TIMED/SABER Observations Of Lower Mesospheric Inversion Layers And Atmospheric Tides

Using10-yr TIMED/SABER (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) Level2A temperature data, we investigate the thermal structure and tidal waves in middle and upper atmosphere. This dissertation is consisted of the following parts:(1) study of lower mesospheric inversion layers (lower-MILs);(2) study of diurnal and semi-diurnal migrating tides;(3) study of diurnal and semi-diurnal non-migrating tides.In chapter2, we statistically analyze the parameters (occurrence rate amplitude, thickness, bottom and top temperature etc.) of lower-MILs and find that the seasonal variation of lower-MILs is latitudinal dependent. At low-latitude, lower-MILs present semi-annual variability with the amplitude maximum and minimum around equinoxes and solstices, respectively. Basing on the characteristics of lower MILs, we further investigate its possible formation mechanisms. It is found that the joint contribution of semi-annual oscillation (SAO) in background temperature and the transient structure of temperature diurnal migrating tide is the primary cause of low-latitude lower-MILs. Moreover, by analyzing the longitudinal structure of lower-MILs, we suggest that the transient structure of composite wave of stationary planetary wave and westward propagation16-day wave with zonal wave number unity is a significant cause of large-scale MILs during middle latitude winter.In chapter3, diurnal and semi-diurnal migrating tides (DW1and SW2) are studied in detail on latitudinal and altitude variations and seasonal and inter-annual variations. Some typical observational results are presented as follows:(1) Both DW1and SW2exhibit different latitudinal distribution features at different altitudes. For example, DW1is stronger at middle latitude in the stratosphere and low thermosphere while its amplitude peaks in the mesosphere in the tropical region.(2) DW1exhibits two-peak vertical structure in the low-latitude mesosphere.(3) Tropical DW1and low thermosphere SW2are characterized by semi-annual variation.(5) Comparison of SABER observing and GSWM SW2indicates significant differences.In chapter4, we present the SABER observational results of diurnal and semi-diurnal non-migrating tides.10-yr climatology averaged zonal wave number spectrum suggests8primary non-migrating components:DE3, DO, DW2, SE2, SE5, SW1, SW3and SW6. Analyzing the least square fitted amplitudes, we find that DE3and SW3are the most prominent diurnal and semidiurnal non-migrating tides with maximum around16and11K, respectively. DE3is predominent over tropical region while DO and DW2are stronger in middle latitude. The semi-diurnal non-migrating tide becomes complex in MLT where SE5and SW6occur with SE2, SW1and SW3.