Stronger SST-intense hurricane link?

By: Dr. Jeff Masters , 2:53 PM GMT on April 12, 2006

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A link between global warming and increased intense hurricane activity is a very hot topic in hurricane research right now, and many new papers on the subject will be published this year. The latest paper, published March 15 in the on-line version of Science, Science Express, finds stronger evidence that the increasing number of Category 4 and 5 hurricanes globally since 1970 is directly linked to increases in Sea Surface Temperature (SST). The paper by Hoyos et al. was called, "Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity". Two of the co-authors--Peter Webster and Judith Curry of Georgia Tech--were also authors of a paper published in Science magazine in 2005 that reported a worldwide increase in the number of Category 4 and 5 hurricanes of 80% in the past 30 years. The paper, (Webster et al., 2005), titled "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment", linked the rise in storms to increasing sea surface temperatures and concluded that "global data indicate a 30-year trend toward more frequent and intense hurricanes." As I reported in my blog on the subject, their findings should be considered as preliminary evidence that the global incidence of Category 4 and 5 hurricanes may be increasing. There are some severe problems with the quality of the data set used to, and there are good reasons to believe that the actual increase in Category 4 and 5 hurricanes is far lower than the 80% increase found by Webster et al.

The new paper by Hoyos et al. uses a mathematical technique called information theory to study the relative effects of SST, wind shear, humidity, and wind patterns on global incidence of Category 4 and 5 hurricanes. The study found that only SST can explain the observed increase in these storms. One thing I like about the new study is that it directly addesses the issue of data quality in the record of Category 4 and 5 hurricanes, something the authors neglected to do in their previous paper. The authors write, "Recently, the quality of the hurricane data has been questioned and even a reanalysis of the tropical cyclone databses has been suggested in order to ratify that the results of recent studies are not due to problems in the data." The authors go on to say that they performed their analysis without using suspect data from the North Indian Ocean, and found no difference in their results. Well, that's not too surprising, since the number of Category 4 and 5 hurricanes in that ocean basin represents only about 2% of the global total. What I would have liked to have seen was the analysis re-done using the latest reanalyzed results for typhoons from the Western Pacific, which accounts for 48% of global Category 4 and 5 hurricanes. In a paper accepted for publication but not yet finalized, Knaff and Zehr (2006) make convincing arguments that typhoon intensities during the 1973-1986 period were too low due to measurement error, and the number of Category 4 and 5 storms in the region have been roughly constant for the past 50 years. Dr. Knaff and Charles Sampson have performed a preliminary re-analysis of maximum typhoon intensities for the period 1966-1987 based on the Knaff and Zehr (2006) results. In a paper to be presented at the upcoming 27th Conference on Hurricanes and Tropical Meteorology (April 24-28, 2006), they show that after correcting for the measurement errors, the number of Category 4 and 5 typhoons during the 1966-1987 period increased by 1.5 per year, leaving only a slight upward trend in Category 4 and 5 typhoons during the period 1970 - 2004. The 16% increase in Category 4 and 5 typhoons found by Webster et al. during the past 15-year period is reduced to just 3%. I suspect that if the information theory techniques of Hoyos et al. were applied to this modified data set, the connection between SST and an increase in global Category 4 and 5 hurricanes would be much weaker.

The realclimate.org blog has more information on the paper, along with links to quotes in the media from many of the scientists involved in the hurricanes/global warming debate.

My next blog will be on Friday. Apparently, NHC has "found" a new Atlantic subtropical storm that formed in 2005, bringing the total for the season to 28 named storms. If the final report on this new storm has been issued, I'll discuss that.

Jeff Masters

references
Hoyos, C.D., P.A. Agudelo, P.J. Webster, and J.A. Curry, "Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity", www.scienceexpress.org, 16 March 2006, 10.1126/science.1123560.

Knaff, J.A., and R.M. Zehr, "Reexamination of Tropical Cyclone Wind-Pressure Relationships", accepted to Weather and Forecasting, 2006.

Webster, P.J., G.J. Holland, J.A. Curry, and H.-R. Chang, "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment", Science, 309, 1844,1846, 16 September 2005.

Alpha Chi Omega missing a wall (Arian)
The twister tore a whole wall from the sorority house and detroyed everything around it.
Alpha Chi Omega missing a wall

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106. ProgressivePulse
12:33 AM GMT on April 13, 2006
I tell ya what, the soon to be CUL is trying, I think I can, I think I can. Please return all drool tables to thier full upright and locked positions until June, shear levels and the large drape approacing aught to knock it out.
Member Since: August 19, 2005 Posts: 5 Comments: 5451
105. Inyo
12:43 AM GMT on April 13, 2006
oops, that above should read 'if they sell less oil they make less money'
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104. Inyo
12:27 AM GMT on April 13, 2006
I think the root of this political issue is this:

Oil companies sell oil, if they sell less oil they make more money. Therefore, it is in the interest of the oil companies to support research that denies global warming as a factor. Of course to some extent this is fair, if an unfair accusation is being made about oil's effects we should find out. However, it seems that there are a lot more people who profit from the con argument (oil companies and politicians) than the pro warming argument (only politicians, maybe?). I never really understood who is profiting from the 'pinko liberal' greenhouse warming argument... who makes money off of the belief that we are warming the climate? biodiesel manufacturers? Maybe since i am a liberal i can't see the liberal bias, but i don't believe it exists.

anyway, sorry to get political...

i'm waiting on a big (non tropical) low to pass over us on Friday.. it may be the last spring storm of the year for so-cal so i'll enjoy it while i can
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102. DAVIDKRZW
12:21 AM GMT on April 13, 2006
and ts as well
101. Levi32
4:16 PM AKDT on April 12, 2006
Oops forgot the link
Member Since: November 24, 2005 Posts: 635 Comments: 26661
100. Levi32
4:14 PM AKDT on April 12, 2006
My gosh this thing could really go!!! Look at the floater loop! Here's the deal. The pocket of low shear east of Florida is going to expand and this disturbance will move into it. This will happen tonight. This thing may have a chance once it is cut off from the trough!!! The models seem to be forecasting it to move into the caribbean and move southward. This could be a TD in the making!
Member Since: November 24, 2005 Posts: 635 Comments: 26661
99. ForecasterColby
12:15 AM GMT on April 13, 2006
One usually can't see that until the storm is well-developed. It may be there, but it won't show up on imagery.

I posted an image of STS19 on my site.
98. Levi32
4:07 PM AKDT on April 12, 2006
thought
Member Since: November 24, 2005 Posts: 635 Comments: 26661
97. Levi32
4:05 PM AKDT on April 12, 2006
Yes but referring to cyclones, I though he might have ment clockwise as in the anticyclone over a tropical system.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
95. Levi32
4:00 PM AKDT on April 12, 2006
Globalize in your last post did you mean the first clockwise flow or was that correct?
Member Since: November 24, 2005 Posts: 635 Comments: 26661
94. Levi32
4:00 PM AKDT on April 12, 2006
Globalize in your last post did you mean the first clockwise flow or was that correct?
Member Since: November 24, 2005 Posts: 635 Comments: 26661
93. globalize
11:43 PM GMT on April 12, 2006
It seems all that is necessary to know if there is even the slightest chance of tropical development is to look at the water vapor flow. For the last several weeks, it has only been west to east in a clockwise flow.
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92. DAVIDKRZW
11:21 PM GMT on April 12, 2006
coool i give all the rain to FL


my blog is update by the way
91. globalize
11:18 PM GMT on April 12, 2006
Some of the first counterclockwise water vapor flow in nearly four weeks, SE of Miami.
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90. Zaphod
10:52 PM GMT on April 12, 2006
Boy, sometimes it's hard not to get agitated by the tone of some of the postings!

There is nothing wrong with spirited discourse on topics of public interest, including scientific ones. Regardless of the issue at hand, there will ALWAYS be conflicting views, spanning the gamut from willful propaganda and misinformation from those who profit directly to the more mundane math errors, human factors, and differing professional perspectives. Everybody has a bias, and each side ratchets up their volume to be heard above the din.

Why not study, debate, and theorize openly? Who cares if there is some misinformation by questionable sources? What difference does it make which side is right -- it's not like humanity has proven itself capable of acting for it's own good even if we KNEW what to do!

Are the global warming supporters upset because of the debate, or because they realize that it probably doesn't matter whether they're right or not? Easter Island indicates we humans ignore even the obvious, let alone the obscure.

Zaphod
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89. FLCrackerGirl
7:01 PM EDT on April 12, 2006
Ever get the feeling you're looking at a
Rorschach Inkblot Test with these sat images or models?? LOL.
Really Could Use the Rain (Albeit Less Wind).
Thanks All for Being Storm Watchdogs.
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88. HurricaneKing
10:59 PM GMT on April 12, 2006
That there is a chance there might be a low forming out of the ull.
Member Since: July 6, 2005 Posts: 71 Comments: 2485
87. DAVIDKRZW
10:56 PM GMT on April 12, 2006
so what dos that all mean
86. HurricaneKing
10:47 PM GMT on April 12, 2006
THE GULF OF MEXICO...THE NORTHWESTERN CARIBBEAN SEA...
AND THE ATLANTIC OCEAN WEST OF 50W...
THE RIDGE THAT STRETCHED FROM MEXICO TO TEXAS AND OKLAHOMA AND
BEYOND HAS SEEN ITS NORTH-TO-SOUTH ORIENTATION CHANGE TO MORE
OF SOUTHWEST-TO-NORTHEAST ANGLE. A DEEP LAYER TROUGH HAS SWEPT
ACROSS THE INTERIOR U.S.A. AND PUSHED THE NORTHERN EXTENSION
OF THIS RIDGE EASTWARD ALSO...FROM GEORGIA NORTHWARD ALONG THE
U.S.A. EAST COAST. THE SOUTHERN END OF THE WESTERN ATLANTIC
OCEAN-TO-SOUTHEASTERN GULF OF MEXICO TROUGH FROM 24 HOURS AGO
HAS BEEN PUSHED INTO THE NORTH CENTRAL CARIBBEAN SEA. IT IS
POSSIBLE THAT A CUT-OFF LOW CENTER MAY DEVELOP IN THE AREA OF
THE SOUTHERN BAHAMAS...WHERE THE GFS HAS BEEN MAKING A FORECAST
OF A SURFACE LOW.
THIN HIGH CLOUDS WITH THE RIDGE COVER THE
GULF WATERS WEST AND NORTHWEST OF 29N83W 24N89W 21N94W.
SHOWERS ARE POSSIBLE IN CONFLUENT LINES OF LOW CLOUDS...MOST
NOTABLY IN THE SOUTHWESTERN CORNER OF THE AREA...AND NORTH
OF 22N EAST OF 90W. A MIDDLE TO UPPER LEVEL LOW CENTER ON
WATER VAPOR IMAGERY IS IN THE AREA FROM 22N TO 23N BETWEEN 77W
AND 78W. A TROUGH EXTENDS FROM THIS LOW CENTER TOWARD EASTERN
HONDURAS.
SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ARE FOUND FROM 23N TO 27N BETWEEN 68W AND 77W.
CYCLONIC FLOW AROUND THIS COMBINED FEATURE COVERS THE ATLANTIC
WATERS NORTH OF 20N WEST OF 68W...AND IN THE CARIBBEAN SEA NORTH
OF 15N BETWEEN 74W AND 90W. AN UPPER LEVEL RIDGE IS IMMEDIATELY
EAST OF THIS TROUGH/LOW CENTER. OVERCAST MULTILAYERED CLOUDS
AND SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS
ARE WITHIN 180 NM ON EITHER SIDE OF 27N67W BEYOND 32N59W.
A STATIONARY FRONT RUNS FROM THE 1013 MB LOW PRESSURE CENTER
NEAR 22N73W TO 26N70W TO 30N64W AND BEYOND 32N60W.
A SURFACE
TROUGH RUNS FROM 17N70W TO 24N67W. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND POSSIBLE SHOWERS ARE FOUND NORTH OF
15N BETWEEN 65W AND 74W IN THE CARIBBEAN SEA.
Member Since: July 6, 2005 Posts: 71 Comments: 2485
85. HurricaneMyles
10:36 PM GMT on April 12, 2006
Doesn't look very impressive that's for sure. Definetly no threat to become a dangerous hurricane. I say bring it on and give S. Fl some rain!
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84. turtlehurricane
10:26 PM GMT on April 12, 2006
considering the dry air, shear and approaching front, not to mention there is no surface low, this is not a threat to the U.S.
Member Since: July 22, 2005 Posts: 227 Comments: 469
83. louastu
6:31 PM EDT on April 12, 2006
Good that one works. I was getting really annoyed.
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82. louastu
6:29 PM EDT on April 12, 2006
http://wwwghcc.msfc.nasa.gov/GOES/goeseastconuswv.html

Ok........ This is the site.
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81. louastu
6:27 PM EDT on April 12, 2006
Oh well this is the website.

http://wwwghcc.msfc.nasa.gov/cgi-bin/post-goes
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80. louastu
6:26 PM EDT on April 12, 2006
Hmm.... Well, that didn't work.
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79. louastu
6:24 PM EDT on April 12, 2006
That system in the Bahamas looks pretty good on water vapor imagery.

Link
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77. indigenous
10:14 PM GMT on April 12, 2006
Question for someone: Why do landfalling hurricane intensity forecasts bust so frequently? i.e why don't they verify?
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73. turtlehurricane
10:02 PM GMT on April 12, 2006
http://virga.sfsu.edu/pub/jetstream/jetsat_atl/small/0510/05100406_jetsat_atl_small.gif



19 at peak intensity. 2005 lives beyond the grave!
Member Since: July 22, 2005 Posts: 227 Comments: 469
70. rwdobson
9:57 PM GMT on April 12, 2006
buster, colby is also thinking that has a chance. there is a lot of dry air around it though.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
69. rwdobson
9:55 PM GMT on April 12, 2006
No one's here so I had to answer my same question. Because the earth's orbit is elliptical, the distance from the sun varies by about 3 million miles over the course of a year. The Earth is closest to the sun in January and farthest in July, which means that the northern hemisphere gets a slight moderation in climate compared to the southern hemipshere.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
67. rwdobson
9:43 PM GMT on April 12, 2006
any astronomers in the house? what is the natural variation in distance from the sun along the earth's orbit? does that have anything to do with the variations in incoming solar rad?
Member Since: June 12, 2002 Posts: 0 Comments: 1589
63. louastu
5:22 PM EDT on April 12, 2006
What?
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61. DAVIDKRZW
9:10 PM GMT on April 12, 2006
2006 National Hurricane Conference in Orlando what is that all about did we this had that?
60. seflagamma
5:03 PM EDT on April 12, 2006
Dr Masters, thanks for the info.
Been meaning to ask you,
did you attend the 2006 National Hurricane Conference in Orlando this week. It started last Monday. Been several write ups in our local paper about some of the stuff.
Wondered if you attended or sent someone from your staff?

Anyway, thanks for all you do for us and this wonderful website!!!
Member Since: August 29, 2005 Posts: 299 Comments: 40920
59. rwdobson
7:52 PM GMT on April 12, 2006
Colby, thanks. I was thinking of ground-based solar radiation measurements, which have been around for quite a while...but to get an accurate picture of how much is being delivered by the sun (as opposed to how much is making it through the atmosphere) you would obviously need a satellite.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
58. snowski
7:45 PM GMT on April 12, 2006
Dr. Joe Sobel wrote:

Several people wrote to me with comments about my previous post concerning record snowfall and global warming and they made a good point. Their comments were that higher sea surface temperatures in the western Atlantic Ocean because of global warming could be leading to stronger storms and more nor'easters for the Atlantic Seaboard and hence higher snowfall. It is certainly a plausible theory, but I haven't seen any research that confirms that storms have been stronger or more frequent in the recent past. Perhaps some research on that subject will be done soon.
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57. ForecasterColby
7:41 PM GMT on April 12, 2006
Dobson, we really didn't have a way of measuring it directly before then. It requires a satellite, and those didn't become common until the late 70s-early 80s.
56. rwdobson
7:15 PM GMT on April 12, 2006
"rwdobson, one small mistake--greenhouse forcing is as yet still just over 2 watts/meter2. However, that number will increase as CO2 concentrations rise."

actually, that's a pretty big difference...but since the GHG forcing is constant, while the solar forcing seems to oscillate, I still think GHG would be more significant.

did we really not start measuring solar rad until 1979?
Member Since: June 12, 2002 Posts: 0 Comments: 1589

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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