Statistical analysis of mid-latitude long-lasting positive storm effects in the American Sector

Abstract:

Storm enhanced density (SED) features are an ionospheric manifestation of geomagnetic storms. Long-lived SED (LLSED) are a special category of SED distinguished by the prolonged enhancement lasting over 6 hours. In the present study we perform a statistical analysis of mid-latitude LLSED events in the American sector. We employee GPS total electron content (TEC) data processed by the Millstone Hill Observatory team and made available via the NSF CEDAR Madrigal database during the period 2000 to 2018. We found that out of the 665 geomagnetic storms between the years 2000 to 2018, only 8 percent of the storms are associated with LLSED development. A statistical analysis reveals that a majority (above 40 percent) of the LLSED events are associated with minor to moderate geomagnetic storm conditions, i.e., Dst above -100 nT. We will comment on the genesis of the LLSEDs and why they may be long lived. Mechanisms are yet to be determined.