The study investigates the impact of gravity waves (GWs) on the thermospheric circulation and composition using a high-resolution Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension (WACCM-X). Key findings include: 1. **Wave Propagation Anisotropy**: GWs are found to propagate anisotropically, with stronger eastward components at most altitudes, particularly in the upper atmosphere. This anisotropy is consistent with earlier findings and is crucial for accurately modeling hemispheric and seasonal asymmetries in wind reversal heights and strengths. 2. **Thermospheric Circulation**: The dissipation of GWs in the thermosphere leads to a net eastward forcing, which weakens the mean circulation in the winter hemisphere and enhances it in the summer hemisphere. This circulation change affects the distribution of thermospheric species, particularly atomic oxygen (O) and molecular nitrogen (N₂). 3. **Thermospheric Composition**: The column-integrated O/N₂ ratio, a measure of the relative abundance of atomic and molecular species, is reduced in both hemispheres due to the circulation change. The high-resolution simulation shows improved agreement with observations, suggesting that the resolved GW forcing accurately captures the dynamics of the thermospheric circulation. 4. **Model Comparison**: The high-resolution WACCM-X simulations reveal significant day-to-day variability in the mean circulation, which is driven by the variability of the driving force by waves. This variability is not well captured by the coarse-resolution simulations, highlighting the importance of high-resolution modeling for accurate representation of GW effects. 5. **Conclusion**: The study provides insights into how GWs influence the thermospheric circulation and composition, emphasizing the need for high-resolution models to accurately simulate these processes. The findings have implications for understanding the variability of thermospheric species and the dynamics of the upper atmosphere.The study investigates the impact of gravity waves (GWs) on the thermospheric circulation and composition using a high-resolution Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension (WACCM-X). Key findings include: 1. **Wave Propagation Anisotropy**: GWs are found to propagate anisotropically, with stronger eastward components at most altitudes, particularly in the upper atmosphere. This anisotropy is consistent with earlier findings and is crucial for accurately modeling hemispheric and seasonal asymmetries in wind reversal heights and strengths. 2. **Thermospheric Circulation**: The dissipation of GWs in the thermosphere leads to a net eastward forcing, which weakens the mean circulation in the winter hemisphere and enhances it in the summer hemisphere. This circulation change affects the distribution of thermospheric species, particularly atomic oxygen (O) and molecular nitrogen (N₂). 3. **Thermospheric Composition**: The column-integrated O/N₂ ratio, a measure of the relative abundance of atomic and molecular species, is reduced in both hemispheres due to the circulation change. The high-resolution simulation shows improved agreement with observations, suggesting that the resolved GW forcing accurately captures the dynamics of the thermospheric circulation. 4. **Model Comparison**: The high-resolution WACCM-X simulations reveal significant day-to-day variability in the mean circulation, which is driven by the variability of the driving force by waves. This variability is not well captured by the coarse-resolution simulations, highlighting the importance of high-resolution modeling for accurate representation of GW effects. 5. **Conclusion**: The study provides insights into how GWs influence the thermospheric circulation and composition, emphasizing the need for high-resolution models to accurately simulate these processes. The findings have implications for understanding the variability of thermospheric species and the dynamics of the upper atmosphere.