A survey of plasma irregularities as seen by the midlatitude Blackstone SuperDARN radar

Abstract

.[1] The Super Dual Auroral Radar Network (SuperDARN) is a chain of HF radars that monitor plasma dynamics in the ionosphere. In recent years, SuperDARN has expanded to midlatitudes in order to provide enhanced coverage during geomagnetically active periods. A new type of backscatter from F region plasma irregularities with low Doppler velocity has been frequently observed on the nightside during quiescent conditions. Using three years of data from the Blackstone, VA radar, we have implemented a method for extracting this new type of backscatter from routine observations. We have statistically characterized the occurrence properties of the Sub Auroral Ionospheric Scatter (SAIS) events, including the latitudinal relationships to the equatorward edge of the auroral oval and the ionospheric projection of the plasmapause. We find that the backscatter is confined to local night, occurs on ≈70% of nights, is fixed in geomagnetic latitude, and is equatorward of both the auroral region and the plasmapause boundary. We conclude that SAIS irregularities are observed within a range of latitudes that is conjugate to the inner magnetosphere (plasmasphere).

Observations of field-aligned ionospheric irregularities during quiet and disturbed conditions with EKB radar: first results

“…2c), the maximum number of ionospheric scatter corresponds to corrected geomagnetic latitude φ s = 63°. It differs significantly from the observations with midlatitude Blackstone SuperDARN radar (Ribeiro et al 2012) (detected at φ s = 54°). Geomagnetically, the Blackstone radar is located 5°-6°equatorward from the Yekaterinburg radar.…”

“…Study of statistical characteristics of the scattered signals with use of Super Dual Auroral Radar Network (Super-DARN) (Chisham et al 2007) is the subject of many papers, for example, the reviews (Chisham et al 2007;Milan et al 1997;Ribeiro et al 2012;Sotirelis et al 2005;Wild and Grocott 2008). The basic mode of SuperDARN radar is monitoring of the intensity and speed of the smallscale ionospheric irregularities.…”

Statistical Study of Nightside Quiet Time Midlatitude Ionospheric Convection

“…Here we clarify our definition of “midlatitude” and “subauroral.” The geomagnetic midlatitude ionosphere is typically defined as a buffer zone between the equatorial and auroral regions, with boundaries that vary with geomagnetic activity. The type of midlatitude ionospheric scatter we have selected for has been shown by Ribeiro et al () to lie equatorward of both the auroral region and the ionospheric projection of plasmapause boundary. Therefore, we consider the region of interest (52°–58° MLAT) under these quiet conditions to be subauroral and henceforth use the terminology subauroral instead of midlatitude to describe the convection.…”

Investigation of the temperature gradient instability as the source of midlatitude quiet time decameter‐scale ionospheric irregularities: 2. Linear analysis

“…They showed that the irregularities are excited on the equatorward wall of the midlatitude ionospheric trough in a region of opposed density and temperature gradients. Using 3 years of data from the second midlatitude SuperDARN HF radar located at Blackstone, Virginia, Ribeiro et al [2012] showed that the low-velocity Sub-Auroral Ionospheric Scatter (SAIS) associated with such irregularities is only seen at night and occurs on 70% of nights.…”

“…The scale length of ionospheric irregularities can range from a few centimeters to several kilometers. Several previous studies have employed statistical analyses to identify the source of F region irregularities [e. g., Ruohoniemi and Greenwald, 1997;Milan et al, 1997;Ballatore et al, 2000;Parkinson et al, 2003;Koustov et al, 2004;Kane and Makarevich, 2010;Kumar et al, 2011;Ribeiro et al, 2012]. High-frequency (HF) radars observe backscatter echoes from decameter-scale ionospheric irregularities with scale lengths on the order of 10 m [e. g., Oksman et al 1979].…”