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Off-Topic >> Everything and Nothing


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Quikscat Failure - What am I Missing ??
      Mon Jun 25 2007 12:11 AM Attachment (322 downloads)

I have a few questions regarding the 'imminent failure' of the QuikScat satellite.

Perhaps some of the many capable meteorologists and other 'technical experts' that contribute to these excellent forums could provide feedback and address my questions.

First, a few quotes pertaining to the QuikScat satellite, excerpted from various news articles and postings.

>> The National Oceanic and Atmospheric Administration's chief said the failure of the QuikScat satellite could bring more uncertainty to forecasts and widen the areas that are placed under hurricane watches and warnings.

>> If the satellite faltered, experts estimate that the accuracy of two- day forecasts would suffer by 10 percent and three-day forecasts by 16 percent, which could translate into miles of coastline and the difference between a city being evacuated or not."

>> Bill Proenza, director of the National Hurricane Center in Miami, said authorities "may have to err on the side of caution in future forecasts. That means more people disrupted, and more impact on the economy. On the other hand, we have to err on the side of the protection of life. And that's how we would handle it."

CNN picked up on this article after it came out (perhaps many of you saw it) and, using Katrina as an example while Katrina was still in the GOM several days away from making landfall, showed how the 'cone of uncertainty' would have to be widened by 100 miles or so *on each side* of its projected landfall..

>> In the letter to a Florida congressman, NOAA Administrator Conrad Lautenbacher blamed the delays on technical and budget problems. Scientists said if QuikScat failed, they may have to rely on less accurate satellites.

OK. Enough quotes for the moment. Now for a few thoughts and questions.

I consider myself a veteran storm tracker, having been tracking them since the very first male named hurricane, David, back in '79 when I lived in Coconut Grove. And I'm quite familiar with the various satellites, their sensor packages, their capabilities, and so forth.

I also make extensive use of the NRL (FNMOC) Tropical Cyclone homepage, and the many, excellent products available on the site, including the QuikScat products.

First question: Are the other satellites really 'less accurate' ?

I thought that the GOES satellites, with their '1 Km Zoomed' images, especially for cyclones with well-defined eyes, are *very* accurate for providing 'center fixes' in the absence of aircraft recon or land-based NEXRAD images, as is typical when these storms are still 'at sea', far from any land areas.

And, during nighttime hours, the Microwave sensors of several different satellites also show, quite well, the center positions for storms that are far from land, well before the hurricane hunters are sent out on recon missions to obtain detailed information.


Now for a few thoughts on the QuikScat satellite itself.

>> "When you look at QuikScat, what it does is it gives us a swath of data that's 1,500 to 1,800 kilometers wide, all at one time, one moment. It covers 90 percent of the global oceans in one day,"

>> If the satellite fails, the options are few. Other satellites have instruments to measure wind speed and direction over water, but they are less accurate.

Now, my understanding (and correct me if I'm wrong) is that QuikScat is a truly valuable tool for monitoring areas of disturbed weather ('Invests') and provides excellent (if not timely) data during cyclogenesis into Depression and Tropical Storm status.

I've always been very interested in studying the illustrative, color-coded wind barbs, showing the thunderstorms organizing while the cyclone is in the intensification stage, usually depicting the strongest wind barbs in the 'rain-contaminated' convective areas.

With me so far? But the 'wind scale', as shown on the bottom of the image, only goes up to 60 Kts. (orange barbs), and it seems that QuikScat cannot measure hurricane force winds (65 Kts. +).

But it is still obviously valuable in showing the 'center of circulation' (but less accurately than the GOES 1 Km zoomed images?), and, perhaps more importantly, the radius (usually asymmetric) of Tropical Storm force winds accompanying maturing or fully matured hurricanes.

I am including an attachment (please click the 'Attachment' link at the top of this post to view) of powerful GONU in the Arabian Sea on June 5th, while it was a 105 Kt (Cat 3) cyclone. You'll notice that the strongest depicted wind barb is QuikScat's 60 Kt 'limit'; a *single*, orange barb near the center of GONU. Should there not be many more orange barbs near the center? And this is also the 'closest' QuikScat image to it's maximum intensity as a Cat 5 cyclone.

And here's a few, final thoughts about the QuikScat instrument, before I come to the point of this post, in relation to the larger context of the News articles posted above. Please bear with me. You will see where I am going with this.

It's been my experience, over many years of observing, that there is sometimes *many hours* duration (sometimes a day or more!) between the times that QuikScat will make a 'direct pass' over any given storm. And often, it's an 'incomplete' scan, where the sensors' path 'samples' only a partial portion of the complete circulation (as with the GONU image attached), and sometimes completely missing the 'eye' of a mature hurricane altogether.

And finally, it sometimes seems that the 'center of circulation' does not correlate too well with the overlaid visible image, as is the case, again, with the GONU image provided. Note that there is only a 16 minute difference between the QuikScat and the Visible images, not nearly enough time duration to account for the 'apparent discrepancy'.

OK. Let's sum up before I make my point and venture a few questions.

1) QuikScat shows only tropical storm force winds; only up to 60 Kts.
2) There is often *many* hours elapsed between passes over any given storm.
3) The scan is often 'incomplete', depicting only a portion of the entire circulation.
4) Sometimes, the scan will miss the center of circulation entirely.
5) Sometimes, there appears to be poor correlation between the QuickScat image and the overlaid Visible or IR image, even when the time difference is not that large.

Hope I haven't put too many of you to sleep, because here comes the good part ...

When we have a Hurricane or Tropical Storm threaten a coastal area of the US, we send out the 'Hurricane Hunters' to fly into the storm 'round the clock, providing very accurate center fixes, sampling it's radius of TS-force winds, and providing a plethora of very detailed thermodynamic data to the NHC, and other agencies, for use in initializing the various numerical models that ultimately go into the forecasted watches and warnings.

And sometimes we send up the high-flying NOAA aircraft to provide detailed info of upper-level steering currents, etc., again, all very helpful as additional data to 'plug into' the models and other forecasting tools.

OK. Now my point(s) and a few questions. Let's take Katrina as an example, since it's the example that CNN used for their segment, which was seen by millions of viewers.

>> QuikScat ... provides key data on wind speed and direction over the ocean. Weather aircraft and buoys can also obtain similar measurements near a storm, but they do not provide a constant flow of data as QuikScat does.

Hmmm... I respectfully disagree. QuikScat does *NOT* provide a "constant stream of data" (for any given storm), as I discussed in the above paragraphs.

In view of the *truly* constant stream of data provided by the continuous recon missions into Katrina while she was still in the Gulf, did the QuikScat data *really* provide that much useful data, in comparison to the *huge volume* of data provided by the buoys and recon missions themselves?

If the QuikScat had *completely* failed, say, a week before Katrina formed, would the NHC *really* have had to widen the 'cone of uncertainty' by a hundred miles on each side of the projected landfall? With all the excellent recon data, I think not.

>> "We would go blind. It would be significantly hazardous," said Wayne Sallade, emergency manager in Charlotte County, which was hit hard by Hurricane Charley in 2004.

I just don't understand this statement, at all. Any storm in the GOM, hurricane or otherwise, threatening the west coast of Florida, would certainly have non-stop recon missions (or at least 6 hourly 'fixes') flown into it. Would the absence of QuikScat really render us 'blind' ??

>> If the satellite faltered, experts estimate that the accuracy of two- day forecasts would suffer by 10 percent and three-day forecasts by 16 percent, which could translate into miles of coastline and the difference between a city being evacuated or not. " ... we have to err on the side of the protection of life ... that's how we would handle it."

Again, any 'significant' storm, even 2 or 3 days away from a projected landfall on a US coastline, would have plenty of satellite imagery (GOES, primarily) and aircraft reconnaissance data providing excellent center fixes and intensity information, among other data, to assist in the initialization of the numerical models. Would the lack of QuikScat really make *that much* of a difference, in view of its inherent limitations, as discussed above?

Now to wrap up. I'm not trying to undermine or underestimate the importance of the QuickScat satellite. It's a great tool, and I'm fascinated by the detailed 'picture' (albeit not timely) of the cyclogenesis process it provides as the storm progresses from an Invest into a named storm.

But I still contend that its importance, with respect to potentially US landfalling hurricanes, is marginalized by the superb recon we receive from the hurricane hunters, especially, once they begin their non-stop missions.

And finally, to reiterate. QuickScat is great for 'Invests' and TD and TS strength cyclones, especially in the data-sparse regions over huge oceanic areas. And in showing the radius of TS-force winds of matured storms, as well.

But once we have a potentially landfalling hurricane 2 or 3 days from a US landfall and the 'data-rich' recon missions begin, I feel that QuickScat's 'overall contribution' for forecasting landfall is truly marginalized and, in it's complete absence as would occur with a total satellite failure, should *NOT* contribute to widing the area of US coastline for which watches and warnings are issued, which is the focus of the News articles.

What am I missing ?? Your thoughts and feedback would be appreciated.

"Don't Get Stuck on Stupid" - General Honore, following Hurricane Katrina

Post Extras Print Post   Remind Me!     Notify Moderator

Entire topic
Subject Posted by Posted on
* QuickSat to fail ANYTIME HCW Mon Jun 25 2007 12:11 AM
. * * Quikscat Satellite danielwAdministrator   Tue Jun 12 2007 11:49 PM
. * * Quikscat Failure - What am I Missing ?? CoconutCandy   Mon Jun 25 2007 12:11 AM
. * * Re: Quikscat Failure - What am I Missing ?? Robert   Tue Jun 26 2007 01:34 AM
. * * What am I Missing? / Katrina QuikScat Image CoconutCandy   Tue Jun 26 2007 04:14 AM
. * * Re: What am I Missing? / Katrina QuikScat Image Ricreig   Tue Jun 26 2007 08:41 AM
. * * New Understanding / Remaining Issues CoconutCandy   Wed Jun 27 2007 01:09 AM
. * * Re: New Understanding / Remaining Issues Ricreig   Wed Jun 27 2007 01:40 AM
. * * Finally Satisfied / Photo of Florida from the Space Shuttle CoconutCandy   Wed Jun 27 2007 02:26 AM
. * * Re: Finally Satisfied / Photo of Florida from the Space Shuttle madmumbler   Mon Jul 02 2007 10:34 AM
. * * Re: What am I Missing? / Katrina QuikScat Image Robert   Tue Jun 26 2007 08:28 AM
. * * Re: Quikscat Satellite LoisCane   Wed Jun 13 2007 03:11 PM
. * * Re: Barry Gone, Quiet Again josh   Tue Jun 12 2007 06:02 PM

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