in WN3 and WN4 are consistent with those in DE2 and DE3 zonal wind components respectively,while they are inconsistent with those in the meridian components.We then decompose the harmonic components into "tidal patterns",finding that the "DE2" and "DE3" patterns are the main parts of WN3 and WN4 respectively.Their annual and inter-annual variations are similar to those of atmospheric tidal patterns(DE2 and DE3).Complex correlation results show that correlation between the ionospheric "DE2" in WN3 and the atmospheric tidal DE2 zonal wind component is quite strong in the Northern Hemisphere,while that between the ionospheric "DE3" in WN4 and the atmospheric tidal DE3 zonal wind component is much stronger at low latitudes.At the same time,the contribution of the meridian wind component is very weak.Above all,the atmospheric tidal DE2 and DE3 patterns are important factors of the ionospheric WN3 and WN4 structures.展开更多
The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. Fr...The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH （6-2） and 02 （0-1） airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.展开更多
基金supported by the KIP Pilot of the Chinese Academy of Sciences (KZCX2-YW-123)the National Natural Science Foundation of China (40974090 and 40636032)the National Basic Research of China (2006CB806306)
文摘There is strong correlation among the ionospheric longitudinal structures of wavenumber-3(WN3),wavenumber-4(WN4),and eastward-propagating diurnal tides with zonal wave numbers s = 2 and 3(DE2 and DE3) in the upper atmosphere.The total electron content derived from the Global Ionospheric Maps of the Jet Propulsion Laboratory is used to deduce the latitudinally total electron content(ITEC) in the low-latitude ionosphere,and TIDE/TIMED observations are employed to obtain zonal and meridian winds of the mesopause and lower thermosphere.Through Fourier transformation,various ionospheric longitudinal harmonic components and tidal patterns are derived from the ionospheric and upper-atmospheric observations,and we compare the annual/inter-annual variations in ionospheric harmonic components WN3 and WN4 with those in atmospheric tides(DE2 and DE3).It is found that the annual and inter-annual variations in WN3 and WN4 are consistent with those in DE2 and DE3 zonal wind components respectively,while they are inconsistent with those in the meridian components.We then decompose the harmonic components into "tidal patterns",finding that the "DE2" and "DE3" patterns are the main parts of WN3 and WN4 respectively.Their annual and inter-annual variations are similar to those of atmospheric tidal patterns(DE2 and DE3).Complex correlation results show that correlation between the ionospheric "DE2" in WN3 and the atmospheric tidal DE2 zonal wind component is quite strong in the Northern Hemisphere,while that between the ionospheric "DE3" in WN4 and the atmospheric tidal DE3 zonal wind component is much stronger at low latitudes.At the same time,the contribution of the meridian wind component is very weak.Above all,the atmospheric tidal DE2 and DE3 patterns are important factors of the ionospheric WN3 and WN4 structures.
基金supported by the National Natural Science Foundation of China (Grant No. 40974086)the National Important Basic Research Project (Grant No. 2011CB811405)
文摘The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH （6-2） and 02 （0-1） airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.
