Development of a substorms catalog including the MPB observed at Panagjurishte station, Bulgaria

In this work the first results of the creation of a substorms catalog including the mid-latitude positive bays (MPB) registered at the Bulgarian station Panagjurishte (∼37° GMLat, ∼97° GMLon) are presented. MPB index characterizes the mid-latitude effect of substorm, which developed at auroral latitudes, and it is associated with the substorm current wedge.

The work went in several lines. First, the catalog design and content were taken. Second, tools of data processing have been developed. Third, substorms during two months, namely January and February 2013 were identified. And finally, data processing was implemented and the characteristics of the positive bays were determined.

The obtained data and their visualizations were put in a convenient folder and file structure, ftp positioned.

Relative contributions of large-scale and wedgelet currents in the substorm current wedge

We examined how much large-scale and localized upward and downward currents contribute to the substorm current wedge (SCW), and how they evolve over time, using the THEMIS all-sky imagers (ASIs) and ground magnetometers. One type of events is dominated by a single large-scale wedge, with upward currents over the surge and broad downward currents poleward-eastward of the surge. The other type of events is a composite of large-scale wedge and wedgelets associated with streamers, with each wedgelet having comparable intensity to the large-scale wedge currents. Among 17 auroral substorms with wide ASI coverage, the composite current type is more frequent than the single large-scale wedge type. The dawn-dusk size of each wedgelet is ~ 600 km in the ionosphere (~ 3.2 R _E in the magnetotail, comparable to the flow channel size). We suggest that substorms have more than one type of SCW, and the composite current type is more frequent.