A Decade of Global River and Lake Heights from ESA Altimeter Missions
Philippa A. Berry(1) , James D. Garlick(1) , Jennifer Freeman(1) , Jerome Benveniste(2) , and E. Lucy Mathers(1)
De Montfort University,
Leicester LE1 9BH,
(2) ESA ESRIN, Via Galileo Galilei, Frascati, Italy
The ESA altimeter missions ERS1, ERS2 and Envisat have gathered a unique dataset over the earth’s land surfaces, including inland water. Key to this success is the mode switching capability, which has allowed the instruments to maintain lock on the surface over rapidly varying topography, and thus gather data over lakes and rivers even in mountainous terrain. To exploit this unique dataset, a processing scheme has been developed to extract inland water heights from lakes and rivers on a global scale. Key to the success of this scheme has been the development of new retracking algorithms, which allow the determination of inland water heights from a range of echo shapes. This now permits derivation of historical time series of river and lake heights from thousands of targets worldwide. These will be disseminated over the next 12 months. In an exciting new development, the near real time capability of the RA-2 is harnessed to generate measurements on a timescale of a few days over rivers and lakes on a global scale. These data are now made available online through a web based delivery service.
This paper presents an overview of the river and lake system, shows the global distribution of measurements available from both the near-real-time and historical time series, and demonstrates the unique capabilities of both the Envisat RA-2 and the processing scheme to measure heights of the earth’s inland water surfaces.