GNSS-TEC

Notes

The global TEC data were derived from GNSS observation data in Receiver INdependent EXchange (RINEX) format obtained from a lot of regional GNSS reciever network all over the world. The number of GNSS stations reached more than 8800 in April 2019. These GNSS observation data were provided by many data providers (data provider list). If you use GNSS-TEC data for the purpose of scientific research, you should include the following acknowledgment text.

Example of acknowledgment text

Global GNSS-TEC data processing has been supported by JSPS KAKENHI Grant Number 16H06286. GNSS RINEX files for the GNSS-TEC processing are provided from many organizations listed by the webpage
(http://stdb2.isee.nagoya-u.ac.jp/GPS/GPS-TEC/gnss_provider_list.html).

Data description of global TEC map

We create four kinds of two-dinensional map (absolute TEC, ratio of the TEC difference (rTEC), detrended TEC (dTEC) and rate of the TEC index: ROTI) in geographic coordinates with time interval of 10 minutes using the RINEX files obtained from more than 9300 GNSS recivers all over the world (January 2020). The grid sizes of absolute TEC, rTEC, dTEC and ROTI maps are 0.5x0.5 degrees, 0.5x0.5 degrees, 0.25x0.25 degrees, and 0.25x0.25 degrees, respectively. Further, we perform the smoothing of each grid data with a boxcar average of 5x5 grid data for the TEC data in geographic latitude and longitude. For derivation of the absolute TEC values, we adapted the bias estimation method proposed by Otsuka et al. [2002]. The rTEC value was defined as a difference value from average TEC value of 10 geomagnetically quiet days every month, and the value was normalized by the absolute value of the average TEC. We also collect the RINEX files provided by many data providers in collaboration with the DRAWING-TEC project at NICT (https://aer-nc-web.nict.go.jp/GPS/DRAWING-TEC/).