Since the last hurricane related post, some news has occurred on the hurricanes front.
- Nature Geosciences article by Knutson et al. (2010) discussing the linkages between tropical cyclones and climate change / global warming — as an update to the IPCC AR4 statements
Whether the characteristics of tropical cyclones have changed or will change in a warming climate — and if so, how — has been the subject of considerable investigation, often with conflicting results. Large amplitude fluctuations in the frequency and intensity of tropical cyclones greatly complicate both the detection of long-term trends and their attribution to rising levels of atmospheric greenhouse gases. Trend detection is further impeded by substantial limitations in the availability and quality of global historical records of tropical cyclones. Therefore, it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes. However, future projections based on theory and high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2–11% by 2100. Existing modelling studies also consistently project decreases in the globally averaged frequency of tropical cyclones, by 6–34%. Balanced against this, higher resolution modelling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100 km of the storm centre. For all cyclone parameters, projected changes for individual basins show large variations between different modelling studies.
- Dr. Gray and Dr. Klotzbach released their December North Atlantic seasonal forecast (Above average…)
- Accuweather via Joe Bastardi previewed a doom and gloom 2010 Atlantic Season (Extreme…5 hurricane landfalls)
- The Southern Hemisphere TC season has become more active with Category 5+ Ului and a somewhat weaker companion storm Tomas. The brewing El Nino has provided plenty of favorable oceanic and atmospheric conditions for powerful storms in the Southwest Pacific.
A brief comment on the Knutson “consensus”: …told ya so.
Climate Audit 
79 Comments
Regarding the referenced North Atlantic 2010 hurricane predictions calling for above average activity, the 2009 North Atlantic ACE Index was 52, less than 1/2 of normal. The latter suggests that it would be unlikely that 2010 would be above normal in the North Atlantic, based upon known 30 year history of recorded ACE indexes. Maue doesn’t make predictions at his site though.
http://www.coaps.fsu.edu/~maue/tropical/
ryanm: i am Maue … why do you say this?
Sorry, I did not know who ryanm was — I do know.
I made my comment based upon the historical graph at your website. For the ACE to become “above normal” from the current <1/2 normal, it would need to more than double in less than a year. I do not see activity changes of that magnitude occurring on your graph — admittedly the period of coverage is limited to 30 years and is therefore a very small sampling. That is why I said "unlikely". Am I off base?
P.S. My youngest son spent several years at FSU in your department about 15 years ago. He remains a "hurricane enthusiast" to this day.
I think the diagram above is backwards. NH hurricanes rotate CCW and the diagram shows them rotating CW.
The diagram above is of two SH Tropical Cyclones as stated above that with a link to NOAA.
I think they are in the SH
http://www.sailwx.info/hurricanes/hurricanes.phtml
Definitely SH. Outlines of the northern half of the North Island of New Zealand, and the eastern seaboard of Australia are clearly visible.
To RyanM:
To a naïve observer of temperatures, the difference of temperature between day and night would lead the observer to make extreme projections for the very near future. To a more informed observer, the differences of temperature between summer and winter would lead to equally extreme, but merely more distant projections. Projections, it would seem, to a naïve consumer of projections, have the quality of being consistently, and perhaps unavoidably, too extreme.
I live in a hurricane prone area, and I have shared the experience of many others who have discovered suddenly that Nature can overwhelm all of their perceived limits on Nature’s powers and all the fancied protections they thought afforded by modern technology. What a hurricane can do to your family, to your property and to your whole mental outlook is no joke. Projections of hurricane potential of 2 to 11% here and 6 to 34% there, balanced by a 20% increase on the other side is very interesting in some ways, but I won’t be able to check the accuracy of those projections in 2100 as other factors are likely to intervene.
From what I can see, estimating trends accurately is very difficult; estimating variability is much harder; and, predicting when and where Nature’s hand will fall upon your personal head is next to impossible. That said, what do you think the value of estimating trends might be? To me, estimating variability, though harder, seems more useful.
Some further comments from the authors here:
http://abcnewswatch.blogspot.com/2010/02/abc-cyclone-report-leaves-questions.html
and interesting article in press at GRL
Wang, B., Y. Yang, Q.-H. Ding, H. Murakami, and F. Huang. Climate Control of the Global Tropical Storm Days (1965-2008) Geophys. Res. Lett., doi:10.1029/2010GL042487, in press (accepted 9 March 2010). In the abstract this article reports:
“However, the global total number of storm days shows no trend and only an unexpected large amplitude fluctuation driven by El Niño-Southern Oscillation and PDO. The rising temperature of about 0.5oC in the tropics so far has not yet affected the global tropical storm days.”
ryanm: This has been published elsewhere — GRL tends to re-publish findings for some reason. Since the authors did not pose a hypothesis about “how” the rising SSTs would affect global tropical storm days, they cannot reject the idea out of hand as they did. Not a good methodology.
From a methodological and epistemological viewpoint, asking “how” a factor causes a trend in some variable would be pointless if the trend itself is in question. What the cited work does is pointing out that no trend is discernible. The null hypothesis works the other way: in this case, the null hypothesis is that no trend exists in hurricanes in connection with observed 0.5°C warming; if you cannot reject that hypothesis, as the authors say you can’t, then it is useless to linger on any theory of “how” (or why) it happens.
Looks like Queensland’s Big Wet isn’t over by a long chalk. According to here, Brisbane’s dams are 93% full (which is impressive considering that three years ago they were at 16% and Tim Flannery was predicting that Brisbane would have to be abandoned (or was it Perth?)
Don’t forget the South Eastern US. Atlanta reservoirs were about empty and it was, of course, blamed on AGW. not exactly drought stricken now,
Yeah, the end of a lot of hyped drought conditions hasn’t gotten much press.
Do you know how the categories of drought are defined or ascertained?? I live in the unusually dry/moderate drought area marked with a big H just north of Lake Ontario. We have had a very mild winter with low snowfall, but the last two summers and the previous two winters were unusually cool/cold and wet/snowy. I find it hard to believe we are in the midst of even a mild drought. Or am I confusing weather with climate??
Does this help?
I looked at the Toronto stats: average annual precipitation (1971-2000) 792.7 mm. Accumulated precipitation Mar 13 2009 to Mar 13 2010 is 825.3 mm.
It was a mild winter, but I ain’t seen no drought.
As one suffering through the big wet, I can tell you the rain doesn’t even look like ending soon. I think I’m up to about 400mm of rain for March in my measurements. And it’s still raining.
The dams in QLD were always a political problem, not a rainfall problem. The effect of doubling population over a 20 years period and not building a single new piece of water infrastructure during that time is all you need to know. It’s the realization of the effects of ‘green’ policies – which translates to build absolutely nothing anywnhere near anybody. Doubling consumption while holding supply constant will do that. It’s only because of the naturally rainy climate (subtropical) that the dams got refilled in time.
A brief comment on the Knutson “consensus”: …told ya so.
Ok, where is the link to the “told ya so” part. That seems to be missing.
All I get from this is that the frequency of TC will decrease, but the intensity will increase, and that there is no apparent relation to AGW. And that this may just be due to natural causes.
Ryan, what is the meaning of a statement that intensity will increase (or decrease) 2%? Are intensity measurements that precise?
ryanm: nope, but that number comes from a climate model output — which provides intensity numbers from storms to the tenth decimal…not the 5 knots increments as the historical data. …2% would be undetectable until the end of the 21st century, if at all, as Bender et al. (2010) Science suggest
Let me see if I get this correct. What will reveal a reliable trend in the short-run will not be related to global warming, but where a trend can only be discerned over a much longer period and with much greater uncertainty is going reflect global warming. That seems to contain the key elements of a Ponzi scheme.
Hm…Gray and Klotzbach’s forecast is surprising, given the ongoing El Nino-do they have reason to believe that it will dissipate in coming months?
From the MEI Enso Index Page — http://www.esrl.noaa.gov/psd/enso/enso.mei_index.html
Based upon the previous transitions from La Nina to El Nino, the following has happened:
Sorry, off topic, but have you seen these comments?
http://www.quadrant.org.au/blogs/doomed-planet/2010/03/smearing-steve-mcintyre
Some people have nasty little minds.
Re: Pops (Mar 14 16:39),
Ya, and they missed the irony of Steve Mc’s “mole” joke…It was Phil Jones, himself. There are several related threads, maybe search for mole.
That article is laughable. Like a juvenile novel. Who knew SM was so diabolical? He must be drinking too much Big Oil.
But here’s the funniest line:
“In fact, as the U Penn investigation found, these claims were baseless.”
“future projections based on theory and high-resolution dynamical models”
Nothing based on the real world?
The models fail to hindcast, and the predictions are just as good as an Ouija board, and for this they waste paper and Internet bandwidth?
The data simply aren’t good enough to detect such a trend (As Ryan notes, wind speeds are given in very coarse increments, and besides that there is always the question of homogeneity). Thus in the absence of reliable and adequate observations, they are left with models. Far from ideal but if people demand scientific insight, well, scientists will try to supply it, in any form they can.
Of course, for the conspiracy minded, perhaps they were motivated by being unable to find any observations which supported their projections!
But I’ll stick with the data being unable to test the models as of now as the reason, since the report is hardly written by the Cabal.
Re: George M (Mar 14 17:16),
Watch out for the term “high resolution” when it comes to models. “High resolution” data can be run through low or intermediate resolution models, for example.
This website sucks as usual. I can prove global warming is destroying the planet but you all of you be like this is a plot by the oil companies that want carbon trading credits to make them richer. so you can on working for cap & trade … you are clowns.
Re: Ale Gorney (Mar 15 03:55),
Another example of why one should not drink and surf.
Re: Sleeper (Mar 15 05:09),
My favorite: “Don’t Drink and Derive”.
yep – Global Warming – it must be – because it ain’t the ones you are after your money. Check out here:
http://www.washingtontimes.com/news/2010/mar/03/global-warmings-biggest-winners/
This is off topic, but I am posting here as it is the most recent post and has the most visibility.
Steve M has been subjected to a disgusting and possibly
illegal smear by an Australian ¨Academic¨ in other words
a lefty economist.
http://johnquiggin.com/index.php/archives/2010/03/12/climategatethe-smoking-gun/#more-8331
More news at Australian journalist Andrew Bolt´s blog.
Word’s spreading:
Let’s try to stay on topic here. Ryanm, the told ya so reference above is very helpful for background. Thanks for including it.
Question for Ryan on modeling. I like Cliff Mass, et al, and their ‘micro-meso’-scale weather models. I sorta know what the hassles might be. I’m assuming specialization, region-wise, but how does one pull it together?
IIRC, there’s a PNW 2.5Km under testing/operation and NWS has it under testing. That should dovetail into regional hurricane models, for example, shouldn’t it?
You can download and run your own WRF mesoscale model and ramp it up to 2 km or less and initialize hurricanes to your heart’s content. There are Windows versions … and with the power of desktop computers, you can slowly do your own research at home.
The equivalent for the operational forecasting is HWRF and GFDL. The former is a failure while the latter has been used for a decade with decent track skill, not for intensity, however. Resolution increase doesn’t get you too much — when you don’t know how to initialize the storm at time=0 — the benefits are hard to determine.
Re: Ryan Maue (Mar 15 16:23),
Thanks for that.
I recall Algore even presented a picture of a hurricane with reversed rotation. It is going to be bad. Maybee even worse than 2009 was in North America.
I have not paid my money to see the main contents of Knutson et al., but the author list being the cross section of opinions that it appears to be, leads me to interpret the motivation for the paper being that we as group cannot probably agree on what the past data is telling us so we will write a joint paper with ranges of predictions that will satisfy all the authors.
The abstract says we can expect fewer TCs but more intense ones by way of model results. Fewer ones because of the expected effects of increased shear?
Is there a consistent theory that ties all these predicted occurrences together in a neat package or are we looking at a conglomeration of bits and pieces of separate model results?
Hi Ken…finally a hurricanes post.
The Knutson et al. (2010) paper is a “review”, there is no new research.
The reasoning for fewer weaker storms escapes me — and I haven’t read anything that would suggest as such. I would think we would have more seasons like 2005 with lots of strong hurricanes and a dozen Baby Whirls, many of which developed outside of the tropics due to non-tropical forcings (so-called tropical transitions).
In my opinion, we need new ideas and researchers in this field in order to get rid of the group think in the TC community — which has finally been shattered with the new Knutson consensus. It took a while, but finally Emanuel (2005) and Webster et al. (2005) are no more.
Hurricane history in the Atlantic and Eastern Pacific over last 100 years from NOAA:
http://www.nhc.noaa.gov/pastprofile.shtml#cp100
OT but SM your reticence is admirable considering all that has happened over the past 48 hours.
Re: Sean Peake (Mar 16 17:24),
I think he’s out in the wilds panning for gold or something like that. Probably has no way of replying even if he’s heard about recent silliness.
I know John Christy likes to pan for gold but I think Steve’s hobby is Squash.
Re: timetochooseagain (Mar 16 20:17),
No, Steve’s favorite food is squash, but John likes pancakes.
I’ve just put together this: Running ten year total landfalling US Hurricanes and Major Hurricanes.
Thought people might find this interesting.
Oh, References:
http://www.aoml.noaa.gov/hrd/tcfaq/E23.html
http://www.aoml.noaa.gov/hrd/hurdat/ushurrlist18512008.txt
Hello Steve
Let me introduce myself,
My name is Redmond Weissenberger, and I have been following the climate debate for the last five years.
I have finally decided to add my two cents to the debate, and I am launching an educational campaign in Toronto.
I am giving a lecture to two sessions of a 1st year Poli-Sci at York University Tomorrow and Friday.
The lecture is entitled AGW, the Politicisation of science, and the green agenda.
In addition to working through the science, I will also be highlighting the ability of laypeople such as yourself to have effect on the debate. And to turn the course of history as you and Ross did – maybe we can
inspire some kids.
I am also involved in Donna Laframboise’s Citizen Audit of the IPCC.
I have been corresponding with Dick Lindzen, Albert Jacobs, and Fran Manns of the Friends of Science, and Warren Meyer of Climate-Sceptic.com – I have incorporated slides of theirs into my presentation, and am using information that they have passed on.
I was wondering if you had a 2 to 3 paragraph write up on the history of your involvement of the hockey stick – you questioning the data, requesting it from Mann, and doing the statitical analysis with Ross.
If you have the time to spare, it would be most appreciated.
I know the outline of the story, but having a direct quote from you would be wonderful.
Best Regards
Redmond
Good luck with walking into the zombie nest. Love to see your presentation. And I hope you actually get to speak without being shouted down.
And all we have to do is wait a hundred years to find out if the predictions are correct or not.
Until then, we should collect higher taxes just in case we’re correct.
yeah.
Hi Ryan,
Any ideas on why
(a) many major hurricanes and topical stoms east of USA landmass tend to cross the coast at 90 degrees angle
(b) many of same do a right angled turn a few hundred km out to sea and then head for land.
Similar for N-W Australia cyclones. They trace roughly south-west for several days and then turn left 90 degrees for landfall.
Turn is right in NH, turn is left in SH so one suspects driving by mormal circulation patterns. The incidence of these events seems far more common than chance.
The storms west of USA seem to run more straight and do not do right angles.
Here’s a thought: my understanding is that TC frequency is thought to have not changed, and ACE seems to not have changed in recent decades, although variable, if it were in fact true that they had become stronger, they must be more short-lived. Has this in fact occurred and has anyone discussed how or why such a decrease in duration could occur?
Folks might be interested, especially given claims that Cat 4/5 hurricanes are increasing, in Chris Landsea’s talk a AMS’s 22nd Conference on Climate Variability and Change (2010):
http://ams.confex.com/ams/90annual/techprogram/paper_163059.htm
He says that of the ten most recent category fives, only two would likely have been registered as category fives if they happened in 1945.
What is increasing is not cat 4/5 hurricanes, but the prediction of same. Much easier to make the predictions than it is the hurricanes. Does anybody keep track of how far off the mark, even with the inclusion of every Tiny Tim that can be divined out of a puff of wind, these predictions turn out to be.
It seems if they miss we just say, WOW am I glad. Why bother listening to them.
Question:
Can anyone point me to documentation that links the colors in the IR image for the hurricane at the top of this to temperature?
I would appreciate this as we are doing some work with older satellite IR data and would like to be consistent.
This seems relevant-a discussion of recent research on Southern Hemisphere TC’s
http://www.worldclimatereport.com/index.php/2010/03/30/southern-hemisphere-hurricanes-–-not-changing/
The First reference happens to be fascinating, especially WRT the claim of increasing intense cyclones:
Kuleshov, Y., R. Fawcett, L. Qi, B. Trewin, D. Jones, J. McBride, and H. Ramsay (2010), Trends in tropical cyclones in the South Indian Ocean and the South Pacific Ocean, J. Geophys. Res., 115, D01101, doi:10.1029/2009JD012372.
From the Abstract, a couple excerpts:
“Positive trends in the numbers of 945 hPa and 950 hPa TCs in the SIO are significant but appear to be influenced to some extent by changes in data quality.”
“In the Australian region, no significant trends in the total numbers of TCs, or in the proportion of the most intense TCs, have been found.
Southern Hemisphere activity is roughly normal for 2009-2010 after a record low year. Many previous studies’ assertions about increases in global cyclone intensity were made without taking into account the quality of the data and have been largely dismissed.
It seems Makarieva et al 2010 will open some questions into the energy law problem in the ‘standard’ hurricane model (and also into the dissipation problem with GCM’S )
Makarieva A.M., Gorshkov V.G., Li B.-L., Nobre A.D. (2010) A critique of some modern applications of the Carnot heat engine concept: the dissipative heat engine cannot exist. Proceedings of the Royal Society Series A
Abstract
In several recent studies, a heat engine operating on the basis of the Carnot cycle is considered, where the mechanical work performed by the engine is dissipated within the engine at the temperature of the warmer isotherm and the resulting heat is added to the engine together with an external heat input.This internal dissipation is supposed to increase the total heat input to the engine and elevate the amount of mechanical work produced by the engine per cycle. Here it is argued that such a dissipative heat engine violates the laws of thermodynamics. The existing physical models employing the dissipative heat engine concept,in particular the heat engine model of hurricane development, need to be revised.
Notes:
The critique presented in this paper has a rich history, see here. Its major goal is to make space for a constructive consideration of the rich physics of the condensation-induced atmospheric dynamics — the major physical principle of the biotic pump of atmospheric moisture. In the press release devoted to this paper we wrote:
In a quest to understand the nature of atmospheric motions, a thermodynamic view on the atmosphere as a heat engine of some kind has become quite wide-spread. In our work we show that the dissipative heat engine where mechanical work output is supposed to grow due to internal dissipation of work produced in the previous cycles, is thermodynamically inconsistent and cannot exist. Our results indicate that the models employing the dissipative heat engine, in particular, the hurricane model of K. Emanuel, are incorrect.
This paper belongs to the series of papers on a new physical mechanism of atmospheric dynamics developed by our group. The physical core of this mechanism consists in the fact that condensation of water vapor reduces air pressure via removal of vapor from the gas phase. This leads to formation of spatial pressure gradients and thus initiates atmospheric circulation on a variety of spatial and temporal scales. In another recent paper published in November 2009 in Physics Letters A, Condensation-induced kinematics and dynamics of cyclones, hurricanes and tornadoes, it was shown that this approach yields a unified quantitative description of hurricanes and tornadoes.
However, the most important implication of the new approach concerns the role of forests in sustaining the water cycle on land. Since condensation reduces air pressure, intense condensation of water vapor associated with evapotranspiration of natural forests creates regional areas of low pressure. In the result, moist air flows from the adjacent ocean to the continent, thus compensating for the loss of water to the ocean via the river runoff. Deforestation reverses the ocean-to-land atmospheric moisture flow thus locking the continent for ocean moisture and induces rapid desertification. Conversely, restoration of a contiguous, spatially significant forest cover protects the continent against extreme weather events like both floods and droughts.
These ideas are new to the meteorological community and have been met with some resistance. This prompted us to take a critical approach to the established meteorological lines of thought (like viewing the hurricanes as a heat engine) to show that they do not provide a satisfactory explanation of the atmospheric phenomena and that there are both space and need for developing new theories.
In connection to the recently hacked CRU e-mails, the community of climate scientists has been criticized for possible distortions of the peer-review process that would keep unorthodox ideas out of the mainstream literature. In our view, our critical paper in the Proceedings of the Royal Society Series A might be a good opportunity for external observers to follow how the mainstream climate science would respond to a critique of its physical fundamentals and to what degree it is receptive to new ideas in atmospheric physics.
http://www.bioticregulation.ru/pubs/absn.php?ref=dhe&lang=en
Re: maksimovich (Apr 3 18:42),
I agree.
I see Ryan has put up a graphic of the West Pacific basin PDI:
It’s interesting that even with the known bias in wind speed estimates prior to 1988 (see here for instance) that the PDI trend has been essentially negligible.
I also see some pretty clear ENSO effects.
An interesting observation about the West Pacific-tracks seem to have shifted-in recent decades rather than striking China they seem to be favoring Korean and Japanese landfall-based on some of Johnny Chan’s work, this appears to be related to atmospheric factors, which goes to show that there are a lot of factors involved in determining when, where, and how bad these storms get. If Hurricanes in the Atlantic were to shift favoring say, New England over Florida and the Gulf, that would have serious implications even if no obvious connection to AGW exists. It seems to me based on paleo evidence that the historical record has been very misleading to us about what nature is capable of-there are very real risks from tropical cyclone variability which are A. Not understood and B. capable of representing much more serious problems than a change in the tropical cyclone climate due to AGW per se.
Here’s an example of some weirdness with regard to the intensity estimates: Between 1973 and 1994 there were apparently no Category 5’s in the East Pacific at all. Oddly enough that 1973 cyclone, Ava, happens to have been unusually well observed. It was even photographed by Astronauts aboard Skylab. Heck of a coincidence if you ask me. And there were no lack of category fours between 1973-1994.
And by the way, in spite of potential biases, the trend in cat 4 and 5 in EPAC is negative in the last thirty years.
More 4/5 info-so far I’ve managed to figure out the global official numbers since 1995 (I think I’ve figured them out anyway). Putting SH 4/5 into the first year of their season, I get:
1995 18
1996 19
1997 21
1998 15
1999 15
2000 10
2001 14
2002 22
2003 17
2004 25
2005 22
2006 17
2007 14
2008 13
There is no trend so far (almost one fewer storm on average but I’d bet anything it isn’t significant and the period is very short)-It seems rather unfortunate that so many studies on intensity were published in 2005, right after globally busy year for cat 4/5. Probably skewed impressions a bit.
Proving that I’m the biggest dolt in history, I forgot the Northern Indian Ocean. The correct values for those years should be
1995 18
1996 20
1997 22
1998 15
1999 17
2000 10
2001 14
2002 22
2003 17
2004 25
2005 22
2006 18
2007 16
2008 14
Still no trend over an admittedly short period. Now I’m off to correct a very misleading analysis of did of the Northern Hemisphere where I forgot the North Indian. GACK!
Oops, copied the wrong list! UGH! This is the right one:
1987 13
1988 16 14
1989 16 18
1990 14 15
1991 22 15
1992 23 28
1993 17 17
1994 20 21
1995 18 15
1996 20 18
1997 22 26
1998 15 13
1999 17 16
2000 10 16
2001 14 10
2002 22 20
2003 17 18
2004 25 24
2005 22 22
2006 18 20
2007 16 18
2008 14 14
2009 14
Okay, I see it still isn’t copying right-The list was okay it was a spacing error. Just imagine that the 14 in 2009 is over in the second column.
Here’s something fishy-in the Southern Hemisphere there is a weird step increase in 86 knot and up counts (note this graph is taken from a conference paper which miss-identifies these as Cat 4/5, the paper itself misidentifies these as being on the Australian scale, these really correspond, roughly, to major hurricanes, and Beaufort numbers 14 and up) in ’86.
But this is very likely not real! The Infrared Dvorak technique was only two years old at this point, not to mention the lack of satellite monitoring, especially in the South Indian region, was lacking in earlier years.
Yes, the lack of geostationary satellite coverage over the Indian Ocean and limited use of NOAA AVHRR polar orbiting imagery is apparent in that step-wise increase. The AVHRR microwave passes will be available at the IBTrACS site soon, which will help somebody figure out how many Cat 4/5 have been missed. Likely a lot — but don’t let that get in the way of using that figure as evidence of global warming, like others have.
Why-in a physical sense-have there been fewer and weaker storms in the EPAC in recent years, compared to the late 80’s and early 90’s? My first guess is that it’s connected to moist static stability-the atmosphere in that basin in particular is the only one that appears to have gotten more stable, or less unstable. You can even see this in the Hoyos et al paper. So the important question to ask with regard to intensity trends is, with respect to the non-SST factors, how are they changing, and how can they be expected to change in the future. If they continue to change the way they have in the Atlantic, where wind shear, moist static stability, etc have ALL become more favorable, we’d see big increases in intensity. But models of future climate tend to predict the opposite, so the question is, are the trends in non-SST variables related to AGW or natural? Are the conditions becoming less favorable in the East Pacific due to AGW? If not, why are the conditions become more favorable in the Atlantic due to AGW? Sounds like a double standard. I think the most parsimonious explanation is that the regional climate’s independent variations are what counts for intensity in a basin, and these are natural-the factors probably won’t change as significantly in any way due to AGW given the varied spatial pattern and conflict with models of these natural variables.
BTW, my view that it is the regional climate variation that is not associated with the global change is very consistent with Vecchi and Soden’s work showing that MPI is approximated by subtracting tropical mean SST from MDR SST:
Vecchi, G.A. and B.J. Soden. 2007. Effect of remote sea surface temperature change on tropical cyclone potential intensity. Nature, 450, 1066-1071.
In my paper, I hypothesize that fewer African Easterly Waves of the required intensity/scale/flavor enter the Eastern Pacific basin since 1995ish for at least one reason: they develop first in the Atlantic or get steered away from the Central American crossing point. Thus, unfavorable conditions prior to crossing the landmass or the latitude at which they do, may have implications for EPAC development. The SSTs are always very warm in that mini-basin, so I am doubting it is related to AGW at all.
The tropical mean SST is a proxy for ENSO to a large extent.
Having re-read your paper I see that you did suggest that-and it is a very good point, especially with regard to frequency.
With regard to ENSO and the Tropical mean, yes that is a major component of it. Of course, outside of the ENSO region proper this response is damped. The effect then of the differencing that Vecchi and Soden (and Swanson) have been suggesting is to: Decrease the amplitude of ENSO events in the Pacific and reverse their sign in the Atlantic. So the differencing basically matches up well with the expectations of El Nino.
Also, when one does this the AMO very nicely emerges from the Atlantic. Unfortunately Vecchi and Soden completely skipped over the EPAC, so I haven’t a clue what that would look like.
Interestingly, despite the notion that AGW should decrease storm frequency and increase intensity, these two appear to be directly rather than inversely related in existing record. I don’t get how anyone thinks that these two phenomena could suddenly cease to be co-dependent.
By the way, Ryan, I’m not sure if you’ve seen this before, but there was a very interesting paper written on longer term East Pacific activity-obviously there are limitations before satellites but much like the reliability of US landfalls, those EPAC storms that hug the Mexican coast (which are a significant percentage of them) may be better counted. According to:
Englehart, P. J., M. D. Lewis, and A. V. Douglas. 2008. Defining the frequency of near-shore tropical cyclone activity in the eastern North Pacific from historical surface observations (1921–2005). Geophysical Research Letters, 35, L03706, doi:10.1029/2007GL032546.
There has been a long term decline in EPAC activity-they even looked at windspeeds and pressures, and average central pressures have been going up, windspeeds down, and there appears to be some decadal variability which reminds me of that in the NATL, but of course inverted. Look at the strong storms in the era of weak storms in the Atlantic, and in the fifties and sixties and today, those strong storms disappeared:
We’re all going to be in serious trouble with polar ice caps melting, rising sea levels and increased hurricane activity, most probably caused by shifting ocean temperatures.
Re: John (Jun 25 14:56),
I suspect you’re just trying to drive traffic to your blog, but it is about time to reactivate this thread as there’s news about a TS or TC brewing for the Gulf.
I will create a headline-post later tonight…
Where’s Judith Curry’s “%cat4/5” standard reply?
The FEBRUARY forecast was for 16-18 total
7 impact storms, 5 of which would be hurricanes, 2 major.
Impact was Way overdone. There have been 6 impact storms ( delivery of at least tropical storm force winds to the US coast from a storm of tropical origin, only 1 a hurricane ( Earl..I did not count Alex as a hurricane impact in spite o hurricane warnings on the Texas coast. ). Obviously no majors as of this writing
Please do not misuse impact and landfall. My forecast was overdone enough without the exaggeration. The fact is that landfall, like total number, is over-rated. The question is what happens to a given site with a storm that had tropical origin. Example:
Ernesto did a half billion dollars damage after it was downgraded. You are correct in saying I am overdone on impact. But remember last year I was leading the pack in saying little activity ( march forecast) the year before nailed the high impact season. Those that have watched me over the years, have seen that ideas from 02-05 were very good, if not underdone in 05. 07, like this year, was not a year I can point to with any degree of satisfaction. So I am aware of that aspect. And total intensity this year was no where near normal but bordering on hyperactive ( since I think there are two more developments, it will get to hyper active levels)
There is enough right and wrong so that no one out there I saw nailed the season. If you want to say 16 storms, 5 or 6 majors is a normal year, that is simply wrong.. I admit the impact idea on my part is overdone, but lets make sure we understand what I am forecasting.
Note: I have specifically directed my company to make sure that in using my forecast we use impact, not landfall, where impact is defined as the actual weather caused by a storm of tropical origin. If there was confusion, there should be none now.
Why the high impact score so early. I simply took the mean of years that had the kind of ace index I believed would occur (150-200) and played the mean of those years. From 5 months out, the forecast for such a high number was being scoffed at, but if someone told you, as a scientist, there was going to 16-18 storms and 5 majors arguably 6 ( Alex was 947 mb with a 12 mile wide eye) what would have been your impact conclusion on the US coastline. The fact is that until May, the other big guns in the forecast debate did not have as active a season coming s I had put out in February .
I am not justifying the US impact forecast as much as saying that if you thought the season was going to be normal, perhaps
you should look in the mirror before throwing the stones
All the best
JB
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