Scientists at NASA's Goddard Space Flight Center may have found a method of predicting drought conditions months in advance. The catch is, the method is currently based on a set of computer models. Now the test is to see if what works well on a virtual Earth can be translated into real-world predictive power.
In the Global Land-Atmosphere Coupling Experiment (GLACE), Koster and colleagues duplicated the same experiment using 12 different computer models from around the world. With each model researchers compared the rainfall behavior in two sets of simulations: one in which the soil moisture differed between the simulations, and one in which all simulations saw the same soil moisture. Any increase in rainfall agreement in the second set of simulations shows an impact of soil moisture on the rainfall.
Although the model results differed, the simulations also shared certain common features. By averaging together all the findings, the researchers identified the common features, or "hot spots" where soil moisture influences rainfall the most.
The next step is to work through satellite data to confirm the simulation results. The key will be determining soil moisture levels in key "hot spot" locations. The Aqua satellite (part of NASA's Earth Observing System satellite network) can measure soil moisture only down a couple of centimeters; the upcoming Hydrosphere State mission, set to launch in 2009, will be able to measure global soil moisture down to 5 centimeters.