NASA's Hurricane Model Resolution Increases Nearly 10-Fold Since Katrina

zdburke writes: Thanks to improvements in satellites and on-the-ground computing power, NASA's ability to model hurricane data has come a long way in the ten years since Katrina devastated New Orleans. Their blog notes, "Today's models have up to ten times the resolution than those during Hurricane Katrina and allow for a more accurate look inside the hurricane. Imagine going from video game figures made of large chunky blocks to detailed human characters that visibly show beads of sweat on their forehead." Gizmodo covered the post too and added some technical details, noting that, "the supercomputer has more than 45,000 processor cores and runs at 1.995 petfalops."

Comments

Hey, that's great!

[Anonymous Coward]

A much more accurate look at that thing we can't predict the path or intensity of!

Re:Hey, that's great!

[hey!]

Actually we can predict pretty damn well. It depends on what you compare to: perfection, or what we could predict thirty years ago, or seventy-five years ago.

We're living in an era of rapid improvements in weather forecasting in terms of accuracy, precision and scope. Back in the 70s there was a perennial science fair project in which the student compared the accuracy of tomorrow's weather forecast to simply assuming that tomorrow would be like today. The answer back then was, it was about equally accurate. Today would be a totally different story. The forecasts we get for three days out is better than the forecast we used to get for tomorrow back in the 70s; people just haven't updated their thinking.

It's not surprising when you realize that the difference is satellite tracking, meteorological data networks, and incomprehensibly more powerful computers. Today's smart phones are roughly as powerful as the supercomputers of the 1980s.

Re:Hey, that's great!

[Rainbow Nerds]

I'm going to agree with the AC above me and say yes, increasing the resolution will generally result in a better forecast. There are two areas that generally can improve weather models: better initial conditions for the model and higher resolution.

Hurricane tracks are primarily influenced by large areas of high and low pressure and the accompanying upper-level winds. Even a coarse model with grid points every 50 km will probably produce a reasonably accurate representation of large features. Adding to the resolution might help a bit, but it's not likely to improve the forecasting of hurricane tracks that much.

Hurricane intensity, however, is driven by the storms in the inner core of the hurricane. They typically form a ring around the eye of the storm and are referred to as the eyewall. They're basically thunderstorms but without a lot of lightning, typically less than 10 flashes per hour. Inside those storms, large amounts of water vapor condense, and when this happens, latent heat is released. The latent heat comes from the energy that's no longer being used to keep the molecules of water apart once the state changes from gas to liquid. This heat warms the air, causing the column of air to expand upward. When this happens, you get high pressure at the top of the hurricane, and air spirals out from there. Air is flowing out of the core of the storm at the upper levels, so there's less air to press down on the surface. This causes the surface pressure to fall and the hurricane intensifies. These storms are small, on the order of 20 km across, but they're really important to predicting hurricane intensity. If the model has its grid points spaced 50 km apart, you may not have any grid points to resolve the storms. One of the newer hurricane models, the HWRF, now goes down to a grid point spacing of 2 km. There are a lot more grid points from which to represent the storms in the inner core of the hurricane. That allows much better prediction of hurricane intensity.

For a few decades, hurricane track forecasting had improved quite a bit as the global models could better predict the high and low pressure systems that drive hurricane tracks. During a lot of that time, predictions of hurricane intensity didn't get a lot better. Only within the past decade or so have we seen bigger improvements in forecasting hurricane intensity. That's largely a result of more computing power and models that are able to directly simulate what's going on in the inner core of the hurricane.

I do agree with the AC that it's not as simple as changing a couple of numbers in a configuration file to get a higher resolution and automatically getting a better forecast. There is something of an art to modeling. Even with a really high resolution grid, there are still processes that can't directly be simulated or are on a smaller scale than the grid. We still have to parameterize those. But improving the resolution is generally a good thing.

Re:Yes, you've increased the precision

[cusco]

building a home that can handle the winds from a Category 1 storm isn't that hard.

It is when the primary criteria is "build it as cheaply as we can get away with and not have to bribe the building inspector". It's embarrassing the crap being slapped together today, especially to a former remodeler. When you step into a multi-million dollar house and notice that the counter tops aren't even level, the floor trim and cove molding rely on caulk and plastic wood to come together, and the ceiling is so wavy that the chandelier base plate doesn't even touch in places you know damn well that there aren't hurricane braces on the roof joists and the wall framing isn't anchored to the floor joists.

Re:Well, nice but that was not the problem...

[cusco]

The poor couldn't leave, because free/cheap transportation wasn't available except in a few situations (church buses and the like). ( And if you're poor in Louisiana you're about as poor as you can get in the US.) Even many of the nursing homes weren't evacuated unless they were able to afford to arrange specialty transportation.

Yeah, it would have been nice if more people had evacuated, but after a series of free market fanatics running the state government there just wasn't the capacity.