How Aquarius Works (00:01:02)[24-Feb-10] Most of us understand that the sun emits energy. We are very aware of that and we recognize the differences between day and night. But the earth also emits energy. In fact, everything that has a temperature emits energy. But the earth emits energy at different frequencies and different wavelengths than the sun. And when the earth emits that energy back, it emits most of that energy in what's called the infrared spectrum.
But some of that energy comes back at wavelengths that are micro-wavelengths. And the microwave lengths - the amount of energy that's emitted by the ocean - depends on the salinity. It is related to something we call the "brightness temperature". It all has to do with how much energy is emitted from the ocean back to the atmosphere, back out to space. And so if a satellite is sitting there, it's actually recording how much energy in that microwave segment is being emitted. And by the signal that it receives, it's able to "back out" (i.e., calculate) what the ocean salinity is. Credit: Susan Lozier.