Optimal Reconstruction of Gravity Wave Parameters from GNSS-TEC-derived TID Images
Abstract
Approved for Public Release Gravity Waves (GWs) are ubiquitous perturbations of neutral atmosphere ranging from the Earth#s surfaceto the exosphere. These perturbations in winds drive the ionospheric plasma up and down the field lines, creating plasma density perturbations called Traveling Ionospheric Disturbances (TIDs). The TIDs predominantly impact the bottom-side ionosphere altering the HF propagation relying on reflection off the bottom side ionosphere. GWs are extremely difficult to measure directly, so measuring TIDs instead can serve as an observational proxy to observing the source -GWs. The ubiquity and special coverage of ground-based geodetic Global Navigation Satellite System (GNSS) receivers observing slant Total Electron Content (TEC) is enabling a burgeoning fieldof GNSS TID estimation. This observational modality is becoming ubiquitous in observing ionospheric variability driven from below, that is from GWs. The overarching goal of this project is to quantify the impacts of the GNSS TEC signal processing algorithms on inferring the TID parameters and thus the physical conclusions about the bottom-side ionosphere and the underlying GW parameters.This project has three objectives: (1) to optimize the creation of TID images, quantify the relationship between TID-inferred horizontal parameters and the underlying GWs. (2) To quantify the possibility of the maximum momentum flux altitude from the height of TID projection. (3) To devise and validate ionospheric maps of maximum electron perturbation height based on the inferred TID parameters.Wewill employ a forward physics-based model consisting of HI Altitude Mechanistic general Circulation Model (HIAMCM) and Model for gravity wavE SOurce, Ray trAcing and reConstruction (MESORAC) driving the ionospheric Sami is another model of the ionosphere (SAMI3) model. GWs from HIAMCM+MESORAC drive ionospheric perturbation in SAMI3, which we will utilize to generate synthetic slant TEC profiles mimicking ground-based GNSS receivers. We will quantify the accuracy of the different TEC processing algorithms and the effects of the moving GNSS-TEC line-of-sight on the reconstructed TID field and TID horizontal parameter estimation (period, horizontal wavelength, phase speed, and direction of propagation). We will devise and quantify the accuracy of a new algorithm for optimal TID imaging with a variable IPP projection height. The variable projection height is of a vital importance because the peak heigh of the density perturbations are controlled with the time-space dependent background density profile and GW parameters. TIDs at the optimal projection height will be then used to estimate the vertical wavelength, which in conjunction with the horizontal parameters and the projection height are used to estimate GW parameters using the GW dispersion relation. This research will enable characterizations ofthe bottom-side ionospheric variability and the impact of this variability on the propagation of radio waves from VLF-GPS frequencies. The project outcomes have direct path applications by leveraging near-real-time GNSS data streams thus providing operational ionospheric specification.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 08, 2024
- Source ID
- N000142412329
Entities
People
- Sebastijan Mrak
Organizations
- Johns Hopkins University
- Office of Naval Research
- United States Navy