Quantifying the Relative Importance of Upward Propagating versus Thermospheric Tides

This study quantifies the relative importance of in-situ forced tides compared to upward propagating tides in the thermosphere, as well as examines the impact of solar and geomagnetic activity on these in situ generated tides using the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (SD-WACCM-X). We employ Hough Mode Extensions (HME) to separate upward-propagating tides originating in the troposphere and stratosphere from tides generated in situ within the thermosphere. To understand the influence of solar and geomagnetic conditions on the thermospheric tides, we compare standard SD-WACCM-X simulations with control simulations where geomagnetic (Kp) and solar (F10.7) activity levels are fixed at lower values. Focusing on 2014, a year characterized by elevated solar and geomagnetic activity, we analyze how these forcing mechanisms alter tidal amplitudes and latitudinal structures. The model simulations are validated by comparison with independent neutral density tide observations from CHAMP satellite data at approximately 390 km altitude from 2002–2004 (F10.7 =140 sfu). The results highlight the critical role of thermospheric forcings in shaping tidal dynamics, which has implications for the forthcoming DYNAMIC and GDC missions.