Test of diurnal and semidiurnal tidal analysis of temperatures from SABER-like sampling of a realistic global model, CMAM-DAS

Abstract. Because the TIMED satellite orbit precesses slowly in local time, 3 degrees (12 min) per day, thus apparently covering all local times at low and mid latitudes in 2 months when ascending and descending nodes are included, there is a potential for determining migrating and non-migrating tides from temperatures. Many papers have been written on the subject, but none have taken a realistic model atmosphere with high time resolution and tested tidal analysis. The present paper contains results from a tidal analysis of a SABER-sampled global model, the Canadian Middle Atmosphere (data assimilated) Model, CMAM-DAS, which has hourly values, and compares these with analysis using the full model. Fits to 60 d intervals at the equator show reasonable agreement between full and SABER-sampled data analysis for mean, diurnal and semidiurnal tides, with or without inclusion of a linear detrend term. At 50° N where there is irregular coverage of local times, there are serious disagreements in all parameters except the background mean, and detrending has a significant effect.