PML researchers were part of the curation team for a recently-completed special issue of Remote Sensing devoted to calibration and validation of satellite-borne radar altimeters.
Over the ocean, these instruments provide highly accurate measurements of sea level plus records of wave height and wind speed. In recent decades their use over other surfaces has blossomed, providing a means to monitor water levels in tens of thousands of lakes, and delivering detailed maps of ice sheet topography over Greenland and Antarctica.
To achieve all this with an accuracy of a few centimetres requires careful monitoring of the instruments and of the atmospheric and oceanographic corrections.
The recent publication of the Editorial marks the completion of the special issue, which comprises 19 papers that cover many of the recent altimeters and all domains. The special issue was curated by five altimetry experts, including Dr Graham Quartly and Dr Francesco Nencioli (formerly of PML).
Dr Quartly said: "With growing concern about climate change and its impact on sea level, wave conditions, melting of ice sheets and the availability of freshwater in lakes, it is more critical than ever that we have accurately calibrated data spanning many decades.
"This means that each altimeter mission needs its own dedicated effort to bring them all into line, and this collection of papers showcases the frontier in validation activity."
Radar altimeters operate over all of the Earth's surfaces, giving precise information on the height of the surface, and also wind speed and wave height over the ocean or sea ice thickness where relevant. (SH: Sea Surface Height, WSH: Water Surface Height, SWH: Significant Wave Height)