Observations Of Atmospheric Mesopause And Wave Turbopause By SABER/TIMED Satellite

Temperature is a very important parameter in atmospheric science. It varies in different altitudes. People divide atmosphere into different layers by temperature vriations. The temperature decreases sharply in mesosphere while it increases quickly in lower thermosphere. The mesopause is the coldest place in the atmosphere. All these phenomenen shows that, the temperature in the middle and upper atmosphere is relative with the physical and chemical process in atmosphere. Temperature is also relative with atmospheric turbulence and turbopause.We study on mesopause, wave turbopause and wave dissipations quantatively in middle and upper atmosphere by global and long time data on SABER observatory TIMED satellite, NASA.We discuss the temperature and height of mesopause in detail by satellite data. The observation as long as8years indicates that, the mesopause is stable in low latitude and equator all the year. The mesopause in high latitude is annual oscillation with an obvious durative two-level mesopause. The summer lower secondary mesopause is lower than winter mesopause12～16km usually. The two-level mesopause lasts different time in different latitdes. Generally speaking, the secondary mesopause starts from about30°N, and lasts for about3month in40°N and more than4month in50°N. In the southern hemisphere, the secondary mesopause lasts3month in50°S while only a few days in40°S. The starting latitude of two-level mesopause in northern hemisphere is middle latitude while in southern hemisphere is mid-high latitude. There exists an asymmetry of mesopause temperature and height, however, the assymetry mostly consists in middle latitude, which seems disappeared in low and high latitudes.We also analysis the variations of atmospheric wave turbopause by studying on atmospheric wave activity presented by temperature variances. The wave turbopause reveals evidently latitudinal and seasonal variations. The wave turbopuse in middle and high latitude during winter is about110～115km while95km during summer. The winter wave turbopause is clearly higher than summer in middle and high latitude. The variation range of wave turbopause in mid-low latitude and equtor is smaller. The wave turbopause varies between90～100km nearly. A clear annual oscillation is found in mid-high latitude and weak semiannual oscillation in low latitude. The variation of wave trbopause could be relative with background temperature, atmospheric stratification and atmospheric wave activity. Like mesopause, the asymmetry in wave turbopause is obvious too. Mid-high and high latitude are main area where most asymmetry of wave turbopause appears.Besides, we calculate the wave activity growth scale height in different altitude by piecewise exponential fitting the temperature variance. And we compare it with atmospheric density scale height. The results indicate that, wave activity growth scale height is obviously greater than atmospheric density scale height below about110km. It shows great dissipations below low thermosphere. Wave activity growth scale height is nearly equal to atmospheric density scale height, which implies that atmospheric dissipation get weak and disappeared. The energy of wave is approximately conservative while propagating. The atmospheric wave growth scale height varies seasonally in mid-high latitude. The wave growth scale height is greater in winter and smaller in summer.