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If we measure the Earth from the ground, we can a get a good local picture of what is going around us. But if we want to measure larger portions of the Earth, then we’ll need to use remote sensing. Remote sensing measures the Earth and its features without making physical contact. We can gather data from entire continents over longer time periods so we can look at how the Earth is changing. NASA uses specialized aircraft and sophisticated satellites to gather data using both passive and active remote sensing methods. Passive remote sensing measures the natural energy, or radiation, of the Earth. Active remote sensing gathers data by actively sending out signals that interact with the target of interest. Using both active and passive remote sensing techniques, NASA can look at soil moisture maps to monitor drought, estimate snowpack in areas where snow is crucial for freshwater, measure the change in ice sheets and sea level, tracking storms that could impact human lives, and observing how precipitation changes affect where we get our freshwater. The Global Precipitation Measurement mission helps fill in the gaps where ground measurement isn’t enough. Places with rugged terrain can block the signals from ground radars. The oceans are too vast to cover with enough ships and measurement stations on the surface, and places without the network of instruments needed to measure freshwater for people and agriculture. We can then unify the measurements to create a consistent and accurate picture no matter where we are. Because satellites get more complete coverage than ground-based instruments, we can use remote sensing to better see how the whole Earth is changing over time. With a long data record we can make better predictions about the water cycle, the climate, and the impact on humans.
[ wind, thunder, rain ] [ wind, debris flying ] [ tree splitting, insects swarming ] [ debris falling, bubbling, airplanes ] [ music ] By observing our Earth from above, we get a much better understanding of what is happening on the surface, in the atmosphere, underground, over the globe, and in our own backyard.
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