Dartmouth Events

Abstract: Recent improvements in the processing of global navigation satellite system (GNSS, eg. GPS) Total Electron Content (TEC) data have led to the availability of new TEC data formats and products.  MIT Haystack Observatory is now downloading data from ~6000 globally distributed GPS receivers and processing ~100 million line of sight TEC values per day.  Line of sight TEC data for each receiver and for each satellite will soon be available in hdf5 format through the on-line Madrigal database.   In this talk, we will introduce a few of the new Madrigal data products and present three scientific studies that utilize these new tools to view space weather phenomena with more precision and detail than previously possible.  The first study involves observations of large scale traveling ionospheric disturbances (LSTIDs) following the 17 March 2015 geomagnetic storm.  Global LSTIDs are observed using the new differential TEC product.  They are launched in both hemispheres and from both the day and nightside auroral region.  The differential TEC data clearly shows LSTIDs crossing the equator and entering the other hemisphere, with a merging region in the center.  The second study we report on involves the overlaying of scintillation parameters onto TEC maps in Antarctica.  Multiple years of scintillation data from GPS receivers at South Pole Station and at McMurdo Station have been incorporated into the Madrigal database.  A statistical analysis based on this data has been completed, and the correlation of measured scintillation with a variety of geomagnetic indices (Bz, Dst, and Kp) has been examined.  Finally, a third study shows the overlaying of GPS TEC maps onto all-sky camera movies in both the Arctic and Antarctic.  These movies show evidence of the complex evolution of aurora that lead to multiple instances of GPS loss of lock.

As we look to the future and ask how scientific understanding in our field will evolve, it is clear that some of the next steps are to try to fill the data gaps, to find processes to more easily merge the different data sets, and to address the problem of limited real time data.   By 2023, there are predicted to be more than 160 GNSS satellites in orbit broadcasting 400 different signals.  There is a real possibility of continuous high precision global coverage of ionospheric parameters, allowing for space weather now-casting.  The question is what needs to be done now to make this goal achievable.