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Replacement For Aging Doppler Radar Being Tested
longacre writes "Due to its limited range and slow scan times, the backbone of weather prediction in the US since the early 1990s, the NEXRAD radar system, is deeply flawed in the eyes of meteorologists. A new system being tested by researchers at the NOAA and four universities called the Collaborative Adaptive Sensing of the Atmosphere (CASA) network aims to fill the holes left by NEXRAD, using radar nodes piggybacked onto existing infrastructure, such as rooftops and cell towers. From the article: 'Based on faster and more comprehensive data collection, [Distributed Collaborative Adaptive Sensing] processing can refocus the CASA radars on a particularly interesting part of a storm (like an area that looks like it might develop a tornado) without losing track of an entire storm cell. "The system is continuously diagnosing the atmosphere and reallocating resources using wireless Internet as a backbone," says [the CASA team director].' Testing has begun in Oklahoma, Houston, and Puerto Rico, and initial installations could begin in 5 years."
From the article...
No, not so much. The National Weather Service has started issuing storm-based (polygon-area based) warnings since August 2007. Prior to that, they were county-based warnings, which were a problem (Cook County, IL being about 50 miles tall by 40 miles wide, while average tornado widths are about 100 yards) but nowhere near the "statewide warning" the article claims.
Awful FAQ here: http://www.nws.noaa.gov/sbwarnings/FAQ/engage.html
-Rob
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It's still property, it's still their home.
And they still lost it.
I think we'll see what's going on now with more fidelity, but weather prediction is still limited by chaos. Weather is sensitive to initial starting conditions, so no matter how well we know those starting conditions (today's weather), we will not be able to predict future weather more than about 10 days out with any kind of fidelity. We've also noticed that some weather patterns are more chaotic than others. You may notice sometimes they say stuff like, "The hurricane will make landfall tomorrow morning at 2am here." And sometimes they say, "We really don't know what this storm is going to do. It could land tonight or blow north. We'll have to see." What they do is run several simulations using variables a few decimal places off. Sometimes they all do the same thing, sometimes they vary so much there's no way to know what's going to happen. Adding new radar will not change the fact that weather is inherently chaotic and unpredictable.
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
The radars take several scans of the sky per "update".
.5 degrees of dish elevation, 1.45 degrees, 2.4 degrees and 3.35 degrees. Those scans dissect the storm and look for rotation and intensity in different parts of the storm.
They take scans at
Then the radars take an "echo tops" scan where the dish moves up and down to its limits while scanning horizontal. That lets the radars detect the total height of a storm, which gives another estimate of its strength.
So, its not just the dish spinning around in a single plane.
The summary statement gets things wrong in pretty much every respect, so this is mainly for those folks who read the summary and assume it's a fair reflection of the story.
(1) CASA is not designed to replace the existing NEXRAD network. It is designed to supplement it. NEXRADs are designed for long-range surveillance. CASA radars see "under" the NEXRAD umbrella, up to 3km in height. The article makes this clear.
(2) NEXRAD scans are not slow. The fastest volume coverage patterns (VCPs) in NEXRAD, used in severe weather, scan the atmosphere every 4 minutes. The only thing faster is phased array radar and it is still experimental (See: http://www.oar.noaa.gov/spotlite/). CASA radars don't have volume scans, but their antennas are about the same speed as NEXRAD's.
(3) NEXRAD is not limited in range. It goes up to 460 km. A CASA radar's range is only 30 km. If any one thinks that NEXRAD is "deeply flawed" due to its limited range, they need to take it up with the Flat Earth Society (the range limitation is mostly because of the earth's curvature).
Please make sure you understand an article before sending it off to Slashdot!