%0 Journal Article %T The Role of Spatial Gradient on Vertical Total Electron Content Extraction From Geodetic Very Long Baseline Interferometry Observation: Case Study CONT08 to CONT17‐L1 %A Etemadfard, Hossein %A Robert Heinkelmann %A Masoud Mashhadi Hossainali %A Harald Schuh %J Space Weather %@ 1542-7390 %D 2021