A new, long-term and global dataset of soil moisture measurements from space has been released to help us better understand the water cycle and climate, monitor agriculture and manage our water resources.
The amount of water held in global soils makes up only about 0.001% of the total water found on Earth, but still plays a crucial role in regulating plant growth, our weather and climate.
This is because soil moisture is a key variable controlling the exchange of water and energy between the land and the atmosphere: dry soil emits little or no moisture to the atmosphere and heats up more strongly during a hot day, thus intensifying heatwaves. Wet soils, on the other hand, have a cooling effect on the atmosphere.
Soil moisture data can be collected by satellites measuring microwaves reflected or emitted by Earth’s surface. The intensity of the measured signal depends on the amount of water in the soil. This information is important for improving short- and medium-term meteorological forecasting, as well as predicting hazardous events such as floods, droughts and heatwaves.
Scientists working under the soil moisture project of ESA’s Climate Change Initiative have harmonised data on soil moisture from different satellites dating back to 1978 to give us a long-term view of global soil moisture, as well as variations and trends in the water cycle.