Workshop 2018
Sandra Blevins - Survey of solar flare signatures in the upper ionosphere with GNSS and GOES observations: a case study - October 29, 2018 • 34 Views
Global navigation satellite system (GNSS) phase measurements of the total electron content (TEC) and ionospheric delay are sensitive to sudden increases in electron density in the layers of the Earth’s ionosphere. These sudden ionospheric disruptions, or SIDs, are due to enhanced X-ray and extreme ultraviolet radiation from a solar flare that drastically increases the electron density in localized regions. SIDs are solar flare signatures in the Earth’s ionosphere and can be observed with dual-frequency GNSS (L1 = 1575.42 MHz, L2 = 1227.60 MHz) receivers that probe the upper (F-region) ionosphere. Data from over 500 solar flare events, spanning April 2010 to July 2017, including GOES C-, M-, and X-class solar flares at various intensities, were collected from the Space Weather Database Of Notifications, Knowledge, Information (DONKI) developed at the NASA Goddard Space Flight Center (GSFC) Community Coordinated Modeling Center (CCMC). Historical GOES satellite (NOAA) X-ray flux (NASA GSFC CCMC integrated Space Weather Analysis system (iSWA)) time series data are available for all solar flare events of the sample set. We use GNSS data archived at the NASA GSFC Crustal Dynamics Data Information System (CDDIS) to characterize the F-region reactions to the increased ionization, complementing space-based X-ray observations (GOES). CDDIS provides decades of historical GNSS data with 24-hour coverage and temporal resolution of 30 seconds from over 500 stations. In a preliminary case study we choose 100 stations, spanning 20 countries at a variety of geographic locations, with coverage for one X6.9 class solar flare event. An ionospheric group delay feature was found present in 36% of GNSS carrier phase observations, and the station locations with pulse features correspond to global regions of relatively high TEC during the time of the flare event. The extracted data and results of this study will be archived and made available at the CDDIS, in hopes of providing easily accessible data useful for statistical studies involving solar flare events and SIDs to the GNSS and space weather communities. The case study, sample set, data extraction and analysis methods, and future work will be presented.

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