Space – the final frontier. It’s also about to become the next frontier for measuring soil moisture.
That’s because as of January 29, NASA is planning to launch its Soil Moisture Active Passive (SMAP) satellite, which will be able to produce the most accurate, highest resolution global maps ever obtained from space. The satellite can detect and map whether the ground is frozen or thawed. More crucially, it will be able to determine the moisture present in the top two inches of the planet’s soils.
“With data from SMAP, scientists and decision makers around the world will be better equipped to understand how Earth works as a system, and how soil moisture impacts a myriad of human activities, from floods and drought to weather and crop yield forecasts,” says NASA spokeswoman Christine Bonniksen. “SMAP’s global soil moisture measurements will provide a new capability to improve our understanding of Earth’s climate.
Studying a soil’s moisture content and its freeze/thaw has several benefits, Bonniksen says. It will allow researchers to better determine soil moisture’s impact on both short-term regional weather and longer-term global climate. SMAP data will also enhance confidence in projections of how Earth’s water cycle will respond to climate change.
“Assessing future changes in regional water availability is perhaps one of the greatest environmental challenges facing the world today,” says Dara Entekhabi, SMAP science team leader at MIT.
Entekhabi says that today’s computer models disagree on how the water cycle – precipitation, clouds, evaporation, runoff, soil water availability – will increase or decrease over time and in different geographies. SMAP’s higher resolution data will improve these models to make both daily weather and longer-term climate predictions. SMAP will also be able to advance the ability to monitor droughts and predict floods.
The satellite contains an active radar that acts like a flash camera. However, instead of transmitting visible light, it pulses microwaves that can pass through clouds and moderate vegetation cover straight to the ground. It then measures how much of that signal is transmitted back. Microwave radiation is sensitive to how much moisture contained in the soil.