Looking for Water with Microwaves
June 12, 2001
The Soil-Water Microwave Probe-L (SWaMP-L) is an instrument for estimating the amount of water in the top 10cm or so of soil. It works by measuring the extremely small amount of microwave radiation that is emitted by the soil (this is emitted by all objects). The intensity of this radiation falls when the soil is wet by rainfall or irrigation, and gradually increases as it dries out again. This technique has great potential for mapping soil moisture from space, which is thought to play a crucial role in weather and climate processes. Detailed analysis of the measurements may yield more valuable information, such as the soil's water content at depth, or the soil's hydraulic properties. This technique is being intensively studied at the University of Reading, England, using the SWaMP-L radiometer, and by other research groups around the world. Photo by Caroline Brookes.