On the TEC bias of altimeter satellites

NAVA BRUNO; AZPILICUETA FRANCISCO

Boston

Simposio; Beacon Satellite Symposyum; 2022

Boston College - ICTP

TOPEX/Poseidon, Jason-1, Jason-2 and Jason-3 altimeter missions have provided 27+ years of uninterrupted Total Electron Content (TEC) measurements since 1992, with unprecedented precision. Nevertheless, the issue of a possible systematic bias in the data was identified immediately after first TOPEX measurements were compared with measurements from other sources. The bias issue has increased in complexity because each new mission had its different bias. In this presentation, the results concerning the calculation of the (relative) biases between altimeter missions will be reported and the efforts made toward the determination of an absolute reference frame for TEC-related studies will be illustrated. In this respect, the importance of having co-located TEC estimates (from two altimeters and DORIS) will be underlined as a key factor for the identification of a “ground truth” TEC reference level. In particular, it will be shown how the origins of TEC reference frames, as defined by Jason 1 (data version E) and DORIS TEC estimates, coincide at the level of +/- 1 TECu (standard deviation), turning them as candidates to define an absolute reference level. Finally, the equations linking this absolute reference frame with the TEC levels of different altimeter missions, data versions and Global Ionopheric Maps (GIMs) will be reported, and the possible implications of the results obtained will be discussed.