| A method to explicitly estimate the short term variability of the migrating diurnal tide on a global scale is presented and analyzed. The method employs temperature data from two satellite instruments: the MLS (Microwave Limb Sounder) instrument on the EOS (Earth Observing System) Aura spacecraft and the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on the TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) spacecraft. By taking advantage of the four daily solar local time measurements inherent from the two instruments, a least squares fit representing the migrating diurnal tide is constructed. Consequently, the daily zonal mean, migrating diurnal amplitude and migrating diurnal phase are all estimated on a daily basis.;The main objective of the study is to analyze the feasibility of this estimation method. A comparative analysis was first conducted that reveals biases between the two instrument data sets that are as large as 10 K. These instrument biases are removed to reduce potential error. Other error sources include the presence of other tides and waves. The effects of non-migrating tides and waves are attenuated by zonal averaging at constant solar local times. Effects of migrating tides are not attenuated by zonal averaging. The effect of the migrating semidiurnal tide, in particular, is significantly reduced by the least squares approach if the solar local time is evenly sampled. The sampling of solar local time, which changes over time due to orbit of the TIMED satellite, displays a large influence on the results as poor sampling causes nearly linearly-dependent solutions.;The quality of the results for the diurnal amplitude and phase varies over time and geographic location. Comparisons to theory and past observation indicate that estimates are sufficient for scientific analysis near the equatorial-mesosphere where the solar local time sampling is well-spaced, the amplitude of the migrating diurnal tide is large, and the amplitudes of other tides and waves are small. A wavelet analysis for the equatorial mesosphere is performed to illustrate both the long term and short term variations of the tide. |
