Center for Astrophysics Research and Technologies Seminar Series
Ionospheric Variability due to Solar Influences: Solar Storms, Eclipses, Flares, and the 11-year Solar Cycle
Presented by Anthea Coster, MIT Haystack Observatory
There are a myriad of mechanisms that produce variability in the ionosphere, the ionized region of the Earth's atmosphere that extends from approximately 90 km to 100 km. The focus here is on the variability driven by solar influences, for example, the variability introduced on the ionosphere from solar storms, eclipses, flares, radio bursts, and the 11-year Solar Cycle. Some of this variability can have a profound influence on Global Navigation Satellite System (GNSS) systems, and is an important driver of space weather effects. For example, during large solar storms, a feature known as storm enhanced density (SED) that is associated with large ionospheric gradients is frequently observed across the continental United States. Large gradients in the total electron content (TEC) make it difficult to correctly predict the ionospheric range correction, thereby impacting high precision real-time positioning applications such as autonomous vehicle control, marine positioning, and emergency response. A specific example was during the great solar storms of October 29th and 30th, 2003, when the FAA's Wide Area Augmentation System (WAAS) was adversely impacted for 15 hours on the 29th and 11.3 hours on the 30th [Doherty, et al., 2004]. These large solar storms also produce what is referred to as large scale traveling ionospheric disturbances (or TIDs), and examples from the March 17 2013 and 2015 solar storms will be shown.
While not as large as solar storms, we will also describe the influence of solar flares and solar eclipses on the ionosphere utilizing GNSS TEC data. These data are freely accessible utilizing NSF's CEDAR Madrigal database. Madrigal provides TEC data from the year 2000 until the present binned into 1-degree bins of latitude and longitude for every 5 minutes (http://cedar.openmadrigal.org/). In addition, we will illustrate the new line of sight (LOS) TEC data product which contains a significant amount of additional geophysical information that is not readily available with standard binned vertical TEC projects. Currently, data from ~ 6000 receivers around the globe are processed at MIT Haystack on a daily basis, corresponding to almost 100 million line-of-sight (LOS) TEC measurements.
2:00 pm, Thursday, April 11, 2019
PAIS-2540, PAIS
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