SAC D/Aquarius: no sólo salinidad marina, también humedad del suelo

A mediados del 2011 la CONAE (Comisión Nacional de Actividades Espaciales) asociada a la NASA puso en órbita el SAC-D, un satélite cuya principal misión era medir la salinidad de los mares con el instrumento AQUARIS diseñado por la NASA. Sin embargo, y gracias a un equipo de investigación de la USDA (United States Department of Agriculture), dicho instrumento resultó útil para mapear la humedad en los suelos. Por lo tanto, ahora es posible obtener mapas globales de humedad en la superficie terráquea. Esto permitiría comprender mejor el clima, predecir el tiempo, monitorear sequías, previnir de las inundaciones, mejorar la predicción de la productividad agrícola, mejorar las decisiones sobre la gestión del agua.

Launched June 10, 2011, aboard the Argentinian spacecraft Aquarius/Satélite de Aplicaciones Científicas (SAC)-D, Aquarius was built to study the salt content of ocean surface waters. The new soil wetness measurements were not in the mission's primary science objectives, but a NASA-funded team led by U.S. Department of Agriculture (USDA) researchers has developed a method to retrieve soil moisture data from the instrument's microwave radiometer.

The Aquarius measurements are considerably coarser in spatial resolution than the measurements from the upcoming NASA Soil Moisture Active Passive (SMAP) mission, which was specifically designed to provide the highest quality soil moisture measurements available, including a spatial resolution 10 times that offered by Aquarius.

Soils naturally radiate microwaves and the Aquarius sensor can detect the microwave signal from the top 2 inches (5 centimeters) of the land, a signal that subtly varies with changes in the wetness of the soil. Aquarius takes eight days to complete each worldwide survey of soil moisture, although with gaps in mountainous or vegetated terrain where the microwave signal becomes difficult to interpret.

Tom Jackson, principal investigator for the Aquarius soil moisture measurements and a hydrologist with USDA, said that his agency uses soil wetness information to improve crop forecasts. These forecasts not only help farmers and markets adjust their prices according to worldwide production, but also allow relief agencies to plan for food emergency responses. "There's a lot of precipitation data in our country, but outside the U.S. and Europe it gets pretty sparse," said Jackson. "By using soil moisture readings, we can better monitor the condition of soils."

Fuente: NASA's Aquarius Returns Global Maps of Soil Moisture.
Instrumentos a bordo del SAC D