A new Database of Water Level Time Series for Lakes, Rivers, and Wetlands from Multi-Mission Satellite Altimetry
Schwatke, Christian; Bosch, Wolfgang; Dettmering, Denise

Since many years satellite altimetry is becoming increasingly important for hydrology. The fact, that satellite altimetry, originally designed for open ocean applications, can also contribute reliable results over inland waters helps to understand the water cycle of the system earth and makes altimetry to a very useful instrument for hydrology.

In this poster, we present a new database with results from the new approach which provides water level time series for lakes, rivers, and wetlands from multi-mission satellite altimetry. For the estimation we use altimeter data from different missions such as Topex, Jason-1, Jason-2, GFO, Envisat, and Cryosat. Depending on the extent of the investigated water body we use 1Hz, high-frequent or retracked altimeter measurements. All altimeter systems are cross-calibrated in advance allowing us to merge all data and to use it as a single (virtual) altimeter mission. For the estimation of the water levels we use a Kalman filter approach applied to the grid nodes of a regular grid extended to the water body of interest. A robust mean value of the water levels is then taken to realize the water level time series. The time series have temporal resolutions of 30 days, 10 days or 1 day depending on the data coverage.

For validation of the time series, we compare our results with gauges. Hereby we achieve very high correlations between time series from altimetry and gauges.