Lidar is a lot like radar, but it uses lasers instead of radio waves. Many studies of sea level rise still use radar elevation data collected by the space shuttle in 2000. But radar isn’t precise enough to separate treetops from terra firma, and a patch of pines or cluster of condos can easily exaggerate the elevation. Radar blankets an area in radio waves, then measures how long it takes the waves to bounce back. The problem stems from limitations in the technology typically used to measure elevation: radar. “Obviously, you can’t use that,” he says. In tropical forests, says Vernimmen, these misinterpretations can be off by 20 meters or more. The problem, according to the new study by Ronald Vernimmen and Aljosja Hooijer, two data analysts working on flood risk in Southeast Asia, is that time after time, the measurements of coastal elevation that scientists feed into their models have been wildly inaccurate. As with all of science, the accuracy of these predictions is only as good as the data flowing into them. It’s not that the water is rising faster it’s that the land was lower to begin with.Ĭalculating when a rising sea will flood any one place involves a lot of math: you need to know the height of the water, the range of the tide, the elevation and slope of the land, the pace of sea level rise, and how much the land itself is rising or falling, among myriad other factors. As new research shows, in many places, sea level rise will cause coastal flooding and other disruptions much sooner than anyone realized. These projects are hefty, expensive, and slow.īut they may need to pick up the pace. J| 750 words, about 3 minutes Share this articleĪround the world, communities are bracing for sea level rise: the Netherlands is stabilizing its dikes, Senegal is relocating neighborhoods, Indonesia is moving its entire capital city. Photo by AgeFotoStock/Alamy Stock Photo Coastal Flooding Will Be More Extensive Sooner than Scientists Thought Updated, more accurate data gives a new look at the effects of sea level rise. As measurements of coastal elevation improve, those projections are getting more refined, which may require decision-makers to update their plans. Just leave the water immediately when you witness this phenomenon, and you’ll avoid potentially deadly riptides, something even experienced swimmers should avoid.Preparing for the effects of sea level rise depends on having good data. So, if you see square waves in the ocean, they are as dangerous as you’ve heard, but mostly in the deep. If you happen to be in a small boat and not very far out, then it is likely that you are going to be okay. However brief, when two weather systems are colliding like this, you can get waves as high as 10 feet, and the design of ships, fine for a single weather system, are in very real danger of rolling when this occurs. In fact, scientists around the globe are involved in square wave studies looking at dangerous cross seas and the occurrence of rogue waves. When ships observe a cross sea, however, it is a different story. Plus, they don’t tend to last very long, sometimes dissipating in minutes. As they form near the coast, in areas where tourists gather, swimmers will have been warned in advance, and these ripples can even be quite safely observed in depths of water only inches deep. Most swimmers who see square waves in the ocean are going to be in relatively shallow water and have a good chance of getting out of it once they’ve noticed. While the rip tides CAN pose a danger to swimmers, most of the information you see in this regard is a bit exaggerated in order to get your attention. Cross waves are more of a danger to ships than to people While it manifests as an orderly grid pattern that may span the water for as far as you can see or simply form near the shallow waters of the beach, what you are observing is not the product of something below, but rather two weather systems colliding. This is due to the nature of what you are seeing. Violent riptides are ready to pluck even the strongest swimmers from surface safety to the depths below, and not only this, but ships have even been tossed about when encountering these wave systems. Square waves are also called a ‘cross sea’… and for a good reasonĪ cross-sea is exactly as it sounds. So, what causes them, and just how dangerous are they? Let’s explore this anomaly so that you can get a better idea of why it’s a good idea to stay away from the water if you spot dangerous cross waves. Square waves are beautiful, amazing, and potentially deadly. Square waves in the ocean are a phenomenon that you may observe on the Isle de Ré in France and in some parts of New Zealand.
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