Measuring Earth's Water
We've all heard that the oceans cover 70% of the Earth's surface area. But have you ever wondered how much water there really is on Earth? While you'd be hard-pressed to find anything beyond some vague estimates (about 321 million cubic miles in ocean water only according to the U.S. Geological Survey), a team of scientists is aiming to change all that by building a satellite that will be able to accurately assess all of Earth's water resources from space in a few years.
The KA band, as the satellite is known, will collect data at least 1,000 times more detailed than what is currently available and will improve scientists' understanding of the planet's water cycle which, in turn, should lead to the creation of more precise global-warming models. Cliff Yamamoto, a radar expert with the California Institute of Technology's Jet Propulsion Laboratory, is one of several scientists around the country test-driving an early prototype of the device to ensure that it is able to capture and interpret signals from a variety of water bodies.
"Climate-change models are really good at temperature (prediction), but not so good at precipitation," said Doug Alsdorf, an Ohio State geophysicist and one of the lead investigators on the project. Mounted on two radar units suspended at both ends of a 33-foot boom, the KA band satellite will bounce 200 pulses each millisecond off the Earth. The radars will form what is known as parallax, an important feature that will enable the precise measurement of the altitude of water surfaces to within an inch. This data will prove very helpful in estimating the water depth and flow of lakes, rivers and wetlands in remote parts of the world where little data is available.
Scientists such as Alsdorf hope that this satellite and similar ones being launched by other countries will improve our understanding of the hydrologic cycle because of its direct link to global warming: past fluctuations in the levels of greenhouse gases have prompted temperature swings that changed global water availability. This information will particularly come in handy for public-water planners in underdeveloped countries where even mild variations in the water supply could have drastic consequences.
Via ::Ponds to oceans (newspaper)