DORIS-based VTEC at Altimetry Ionospheric Pierce Points (Jason-3, 2016–2024)

Description This dataset provides Vertical Total Electron Content (VTEC) estimates derived from Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) observations, evaluated at the ionospheric pierce points (IPPs) of satellite altimetry missions. Data characteristics Observation type: DORIS dual-frequency measurements Derived quantity: Vertical Total Electron Content (VTEC) Spatial reference: Altimetry ionospheric pierce points (IPPs) Temporal coverage: 2016–2024 (Jason-3 mission period) Temporal resolution: Second-level (aligned with altimetry data frequency) Data structure The dataset is organized by groups of satellite cycles. Each file corresponds to a continuous range of cycles and is named as: Cycle_aaa_bbb.pkl where aaa and bbb denote the starting and ending cycle numbers, respectively. Each file contains all observations within the corresponding cycle range. All files are stored in Python pickle (.pkl) format and can be directly read using pandas.read_pickle. The data are organized as pandas DataFrame objects. Columns obs_epoch Observation timestamp corresponding to the altimetry measurement epoch. ipp_lat Latitude of the ionospheric pierce point (IPP), in degrees. ipp_lon Longitude of the ionospheric pierce point (IPP), in degrees, within the range [-180°, 180°]. altimetry_vtec Reference VTEC value at the altimetry IPP location, derived from altimetry dual-frequency processing. pass_in_cycle Pass number within the satellite cycle. doris_vtec VTEC value obtained by interpolating DORIS-derived VTEC values from surrounding DORIS IPPs to the corresponding altimetry IPP location. doris_points_count Number of DORIS observations used in the interpolation for each IPP. doris_points_std Standard deviation of the DORIS VTEC values used in the interpolation, reflecting local variability. igs_gim_vtec VTEC value obtained by interpolating the IGS Global Ionospheric Map (GIM) grid to the corresponding IPP location. All VTEC values are expressed in TECU (Total Electron Content Units). In addition to the main data files, one auxiliary CSV file is provided to describe the temporal coverage of each cycle. The file includes the following fields: name – Identifier of the record cycle_number – Cycle number start_day, start_time – Start date and time of the cycle end_date, end_time – End date and time of the cycle pass_number – Number of passes within the cycle The auxiliary file facilitates mapping between cycle numbers and their corresponding time intervals, enabling easier temporal filtering and analysis. Notes The dataset is prepared to support ongoing research on ionospheric correction in satellite altimetry. The detailed methodology and validation are described in the manuscript “Assessment of DORIS-Based Ionospheric Delay Corrections for Satellite Altimetry”, which is intended for submission to Advances in Space Research. The same dataset can also be found in OpenADB at placeholder