Global Analysis of EnviSat Burst Echoes Over Inland Water

Abstract

Satellite radar altimeters have an established and increasingly vital role in monitoring the Earth's surface inland water resources. This paper analyzes two years of EnviSat burst echoes (which have 3.9-m nominal along-track separation) over rivers, lakes, and ephemeral water globally to assess the increase in monitoring potential afforded by the higher pulse repetition frequency (PRF) of the next generation of synthetic aperture radar altimeters and investigate spatial burst correlation. Burst echoes at 1800 Hz are successfully retracked with no waveform averaging. The conclusion is that the higher PRF allows detection and measurement of water bodies on a far finer spatial scale because water is a very bright reflector at Ku-band and land in general is relatively poor, with pools of water a few tens of meters across being successfully identified.

EnviSat altimetry for river and lakes monitoring

“…Global analysis of these 'individual echoes' (IEs) has revealed that even small pools of water can be identified, and height timeseries successfully retrieved from as few as 7 IEs [8]. As a further illustration of this, Figure 4 shows a timeseries generated from 3 years of Burst Echo data over the Uele River compared with the corresponding 18Hz timeseries.…”