Precise total electron content map monitoring in low latitude region

The need for accurate Global Navigation Satellite System (GNSS) positioning is necessary for GNSS applications such as Real-Time Kinematic (RTK), Precise Point Positioning RTK (PPP-RTK), etc. The ionosphere delay, especially in low latitude region, is a main cause of positioning error. The usage of electron maps in GNSS applications can help with the first ionosphere correction. The Global Ionosphere Map (GIM) is a large-scale service for the Total Electron Content (TEC) with a resolution of 2.5 for latitude and 5 for longitude which may not be proper to high resolution GNSS applications in the small or regional regions. Over the low latitude region, we apply the local TEC from 4 stations which has similar longitude to observe the differential TEC. Then, we generate the precise grid TEC maps from 18 GNSS stations with different resolution of grid for observe the appropriate values. The results are shown that the resolution of 1.5 for latitude and 3 for longitude has RMS 1.58 of TECu compare with the local TEC value, while GIM has RMS of 2.11 TECu.