AUTOMATIC REGIONAL MAPPING OF TOTAL ELECTRON CONTENT USING A GPS SENSOR NETWORK AND ISOTROPIC UNIVERSAL KRIGING

Total Electron Content (TEC) is one of the most important parameters for observing and monitoring Space Weather. GPS Sensor Networks provide a cost-effective means for estimation of TEC. Due to sparsity of TEC measurements and possible outages of data, TEC may have gaps in temporal and spatial domain. In this study, an automatic spatial interpolation algorithm is developed for TEC mapping. The algorithm utilizes isotropic Universal Kriging with linear trend as its main technique for spatial interpolation. The theoretical semivariogram function that represents the spatial correlation structure of TEC is chosen to be from the Matern Family. The trend model parameters are obtained from TEC samples in closed form and the Matern parameters are estimated using Particle Swarm Optimization. The automatic structure enables TEC maps to be obtained with any desired time interval. The developed algorithm is applied to a midlatitude GPS Network and high spatial resolution TEC maps are obtained between May 2009 and May 2012 with 5 minute temporal update period. The algorithm is applicable to any midlatitude GPS network for analysis of temporal and spatial variability of ionosphere.