{
  "annotation_id": "1559c891-8f95-4aea-bb60-e29764ef5b16",
  "date_created": "2026-03-02T18:00:50.482000Z",
  "date_modified": "2026-03-02T18:00:50.482000Z",
  "file_hash": "865685abfce53fae852d5eb7284d02d1d94b816218371a58fb54a502851a3338",
  "private": false,
  "record": {
    "abstract": "During the Eddy Experiment, two synchronous GPS receivers were flown at 1 km\naltitude to collect L1 signals and their reflections from the sea surface for\nassessment of altimetric precision and accuracy. Wind speed (U10) was around 10\nm/s, and SWH up to 2 m. A geophysical parametric waveform model was used for\nretracking and estimation of the lapse between the direct and reflected signals\nwith a 1-second precision of 3 m. The lapse was used to estimate the SSH along\nthe track using a differential model. The RMS error of the 20 km averaged\nGNSS-R absolute altimetric solution with respect to Jason-1 SSH and a GPS buoy\nmeasurement was of 10 cm, with a 2 cm mean difference. Multipath and retracking\nparameter sensitivity due to the low altitude are suspected to have degraded\naccuracy. This result provides an important milestone on the road to a GNSS-R\nmesoscale altimetry space mission.",
    "arxiv_id": "physics/0406025",
    "authors": [
      "G. Ruffini",
      "F. Soulat",
      "M. Caparrini",
      "O. Germain",
      "M. Martin-Neira"
    ],
    "categories": [
      "physics.ao-ph",
      "physics.ins-det"
    ],
    "doi": "10.1029/2004GL019994",
    "title": "The Eddy Experiment: accurate GNSS-R ocean altimetry from low altitude   aircraft",
    "url": "https://arxiv.org/abs/physics/0406025"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "c6b4d3d6-2a41-4f88-b2bb-203bd6a5e497",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}