Studies of large TEC gradients associated with equatorial plasma bubbles in the South American sector

Ionospheric plasma distribution around the low-latitude region is well known to be highly inhomogeneous, marked especially by the characteristic equatorial anomaly pattern. In addition, the development of equatorial plasma bubbles in the post-sunset local time sector further complicates the overall ionospheric plasma distribution profile in these regions. The steep total electron content (TEC) gradients associated with these space/ionospheric phenomena might pose some serious challenges to the establishment and operation of augmentation system(s) for GNSS application, particularly in aviation. We report our recent observational study of such steep TEC gradients using instruments in the Low-latitude Ionospheric Sensor Network (LISN).