DORIS contribution to the second yearly update of the ITRF2020

For the second yearly update of the 2020 realization of the International Terrestrial Reference Frame ITRF2020, i.e., ITRF2020-u2024, the International DORIS Service (IDS) submitted to the International Earth Rotation and Reference Systems Service (IERS) a set of 209 weekly solution files including station coordinates and Earth Orientation Parameters, covering the time period from 2021.0 to 2025.0. Three of the five IDS Analysis Centers (ACs) contributing to the new IDS combined solution delivered new series. These new series have been derived using new models and processing strategies for almost all of the current DORIS missions: Cryosat-2, HY2C, HY2D, Jason-3, Saral, Sentinel-3A, Sentinel-3B, and Sentinel-6A. In this paper, we present both the IDS AC and the IDS 25 combined solutions released for the ITRF2020-u2024. Then, we evaluate these series in terms of scale, geocenter and station positions with respect to (w.r.t.) ITRF2020-u2023 and in terms of Earth Orientation Parameters (EOPs) w.r.t. the IERS C04 series. The evaluation shows that, over the four-year time span, the IDS 25 scale values lie in a range of ± 2.5~mm with a trend of $$-0.10~mm/yr$$. Thanks to an improved modeling of the surface forces on the satellites, especially on Sentinel-6A, compared to the first IDS contribution to the ITRF2020, the new IDS 25 combined solution depicts smaller annual and 118-day signals in the geocenter coordinate time series. The evaluation also showed that the IDS 25 has an internal position consistency in North-East-Up components better than 6 mm per component. The EOPs from the IDS 25 combination were compared with the IERS C04 time series and the RMS agreement between these two time series is about 200 μ as for the $$x-$$ and $$y-$$pole coordinates.