Irregularity Diagnostics by Digital Ionosondes

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

The contributions of ionosondes as standard observatory network instruments are already widely recognized in aeronomy and its current focus on space weather. Modern digital research ionosondes such as the dynasonde expand the variety, resolution and dynamic range of the products, but also of the noise. This 'noise' is, in fact, evidence of the very essence of space weather in the upper atmosphere: It is a signature of the irregular and dynamic state of the region. In this project, some theoretical developments that have already demonstrated substantial successes of this kind are to be extended and applied to dynasonde digital ionosonde measurements. Three new products include: 1) Statistical parameters to quantify the prevailing small-scale ionospheric irregularities, such as the amplitude and the index of a power-law spatial spectrum usually applicable in the range of scales extending from about the radio wavelength to at least the radio Fresnel scale. 2) An outer scale of the small-scale irregularities, when this can be distinguished from still larger irregularities attributable to Atmospheric Gravity Waves (AGWs). 3) Local spatial diversity of these quantities, using the 'all-sky' view characteristic of ionosondes. This can be very important especially in equatorial and auroral regions, during conditions of intense large-scale structuring. The PIs will use data from a dynasonde operating at EISCAT's auroral location; from another at the mid-latitude Bear Lake Observatory operated by Utah State University; and from an equatorial campaign, 'Project CONDOR' of March 1983 for the above studies.