RT Journal Article T1 Evaluation of Precise Point Positioning accuracy under large total electron content variations in equatorial latitudes A1 Rodríguez Bilbao, I. A1 Moreno Monge, Beatriz A1 Rodríguez Caderot, Gracia A1 Herraiz, M. A1 Radicella, S. M. AB The ionosphere is one of the largest contributors to errors in GNSS positioning. Although in Precise Point Positioning (PPP) the ionospheric delay is corrected to a first order through the `iono-free combination', significant errors may still be observed when large electron density gradients are present. To confirm this phenomenon, the temporal behavior of intense fluctuations of total electron content (TEC) and PPP altitude accuracy at equatorial latitudes are analyzed during four years of different solar activity. For this purpose, equatorial plasma irregularities are identified with periods of high rate of change of TEC (ROT). The largest ROT values are observed from 19:00 to 01:00 LT, especially around magnetic equinoxes, although some differences exist between the stations depending on their location. Highest ROT values are observed in the American and African regions. In general, large ROT events are accompanied by frequent satellite signal losses and an increase in the PPP altitude error during years 2001, 2004 and 2011. A significant increase in the PPP altitude error RMS is observed in epochs of high ROT with respect to epochs of low ROT in years 2001, 2004 and 2011, reaching up to 0.26 m in the 19:00-01:00 LT period. PB Elsevier SN 0273-1177 YR 2015 FD 2015-01 LK https://hdl.handle.net/20.500.14352/33856 UL https://hdl.handle.net/20.500.14352/33856 LA eng NO UCM NO Community of Madrid NO Department of Education, Language Policy and Culture of the Basque Government DS Docta Complutense RD 6 abr 2025