NA-TEC maps cover a wide region of 60-130 deg W and 24-54 deg N (30-65 deg N in geomagnetic latitude), and have a spatial resolution of 1.05x1.05 deg in latitude and longitude (0.15x0.15 deg with 7x7 pixel smoothing) and a temporal resolution of 30 seconds.
Homepage: http://stdb2.stelab.nagoya-u.ac.jp/GPS/IGS/