LAUSR

The water cycle components are being retrieved by an increasing number of satellite missions. However, the monitoring of the water cycle by satellite Earth Observations is still a challenge. Data sets suffer from numerous systematic and random errors and they are often not coherent with each other. We focus here on the Mediterranean basin, one of the regions most sensitive to climate change. A satellite-based analysis of the water cycle is undertaken using a collection of available satellite data sets. Our satellite data set combination uses a simple bias correction and weighted average, and provides a better water budget closure results than any raw satellite data set. Our almost purely satellite data set allows to better describe the full water cycle, not only over the continents, but also in the atmosphere and over the ocean. The limitation/possibilities of this satellite multi-component data set are described: (1) although improved, the water cycle is still not closed by satellite data and the satellite community should focus on this issue, (2) our combined data set shows good coherency with the ERA-I reanalysis which is the reference so far, both in terms of seasonal climatology and long-term trends. This means that, even if the water budget is not yet closed by satellite data, our monitoring of the water cycle using satellite observations is improving, even over complex regions such as the Mediterranean basin.