A Unified Lower Ionospheric Space Weather Diagnostic
Abstract
Forecasting space weather and space situation awareness are increasingly critical to protect defense assets in the polar region and satellites in orbit and to maintain reliable communications and radar systems in the face of space weather disturbances, both natural and anthropomorphic. In particular, the bottomside ionosphere is in need of diagnostic development, as current tools fall short of requirements. Ionosondes give a detailed ionospheric profile from 100 km up to the F2 peak but only at one location. They miss the D-region entirely (60−90 km) and cannot easily be deployed on a large scale. Very Low Frequency (VLF, 3−30 kHz) radio remote sensing provides diagnostic information about the D-region over a wide area with low-cost instruments, but it is difficult to quantify the ionosphere or achieve good spatial resolution using VLF alone. GNSS and satellite-based remote sensing is able to provide high spatial resolution over a wide area, but it also misses the D region and struggles with the E region where electron densities are lower. At the same time, the ionosphere is critical for High Frequency (HF) communications and over-the-horizon (OTH) radar. The E and lower F region guide the refractive path of HF energy, while the D-region is critical for absorption. Our current understanding of these regions is limited. For example, the ionospheric diagnostic we develop could, among other things, eventually replace current operational models of D-region absorption, the most prominent of which is known as D-Region Absorption Prediction (D-RAP), which is known to be inaccurate, and could be improved by a much more robust D-region nowcasting model. We propose to develop a diagnostic tool based on the unification of three techniques derived from previously funded efforts. The component techniques are- (1) Very Low Frequency imaging of the Dregion ionosphere using global lightning as a source of probe waves, (2) High Frequency (HF) beacons (transmitters and receivers) to probe the entire bottomside ionosphere and recover the E and lower F region profile, while also quantifying D-region absorption to constrain the VLF results, and (3) Groundbased and LEO CubeSat-based sensing of the total electron content (TEC) and rate of TEC change index (ROTI) which also provides a constraint for the HF results. The diagnostic tool, once validated and ultimately expanded, is envisioned to run continuously, with less than100 km and less than5-minute resolution, providing valuable information about the spatio-temporal development of ionospheric disruptions triggered by space weather. We propose to formulate and prove the concept for a wide-area, low-cost bottomside ionospheric diagnostic that could be deployed over otherwise inaccessible areas. Many ionospheric observation modalities exist, and a unified approach to ionospheric diagnostics can be a valuable breakthrough. Armed with this unified diagnostic, we will be able to address the spatio-temporal evolution of the ionospheric response to space weather. The scientific questions that will be addressed are -What is the best way to synthesize multiple disparate ionospheric observations in a single diagnostic. -How well are ambient conditions tracked by the ionospheric diagnostic across the entire bottomside -How do space weather disturbances present in the unified diagnostic, and how do they propagate across latitude, longitude and altitude -We intend to address these questions by focusing on nowcasting a large portion of Alaska, building a database of both ambient and disturbed conditions. In addition to these scientific questions, we will address validation using anthropomorphic disturbances generated by the HAARP HF facility in Alaska.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 29, 2024
- Source ID
- FA95502310164
Entities
People
- Morris B Cohen
Organizations
- Air Force Office of Scientific Research
- Georgia Tech Research Corporation
- United States Air Force