Yet again, thank you NASA. As announced last month, their latest extraordinary earth-monitoring system is in orbit, commissioned and providing data: SMAP, the Soil Moisture Active Passive mission provides a high-resolution view of continuing changes in soil moisture across our world and allows understanding, analysis and planning in an unprecedented and fascinating way.
The map above is one of several already available:
These maps of global soil moisture were created using data from the radiometer instrument on NASA's Soil Moisture Active Passive (SMAP) observatory. Each image is a composite of three days of SMAP radiometer data, centered on April 15, 18 and 22, 2015. The images show the volumetric water content in the top 2 inches (5 centimeters) of soil. Wetter areas are blue and drier areas are yellow. White areas indicate snow, ice or frozen ground.
The soil moisture scale is in cm3/cm3 and demonstrates dramatically the often-forgotten fact that drylands, home to a third of our planet’s population, comprise over 40% of the land area.
As usual, the technology is extraordinary:
For an introductory description of how the radar and radiometer instruments conspire, see http://smap.jpl.nasa.gov/observatory/overview/. The NASA press release summarises the mission and the ways in which the data will be used:
Launched Jan. 31 on a minimum three-year mission, SMAP will help scientists understand links among Earth's water, energy and carbon cycles; reduce uncertainties in predicting climate; and enhance our ability to monitor and predict natural hazards like floods and droughts. SMAP data have additional practical applications, including improved weather forecasting and crop yield predictions.
A first global view of SMAP's flagship product, a combined active-passive soil moisture map with a spatial resolution of 5.6 miles (9 kilometers), is available at:
During SMAP's first three months in orbit, referred to as SMAP's "commissioning" phase, the observatory was first exposed to the space environment, its solar array and reflector boom assembly containing SMAP's 20-foot (6-meter) reflector antenna were deployed, and the antenna and instruments were spun up to their full speed, enabling global measurements every two to three days.
The commissioning phase also was used to ensure that SMAP science data reliably flow from its instruments to science data processing facilities at NASA's Jet Propulsion Laboratory in Pasadena, California, and the agency's Goddard Space Flight Center in Greenbelt, Maryland.
"Fourteen years after the concept for a NASA mission to map global soil moisture was first proposed, SMAP now has formally transitioned to routine science operations," said Kent Kellogg, SMAP project manager at JPL. "SMAP's science team can now begin the important task of calibrating the observatory's science data products to ensure SMAP is meeting its requirements for measurement accuracy."
Together, SMAP's two instruments, which share a common antenna, produce the highest-resolution, most accurate soil moisture maps ever obtained from space. The spacecraft's radar transmits microwave pulses to the ground and measures the strength of the signals that bounce back from Earth, whereas its radiometer measures microwaves that are naturally emitted from Earth's surface.
"SMAP data will eventually reveal how soil moisture conditions are changing over time in response to climate and how this impacts regional water availability," said Dara Entekhabi, SMAP science team leader at the Massachusetts Institute of Technology in Cambridge. "SMAP data will be combined with data from other missions like NASA's Global Precipitation Measurement, Aquarius and Gravity Recovery and Climate Experiment to reveal deeper insights into how the water cycle is evolving at global and regional scales."
It is, to me, wondrous that even a simple examination of the three successive images from which the one at the head of this post was taken reveals clear changes over the course of a few days – I can only begin to imagine what analysis of the real data will reveal.
The UN’s map and classification of global drylands drives home their importance to the way our planet works. The new SMAP data bring this to life in a dramatic way.
[SMAP image credit: NASA/JPL-Caltech/GSFC]