A Nonlinear Numerical Model for Comparative Study of Acoustic‐Gravity Wave Propagation in Planetary Atmospheres: Application to Earth and Mars. Issue 8 (26th August 2022)

• Record Type: Journal Article
• Authors: Srivastava, Sarthak; Chandran, Amal; Thiemann, Edward M. B.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 8(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-26
• Subjects: Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2021JE007156
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: A two‐dimensional nonlinear numerical model has been developed to study atmospheric coupling due to vertically propagating acoustic gravity waves (AGWs) on different planets. The model is able to simulate both acoustic and gravity waves due to inclusion of compressibility. The model also considers dissipative effects due to viscosity, conduction, and radiative damping. The hyperbolic inviscid advection equations are solved using the Lax‐Wendroff method. The parabolic diffusion terms are solved implicitly using a linear algebra‐based Direct method. The model is validated by comparing numerical solutions against analytical results for linear propagation, critical level absorption, and mountain wave generation over an isolated hill. Acoustic wave generation in Martian atmosphere due to a pressure pulse is also demonstrated. A case study of tsunami‐generated AGWs is presented for the 2004 Sumatra earthquake whereby the model is forced through tsunamigenic sea‐surface displacement. The properties of simulated AGWs closely match those derived from ionospheric sounding observations reported in literature. Another application for Martian ice cloud formation is discussed where gravity waves from topographic sources are shown to create cold pockets with temperatures below the CO2 condensation threshold. The simulated cold pockets coincide with the cloud echo observations from the Mars Orbiting Laser Altimeter aboard Mars Global Survey spacecraft. Plain Language Summary: Gravity waves (GWs) are oscillations in the atmosphere that are responsible for a variety of effects related to disturbances in wind patterns and changes in plasma in the upper atmosphere. These effects are important enough that GWs need to be properly accounted for in the climate models of planets. However, the typical wavelengths of GWs are much smaller than the typical resolutions of these climate models leaving no choice but to use coarse approximations. Several models have been developed independently to perform detailed computer simulations of GWs on different planets, differing in their capabilities and limitations. There is a lack of a general model that can be used to simulate GWs on any planetary atmosphere. Here, we present such a model that can be very useful for performing comparative studies of GWs on different planets. We validate the model by showing agreement between simulations and predictions from theory. We then apply our model to two case studies. The first case shows simulation of GWs from the 2004 Sumatra tsunami. The simulated wave speeds and frequencies match the observations published elsewhere. The second case uses the model to identify regions of orographic CO2 ice cloud formation on Mars. Over 90% of the cloud echo observations are seen to coincide with the cold air pockets simulated by the model. We demonstrate that the presented model can serve as a versatile tool to simulate acoustic gravity waves on different planets. Key Points: A two‐dimensional nonlinear compressible model is presented for simulation of acoustic and gravity waves (AGWs) in different planetary atmospheres The model is validated, and applied to simulate AGWs generated from the 2004 Sumatra tsunami, and identify CO2 ice cloud regions on Mars The model is well‐suited to perform comparative studies of gravity wave propagation, growth, and dissipation on different planets