Investigation of geomagnetic influences on the vertical coupling by gravity waves in the thermosphere/ionosphere

• Applicant: Dr. Paul Hartogh
• Subject Area: Atmospheric Science
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 273419358

Vertically propagating gravity waves (GWs) represent a major coupling mechanism that provides connections between the lower atmosphere and thermosphere/ionosphere (TI) system. GWs are an essential component of the climate of Earth. A large portion of them originate in the troposphere, and redistribute energy and momentum between the atmospheric layers upon propagation and dissipation. In the TI, molecular viscosity and ion drag are the major dissipation mechanism of GWs. Variations of the magnetic field in the TI change the refractive properties of the atmosphere (large-scale temperature and wind distributions), and alter dissipation by ion drag. The primary objective of this study is to investigate and quantify the influence of variations of the geomagnetic field on propagation and dissipation of GWs of lower atmospheric origin, and on their dynamical feedback on the TI. In particular, the role of GWs will be tested in linking a trend of weakening the geomagnetic field, and the unexplainably strong observed cooling of the thermosphere. The study will be performed using a comprehensive Coupled Middle Atmosphere-Thermosphere-2 (CMAT2) general circulation model that utilizes our state-of-the-art spectral nonlinear GW parameterization. Novel numerical simulations will be performed, and the results tested against existing and future observational datasets, including those from the SWARM satellites. Besides advancing and testing our fundamental understanding of the GW coupling, the results can potentially improve space weather predictions.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1788: Study of Earth system dynamics with a constellation of potential field missions
• International Connection: USA
• Co-Investigator: Dr. Alexander Medvedev
• Cooperation Partners: Professor Dr. Erich Becker; Professor Dr. Erdal Yigit