Collaborative Research: CEDAR--Higher-Order Concentric Gravity Waves in the Northern Winter Thermosphere and Ionosphere

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This award will determine how the breaking of mountain waves affects space weather approximately 100-200 miles above the Earth’s surface. Mountain waves are created from the wind flowing over mountains. Mountain waves break and overturn when they get high enough above the mountains, similar to an ocean wave breaking on a beach. This process generates turbulence and large-scale waves which travel to higher heights above Earth. At 100-200 miles above the Earth’s surface, the neutral molecules in the waves collide with ions, which creates waves in the plasma called traveling ionospheric disturbances (TIDs). Some of these TIDs look like circular rings on maps of the total electron content from GPS receivers. TIDs can cause storms in the space weather that make it difficult to communicate with the satellites that orbit Earth. Understanding how energy and momentum are transferred through atmospheric regions via several gravity wave generation and dissipation cycles including secondary and tertiary gravity wave processes (multi-step vertical coupling processes) is important. This project includes 2 undergraduate students during the summertime for the 3-year duration of this grant. This research will therefore further the development and education of a globally competitive STEM workforce and will promote the progress of science. The team will share GPS/TEC signal processing routines which will benefit the community. The main objectives of this research are to determine 1) the gravity wave (GW) characteristics and sources of concentric traveling ionospheric disturbances over the quiettime winter continental United States (CONUS) and Europe through detailed observational studies, and 2) the “multi-step vertical coupling” (MSVC) processes which create higher-order GWs in the thermosphere from orographic forcing over the winter CONUS and Europe through detailed modeling studies. Because GPS/TEC observations are dense over the CONUS and Europe, these locations provide ideal locations to study these concentric TIDs. The team will identify and analyze concentric TID events observed by GPS/TEC during quiettime December-February for 5 winters during 2012-2023, and will simulate and analyze 6-9 one-week mountain wave (MW) events with the GW-resolving HIgh Altitude Mechanistic general Circulation Model (HIAMCM). They will address SQ1: What are the GW characteristics, locations, occurrence rates, and sources of the quiettime concentric TIDs observed by GPS over the winter CONUS and Europe? and SQ2: What are the simulated coupling processes by which orographic forcing over the CONUS and Europe creates higher-order concentric GWs in the thermosphere, and what are the large-scale changes that result in the thermosphere? The methodology includes HIAMCM, a ray trace model (the Model for gravity wavE SOurce, Ray trAcing and reConstruction (MESORAC)), and publicly-available NRLMSISE-00 and HWM14 models, MERRA-2 reanalysis data, GOES and EUMETSAT satellite data and GPS/TEC data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.