Global Distribution, Sources and Effects of Large Density Gradients

Team Chair: Rod Heelis
Next Team Meeting: Team Meeting #1, February 18-19, 2008, Space Science Center, Waterview Science and Technology Center, University of Texas at Dallas, Richardson, Texas, 75025
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Target Description: Large electron density gradients in the middle and low latitude ionosphere have a major impact on a variety of technological systems, including navigation, communications, and radar. Recent methods for imaging ionospheric electron density structure using ground-based and space-borne instruments are providing a new observational context for measurements that capture these gradients. Understanding the physical causes of large gradients often requires a "systems-level perspective" of the coupled Sun-Earth system, involving solar-wind, magnetospheric, ionospheric, and thermospheric processes. The interaction of these various physical systems to create the ionospheric features of such major societal impact represents an important frontier of scientific knowledge and will require imaginative new methods, models, and combinations of data to understand and predict. The focus of this topic is middle to low latitudes regions (broadly defined) where technological systems are concentrated.

Goals and measures of success: The goal of soliciting these investigations is to produce an improved scientific understanding and characterization of large electron density gradients in the Earth's middle and low latitude ionosphere, leading to improved models that can generate predictions of societal value. We expect to produce a better characterization of the temporal and spatial scales, magnitudes, and global distribution of large gradients, under what conditions they form, and the physical understanding necessary to model such features as a function of the geophysical conditions that create them. Improved prediction capability should be established.

Types of solicited investigations: Proposals that address this topic are expected to exploit observational, theoretical, and modeling approaches that improve characterization and scientific understanding of large electron density gradients in the middle and low latitude ionosphere. The research objectives can address one or more of the following areas: 1) improved characterization of the global distribution, dynamics, and lifetimes of large gradient features; 2) theoretical analyses that elucidate how they are generated and related to conditions in the broader geophysical environment; 3) model development of appropriate spatial and temporal resolution to simulate the relevant physical processes; and 4) establishing new empirical or theoretical relationships that will lead to improved modeling and prediction. It is expected that a significant number of submitted proposals will deal with cross-disciplinary topics involving observations and modeling of solar wind, magnetospheric, ionospheric, and thermospheric coupled processes.