From the University of Hawaii at Manoa, more of the “more heat = more hurricanes” meme.
Threshold sea surface temperature for hurricanes and tropical thunderstorms is rising
IMAGE: The average tropical sea surface temperature (black) and an estimate of the sea surface temperature threshold for convection (blue) have risen in tandem over the past 30 years.
Scientists have long known that atmospheric convection in the form of hurricanes and tropical ocean thunderstorms tends to occur when sea surface temperature rises above a threshold. The critical question is, how do rising ocean temperatures with global warming affect this threshold? If the threshold does not rise, it could mean more frequent hurricanes.
According to a new study by researchers at the International Pacific Research Center (IPRC) of the University of Hawaii at Manoa (UHM), this threshold sea surface temperature for convection is rising under global warming at the same rate as that of the tropical oceans. Their paper appears in the Advance Online Publications of Nature Geoscience.
In order to detect the annual changes in the threshold sea surface temperature, Nat Johnson, a postdoctoral fellow at IPRC, and Shang-Ping Xie, a professor of meteorology at IPRC and UHM, analyzed satellite estimates of tropical ocean rainfall spanning 30 years. They find that changes in the threshold temperature for convection closely follow the changes in average tropical sea surface temperature, which have both been rising approximately 0.1°C per decade.
“The correspondence between the two time series is rather remarkable,” says lead author Johnson. “The convective threshold and average sea surface temperatures are so closely linked because of their relation with temperatures in the atmosphere extending several miles above the surface.”
The change in tropical upper atmospheric temperatures has been a controversial topic in recent years because of discrepancies between reported temperature trends from instruments and the expected trends under global warming according to global climate models. The measurements from instruments have shown less warming than expected in the upper atmosphere. The findings of Johnson and Xie, however, provide strong support that the tropical atmosphere is warming at a rate that is consistent with climate model simulations.
“This study is an exciting example of how applying our knowledge of physical processes in the tropical atmosphere can give us important information when direct measurements may have failed us,” Johnson notes.
Caption: Tropical ocean thunderstorms tend to occur above a threshold sea surface temperature.
Credit: Image courtesy NASA Image Science & Analysis Laboratory
The study notes further that global climate models project that the sea surface temperature threshold for convection will continue to rise in tandem with the tropical average sea surface temperature. If true, hurricanes and other forms of tropical convection will require warmer ocean surfaces for initiation over the next century.
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This work was supported by grants from NOAA, NSF, NASA, and JAMSTEC.
Captions: Figure 1. Tropical ocean thunderstorms tend to occur above a threshold sea surface temperature. Image courtesy NASA Image Science & Analysis Laboratory
Figure 2. The average tropical sea surface temperature (black) and an estimate of the sea surface temperature threshold for convection (blue) have risen in tandem over the past 30 years.
Citation: N.C. Johnson and S.-P. Xie, 2010: Changes in the sea surface temperature threshold for tropical convection. Nature Geoscience, doi:10.1038/ngeo1004.
@cohenite
“Yes, that is a persistent thorn for AGW: the ‘failure’ of direct measurements.”
Really, beautifully put. This weeks prize for the most contextual information conveyed via inverted commas.
Richard111 @12:57 am
Were these 100 mph winds gusts or sustained? It matters because the Saffir-Simpson scale is not concerned with gusts.
“Sustained winds is defined as:
http://www.nhc.noaa.gov/sshws.shtml
Why so few hurricanes? Too much threshold?
So, it’s worse than we thought?
So is it not as bad as they thought?
How much of the current hyperbole in AGW coming from “scientists” is coming from the uber-exuberance of graduate students, post-docs, and the newly graduated? To be sure, there’ll be a faculty advisor tagging along on the paper, since its his $$ (well, not his, really) funding the study, but that’s just the business of science. I’m suspecting we’re seeing more social conditioning than actual science. Most of these kids haven’t passed enough water yet to get the big picture…
Though this NASA funded study goes back further than 30 years it does actually show what has been OBSERVED.
and here’s hurricane intensity.
Do these climate scientists teach their pet dogs to perform tricks like the they teach their models to perform tricks? Do their pet dogs have anthropomorphic names? Do they have pet dogs…or parrots?
So if actual data doesn’t match expected results, go with the expected results and congratulate yourself.
Uh-huh. Let’s see how the CFO of where I work likes that idea.
Scarlet Pumpernickel says:
So why did cyclone Tracey destroy Darwin in 1974 and nothing has happened since?
Didn’t you get the memo? Cyclone Tracy didn’t happen. It was the same sort of problem that led people to believe in things such as the MWP and LIA. Don’t worry, though. The scientists have fixed everything up.
One day, they’ll eliminate every piece of real data from the records…
Another question, how does looking at 30 years of stellite records give rainfall totals?
Convective precipitation falls over a certain area for a relatively short time, as convective clouds have limited horizontal extent. Just to know the percipitation for one day one would have to anaylize 24 hours of satelite information. Correct me if this is not a valid concern.
Put the blame on Meme, boys, put the blame on Meme!
I worked with a Behavioural Psychologist years ago who trained his pet house cat to ‘go’ in the toilet rather than use a sand tray, but he could not, no matter how long he worked with the cat or whatever reward system he used, the cat just would not attempt to flush the toilet. The reason… he suspected the cat had very quickly worked out it was physically way too light to actuate the mechanism, but could never prove it, as the cat refused to talk to him.
Ain’t science wonderful!
I’ll tell you a threshold that is not rising, and that’s the one for dissent on the “Open Mind” blog. In response to his article about likelihood of Arctic melt being due to AGW, I simply replied: “You don’t mention the Antarctic once, I wonder why?”.
Of course it was rejected. Never mind, now far more people will read it on this blog. Thanks Anthony!
Somewhat on topic, I posted the October 2010 Reynolds OI.v2 SST anomaly data yesterday:
http://bobtisdale.blogspot.com/2010/11/october-2010-sst-anomaly-update.html
The findings of Johnson and Xie, however, provide strong support that the tropical atmosphere is warming at a rate that is consistent with climate model simulations.
Then….will they adjust Argo buoys to forcefully agree with their models?
That curve stops at 2005…….hmmmm. Gotto read WUWT: Here they will know that there is something very interesting happening, not considered in their models.
Try Weee instead, at least it will make you relax.
graham g says: “The worst period for cyclones in the southern hemisphere around the Australian coastline in the past century was about 40 to 60 years ago. Why does this graph showing increased SST temperatures start at 1980, given reliable data from shipping records goes back to the 1900 period.?”
Not in the Southern Hemisphere. The vast majority of Southern Hemisphere (and tropical Pacific) SST data prior to the satellite era (and the TAO buoy era for the tropical Pacific) is infilled data, a.k.a. make-believe data.
Real causation knowledge lacking.
Storms are driven by differences in temperature. Venus is universally hot and has no storms.
A warming Arctic means fewer storms.
Juraj V. says: “If I understood it well, the models find the tropospheric hot spot while direct measurement do not.”
The tropospheric hotspot exists…whenever there is an El Nino event. Then, there’s a great big warm plume from the convection coming from the tropical Pacific.
The models show amplified warming in the tropical troposphere, while these results suggest parallel rates of warming… that is, no amplification of surface warming; which is what skeptics have been saying all along. How this gets spun into a ‘confirmation’ of modeled amplification is far from clear from the press release, but ‘spun’ seems the operative word. But without spending a bunch of money to get the article, there is no way to know for sure what the authors really say.
Press releases for journal articles that are only available behind pay-walls should be a misdemeanor, punishable by up to 3 months in prison.
How does a tornado or hurricane get it’s wind energy?
Magic Wand?
Have yet to see a tornado generated from the ground up.
Wow, no error in their measurements and no uncertainty in their conclusions. They sound like the guys on TV hawking gold and stain removers.
Did you notice that in the image description, the blue line is “an ESTIMATE of the sea surface temperature threshold for convection (blue)”. So because their ESTIMATE of a threshold temperature correlates with the SST, they can overlook measured data that contradicts their theory.
Just how much “science” was involved in their “ESTIMATE“? OK, if they did use science it was a SWAG, otherwise it was just a WAG constructed to explain away real measurements.
The fact remains that ACE is at 30 year lows in spite of the fact that CO2 continues to go up, up, and away! Too bad, so sad for the warmers that the mid-tropospheric temperatures have not gone up, up, and away in my beautiful, my beautiful balloon!
Richard111 says:
November 9, 2010 at 12:57 am
Hmm, perhaps we need to run a post in honor of the first hurricane of each season that describes tropical storms and how they differ from extratropical storms.
The most striking feature of a tropical storm is that the center is surprisingly clear, calm, and warm. This eye structure come from winds in the eyewall so strong the core can’t pull them in closer. Instead, convection in the eyewall releases “latent heat” as rain forms, and at the top of the storm some of the dried air sinks in the core and its temperature rises as it returns to sealevel.
This sort of storm can’t be maintained outside of the tropics. Extratropical storms are fueled by the temperature differences of cold air to the north, and warm, moist air to the south. That’s forced over the cold air releasing rain and energy. While they may sport an “eye-like structure” briefly, the core of the storm is normally the same as the surrounding cold air.
They also are a focal point for warm and cold fronts, reflecting the air masses involved, and have a wider wind field than hurricanes That’s one reason extratopical storms are not tracked as precisely as tropical storms. Tropical storms that move north almost always change to extratropical storms, and the US National Hurricane Center stops following them.
So, even though you experienced hurricane force winds, you almost certainly had an extratropical storm and not a hurricane. On this side of the puddle, we have pet names for them, e.g. Nor’easters off the new England coast and the Witch of November around Lake Superior in the north central US. I hope to have a lot more to say about the latter tomorrow.
Clearly your area needs a pet name for its storms. Guv’nor Blowhard perhaps? Flatrain (since the rain is nearly horizontal in 100 mph wind)? Royal Rain? I hope you can do better than those!
“This study is an exciting example of how applying our knowledge of physical processes in the tropical atmosphere can give us important information when direct measurements may have failed us,” Johnson notes.
So another example of how poor we measure our climate? OR, observation bias?
“…Nat Johnson, a postdoctoral fellow at IPRC, and Shang-Ping Xie, a professor of meteorology at IPRC and UHM, analyzed satellite estimates of tropical ocean rainfall spanning 30 years.”
Which ever way you look at it, the science isn’t good!