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UPDATED: Anyone wishing to claim that intense storms are not getting more intense should read The increasing intensity of the strongest tropical cyclones by James B. Elsner, James P. Kossin2 & Thomas H. Jagger before making a fool of themselves
For the Western North Pacific basin since 1981, Elsner,et al find that the speed of the fastest typhoons, e.g. the Cat 5s corresponding to the last two columns, the worst 2.5% or 1% of the 698 storms in the basin, have significantly increased
| Statistic | Quantile | |||||
| 0.85 | 0.90 | 0.95 | 0.975 | 0.99 | ||
| 698 typhoons | Western North Pacific | |||||
| W (m/s) | 58.9 | 63.7 | 69.6 | 73.1 | 77.6 | |
| Trend (W/yr) | 0.12 | 0.14 | 0.09 | 0.29 | 0.36 | |
| S.E. (W/yr) | 0.190 | 0.177 | 0.192 | 0.116 | 0.023 | |
| P | 0.520 | 0.434 | 0.647 | 0.012 | 0.115 | |
| W (kph) | 212 | 229 | 251 | 263 | 279 | |
| W (mph) | 132 | 143 | 156 | 164 | 174 | |
Kevin Trenberth and Jeff Masters will be PBS Newshour at 6:12 EST today to talk about Haiyan.
This is obviously a difficult issue to speak to with certainty, primarily because disparities between the various storm track databases.
ReplyDeleteThe very latest literature does support the work of Elsner et al. and the claim that Sachs made, that globally the strongest TCs are getting stronger.
From Kossin et al. (2013, in press in J. Clim.), my annotation in square brackets is from the paper's body text:
"Our analyses using a new homogenized record of tropical cyclone intensity suggest that the stronger tropical cyclones, globally, have become more intense at a rate of about +1 m s− 1 decade−1during the 28 -yr period 1982– 2009, but the statistical significance of this trend is marginal [p-value = -0.1].
Dramatic changes in the frequency distribution of Lifetime Maximum Intensity (LMI) have occurred in the North Atlantic, while smaller changes are evident in the South Pacific and South Indian Oceans, and the stronger hurricanes in all of these regions have become more intense. There are no significant changes noted in the eastern North Pacific, and negative changes are found in the western North Pacific, that is, the strongest hurricanes have become weaker. There are insufficient data to determine trends in the distribution of LMI in North Indian Ocean hurricanes."
So what Sachs said is correct, but the data do not seem to support his assertion concerning TCs over the western tropical Pacific, at least for the period 1982-2009.
Before accusations are made about cherry picking by certain "honest" brokers, the authors in Koppin et al. provide very sound reasons for going back to 1982 and not earlier.
Check the SSTs.
ReplyDeleteHaiyan passed over normal to slightly cooler than normal waters as it intensified to cat 5.
Not really, Anom: http://www.ospo.noaa.gov/data/sst/anomaly/2013/anomp.11.7.2013.gif .
ReplyDeleteWe also need to know a little more about the layer from surface to -200m.
After the Haiyan's passage the SST in that region just east/southeast of the Philippines dropped to slightly cooler than normal. That's what great cyclones like that do - dissipate the top ocean heat into kinetic energy and radiation to the moon, leaving upchurned cooler waters in their wake.
This effect actually bars a follow-up of any comparable strengh over that path.
Anon,
ReplyDeleteRe SSTs link to image and data pls. what date? What baseline?
Hadl/Rey V2 SST data show SSTs were mostly slightly above the 1951-1980 baseline for October along the storm's track.
http://data.giss.nasa.gov/tmp/gistemp/NMAPS/tmp_GHCN_GISS_HR2SST_1200km_Anom10_2013_2013_1951_1980/nmaps.gif
At the time of the storm, other data show SSTs near normal at the time of the storm but relative to the 1981-2010 baseline (dynamic page, so look quickly):
http://www.esrl.noaa.gov/psd/map/images/sst/sst.anom.gif
The surface is not the whole picture-- what was the depth of the 26 C isotherm?
The storm had a lot of latent energy to tap into, see:
http://www.nnvl.noaa.gov/MediaDetail2.php?MediaID=1452&MediaTypeID=1
Here it is. Haiyan's track and temp anomalies at -100m.
ReplyDeleteDr. Masters just put it on: http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2579
(had to trash that. Since wide-eyed typhoon Krosa got shot out of existence while doing the Chinese island of Hainan I'm constantly calling Haiyan 'Hainan')
Sigh, Roger Rabbit junior is upset with me again for exposing his game. So now he has resorted to not posting a comment of mine and limiting me to one post a day. Like I just told him "Run Rodger, run!"
ReplyDeleteSo if Eli does not mind I'll post my comments here as well in case Roger disappears them.
"15. Albatross said...
Roger,
Oh dear, you need to please carefully read my post again and you also need to carefully read the tweet made by Sachs that upset you so...he said "disasters like Haiyan" (i.e., globally and the strongest TCs).
Kossin et al agree with Elsner et al. that globally the strongest TCs are increasing in strength at the 90% level of confidence (more than that in some basins). The papers differ in one region, the WNP-- I made that clear in my post.
And when you are not trying to score points, maybe you and your readers here could contribute something useful and positive by helping classifying over 30 years worth of TC data:
http://blog.cyclonecenter.org/2013/06/13/a-better-cyclone-center/
Thanks!"
And another, he really did not like this one!
ReplyDelete"Oh Roger, come on, please don't council me on snark, you are incredibly snarky yourself ;)
My snark was justified as you are and were misrepresenting what people said to try and score points.
I accept your silence on the subject of you misreading my and Sachs' comments as tacit admission that the premise of your argument was a straw man and a shifting of the goal posts. Why?
Sachs was talking the strongest TCS increasing in strength globally, but then you start arguing about landfalling hurricanes in the WNP.
Maybe you could explain to your readers why 50% of the ten strongest landfalling hurricanes have occurred since 2000, 70% since 1990.
Grinsted's analysis also shows positive trends in the strength of the strongest TCs (top 90%, 97.5 and 99%) over the WNP extending the JTWC WNP data beyond 2010. Pity Aslak did not say whether or not the trends are statistically significant or provide the trends. Regardless the trends are positive over the WNP (top 90%, 97.5 and 99%), in agreement with Elsner et al..
Thanks!
PS: Re cyclone center, it cannot hurt to have better data to work with. "