Daily, Seasonal, and Interannual Variations of the Migrating Diurnal Tide Component of Carbon Monoxide and Temperatures from Aura/MLS and SD-WACCM-X

The migrating diurnal tide (DW1) is the most dominant atmospheric tide in the mesosphere and lower thermosphere (MLT) region, and one of the main tidal modes behind DW1 is the upward propagating (1,1) Hough mode. In this work, we use Microwave Limb Sounder (MLS) measured carbon monoxide (CO) as a tracer for DW1 dynamics. By taking the difference from two different local time observations, near 2AM and 2PM within 24-hours, the daily DW1 and (1,1) Hough mode variations of CO and temperature are quantified throughout the MLS observation period. The latitudinal structure of COs DW1 component is highly correlated with temperatures DW1 component indicating that DW1-induced vertical motion drives the DW1 component of both CO and temperature. A tendency analysis using simulations from the Specified Dynamics Whole Atmosphere Community Climate Model with Ionosphere/Thermosphere eXtension (SD-WACCM-X) confirms this. From the daily (1,1) Hough mode amplitudes, monthly average and monthly variance of the (1,1) amplitudes are estimated. The analysis of the (1,1) amplitudes show that the seasonal and interannual variabilities of CO and temperatures (1,1) component from MLS observation and SD-WACCM-X simulation are very similar. Both their seasonality exhibits a semi-annual oscillation (SAO) with a primary peak in March equinox. Both their interannual variability show evidence of the quasi-biennial oscillation modulating their SAO amplitudes. Showing this allows us to perform in-depth analysis on the DW1 dynamics in the model.