Calibration and Validation of Satellite Altimeters in Qinghai Lake

A campaign has been conducted in Qinghai Lake from July 10 to September 26, 2019. The destination of the campaign was to calibrate and validate the HY-2B and Sentinel-3A/B altimeters. A tide gauge was used to measure the water surface of the lake. A dedicated GNSS buoy was placed at the footprints of the altimeters and the tide gauge location, to measure the water surface difference between them. A static GNSS station was also placed as a reference for the GNSS buoy and then define the datum of the tide gauge. 11 radiosondes were released at the same location with the static GNSS station to achieve the wet troposphere delay (WTD). The WTD difference was 6.40 ± 5.95 mm compared with the static GNSS station derived ones. At last, the altimeters were calibrated using the tide gauge. The calibration results were + 3.38 ± 4.46 cm, −1.38 ± 4.09 cm and +2.88 ± 4.10 cm for HY-2B, Sentinel-3A and Sentinel-3B, respectively. The results showed good agreements with the cross-calibration and other calibration site.