Potential Contributions of the DESDynI Mission to Ionospheric Research

Abstract

Ionospheric propagation effects can have significant impact on the signal properties of low-frequency Synthetic Aperture Radar (SAR) systems. Recently, theoretical analyses of ionospheric distortions in low-frequency SAR signals have indicated a multitude of effects that are likely to affect the quality of SAR, interferometric SAR (InSAR), and polarimetric SAR (PolSAR) data [1-6]. Methods have been developed that are able to detect ionospheric effects in SAR data on a wide range of spatial scales and allow high resolution ionospheric mapping with high accuracy [3], [4], [7]. NASA’s Deformation, Ecosystem Structure and Dynamics of Ice (DESDynI) mission carries a spaceborne L-band synthetic aperture radar (SAR) with multiple polarizations to provide information on solid earth deformation, terrestrial vegetation structure, and ice dynamics. Besides providing improved performance and reliability of SAR for monitoring surface deformation, the L-band carrier frequency provides a means for mapping properties of the ionosphere with high spatial resolution and unprecedented spatial coverage. This paper describes the performance and benefits of DESDynI for ionospheric mapping. Specifically, we quantify the type, sensitivity, and accuracy of ionospheric measurements derived by a DESDynI-like system. We also analyze the achievable spatial and temporal sampling of ionospheric constituents at different areas on the globe and assess the value of the derived information for specific ionospheric research topics. After summarizing the physical origin of ionospheric signals in SAR data, Section 2 introduces several methods for extracting ionospheric information from DESDynI data. For each method, information on the measurement principle is provided and the range of extractable ionospheric parameters is determined. A first concept for an optimized ionospheric processor is shown that extends the performance of existing technology by maximizing the exploited information and increasing estimation robustness. An error analysis of the presented technology is shown in Section 3, where achievable accuracies of ionospheric measurements are analyzed for different retrieval methods. In Section 4 the benefit of SAR-based ionospheric data for ionospheric research is evaluated. In examples we examine its value for analyzing turbulent ionospheric processes in polar and equatorial regions, and for evaluating the structure of traveling ionospheric disturbances (TIDs) at various spatial scales.