Technique to produce daily estimates of the migrating diurnal tide using TIMED/SABER and EOS Aura/MLS

Abstract

A technique to explicitly compute the day-to-day variability of the migrating diurnal tide (DW1) between 20km and 80km on a global scale is presented and analyzed. Our 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 from the two instruments, a least squares fit representing the DW1 is constructed. Consequently, the daily zonal mean, DW1 amplitude and phase are all estimated on a daily basis. Before the implementation of our technique, a comparative analysis between the instrument data sets is conducted. The analysis reveals temperature biases of up to 10K, which are removed to improve our estimates. To evaluate performance, our method is applied to a model atmosphere constructed from tidal fields obtained from the Global Scale Wave Model (GSWM). Performance results indicate that the DW1 is most effectively extracted from the background atmosphere and other tidal components when each latitude circle is well sampled and the local time sampling is evenly spaced. A comparison of our results to the GSWM and past observations support the conclusion that our method produces daily estimates of the DW1 that can be utilized for scientifically useful investigations of short term tidal variability.