{"id":413,"date":"2007-03-01T17:52:25","date_gmt":"2007-03-01T22:52:25","guid":{"rendered":"\/?p=413"},"modified":"2007-05-07T15:33:30","modified_gmt":"2007-05-07T20:33:30","slug":"hurricane-heat","status":"publish","type":"post","link":"https:\/\/www.realclimate.org\/index.php\/archives\/2007\/03\/hurricane-heat\/","title":{"rendered":"Hurricane Heat Kas\u0131rga Ate\u015fi<\/lang_tk>Chaleur d’ouragan<\/lang_fr>"},"content":{"rendered":"
\n

The big problem with much of the discussions about trends in hurricane activity<\/a> is that the databases that everyone is working from are known to have significant inhomogeneities due to changes in observing practice and technology over the years. So it’s not surprising that a new re-analysis (Kossin et al<\/a>, published yesterday) has been generating significant interest and controversy among the hurricane research community (see e.g. Prometheus<\/a> or Chris Mooney<\/a>). However, rather than this study being taken for what it is – a preliminary and useful attempt to make homogeneous a part of the data (1983 to 2005) – it is unfortunately being treated as if it was the definitive last word. We’ve often made the point<\/a> that single papers are not generally the breakthroughs that are sometimes implied in press releases or commentary sites and this case is a good example of that.
\n<\/p>\n

Kossin et al develop an algorithm based on North Atlantic data that can be theoretically used with the coarsest data available from the earlier parts of the record and in more remote regions. While the technique works well in the North Atlantic (picking up almost all of the storms seen in the standard data), it doesn’t work as well in other basins – possibly because the characteristics of tropical cyclones are not universal, or because the coarse early remote sensing data are still not sufficient. The poorer performance in the other basins is surely a reason to anticipate that further work will be necessary to refine these estimates, and should serve as a caution to those wanting definitive conclusions. <\/p>\n

How does this fit in with some of the previous work<\/a>? Well, it confirms the large trend in the North Atlantic (seen in Emanuel, 2005), but doesn’t show significant trends in the other basins (from 1983). This isn’t directly comparable with Webster et al (2005) though, since their trends start in the 1970s, and the shortness of the new reanalysis (only 23 years) emphasizes interannual and decadal variability<\/a> associated with e.g. El Nino. The Kossin et al study is therefore unlikely to shed much light on the potential global warming\/hurricane intensity link<\/a>. <\/p>\n

In summary, read the papers and the comments but don’t believe the hype. <\/p>\n

We’ll start off the discussion with a few comments we have already received on the provocative study:<\/p>\n

<\/p>\n

1. Chip Knappenberger<\/a>:<\/p>\n

\n

\nBased upon the new results of Kossin et al. <\/a> (GRL, 2007), it looks like the IPCC SPM just barely<\/em> covered itself in its proclamations on observed hurricanes:
\n
\nThere is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures. There are also suggestions of increased intense tropical cyclone activity in some other regions where concerns over data quality are greater. Multi-decadal variability and the quality of the tropical cyclone records prior to routine satellite observations in about 1970 complicate the detection of long-term trends in tropical cyclone activity. There is no clear trend in the annual numbers of tropical cyclones.<\/em><\/p>\n

From the results presented in Kossin et al. the “suggestions” of increases in intense tropical cyclone activity in regions other than the Atlantic basin are not really so well supported, at least for the last 23 years. <\/p>\n

We’ve tried to make this point a bit more clearly here<\/a>, despite the implications of the headline of Kossin’s press release<\/a>.<\/p>\n

-Chip
\n(disclosure: I have, to some degree, been funded by the fossil fuel industry since 1992)\n<\/p>\n<\/blockquote>\n

2. Dr. Kevin Trenberth<\/a>:<\/p>\n

\n

1) The methodology is trained on the Atlantic. It has no parameters to allow for different structures or size of storms, and there is no good reason why it should work well on storms in other basins. Given the different land-sea configurations and the different role of ENSO in the different basins, and the fact that disturbances in other basins do not form from easterly waves from off of Africa, there is every reason to expect that storms in other basins have different characteristics. For instance, there is greater activity in the Pacific Northwest, and the tropopause is higher in the western Pacific, and this affects brightness temperatures at tops of clouds. If the size of storms differs then the fixed form of EOFs will not be able to capture that form. The analysis must be able to account for differences among basins in order to have confidence in variability or trends. It would be easy enough to test whether the storms in other basins had different characteristics by also performing an EOF analysis for each region. This basic test was not done. It should be.<\/p>\n

2) The results are suggestive of these problems. In the SIO where the method gives 0, 1 or 2 storms vs up to 6 in the best track data, there is a serious bias. Similar large biases exist in the SPAC (up to 2 vs 5 in best track). Obviously the threshold is effectively different and it is a comparison of apples and oranges.<\/p>\n

3) In addition, this version of the paper deals with PDI. The earlier version of the paper dealt with intensity of storms and that was abandoned because the results were not very good. In particular, the presumption is that the older results were the problem because operational methods have improved. But the Kossin et al results showed bigger and greatest discrepancies with those from best track in recent years: there is no convergence over time. This is harder to see with PDI, because the biggest storms are emphasized, but the question of why is there not good agreement in recent years is not answered.\n<\/p>\n<\/blockquote>\n

3. Dr. Judith Curry<\/a>:<\/p>\n

\n

The most vexing thing about the tropical cyclone data sets is the uncertainty that analyst subjectivity contributes to this. The Dvorak scheme for determining tropical cyclone intensity is notoriously subjective, see the recent BAMS article<\/a> on this. The importance of what Jim Kossin has done is to take this subjectivity out of the analysis.<\/p>\n

Kossin’s method matches well the historical data in the North Atlantic (NATL) and East Pacific (EPAC). The method was trained using North Atlantic data, and the East Pacific regime in terms of dynamical and thermodynamical conditions is very close to the North Atlantic conditions. However, Kossin’s method diverges substantially from the established data sets in the Western Pacific, South Pacific, and Indian Oceans. Does this mean that the established data sets or in error, or that Kossin’s method (trained in the Atlantic) does not translate well to the other ocean regions?<\/p>\n

Owing to problems with dealing with historical satellite data, Kossin’s study was extended only back to 1983 (the period for which the satellite data are well calibrated), and it is almost certain that this data set cannot be extended back prior to 1977. By itself, this data set is too short to say anything about a trend in intensity. But it can in principle be used to assess uncertainties in the established data sets. <\/p>\n

My own analysis of the discrepancies has focused on the Western Pacific (WPAC) data, where 40% of the global tropical cyclones form. During the period 1983-1987, Kossin’s data overlaps with aircraft reconnaissance data; I would expect the WPAC TC data during this period to be of comparable quality to that in the NATL and WPAC, but large discrepancies are seen. I would also expect the agreement to be better in more recent years with the advent of more sophisticated satellite systems, but the discrepancies are largest during the most recent period. Its would not be surprising for this method trained in the NATL not to work well in the other regions. The method does not allow for different structures or sizes of storms in different basins. The NATL cyclones form primarily from easterly waves, while those in other regions do not. The role of ENSO is different in the different basins. The tropopause height is higher in the WPAC. etc.<\/p>\n

Many people in the tropical cyclone community have questioned the Emanuel and Webster et al. papers owing to uncertainties in the data sets. Other than anecdotal analyses, little has been done to quantitatively assess the uncertainties. Kossin’s paper is arguably the first important word on this subject, but it certainly won’t be the last word. To establish the credibility of Kossin’s data set outside the NATL, considerably more analysis is needed to understand discrepancies in individual basins and the nature of the discrepancies on a storm-by-storm basis.\n<\/p>\n<\/blockquote>\n

<\/small><\/p>\n


\nIngilizce\u2019den \u00e7eviren: Figen Mekik<\/small><\/p>\n

Kas\u0131rga olaylar\u0131ndaki trendler (e\u011filimler)<\/a> ile ilgili anla\u015fmazl\u0131klar\u0131n ana sebebi herkesin kulland\u0131\u011f\u0131 veri tabanlar\u0131n\u0131n aras\u0131nda b\u00fcy\u00fck benze\u015fmezliklerin olu\u015fu. Bu uyu\u015fmazl\u0131klar\u0131n k\u00f6k\u00fcnde y\u0131llarca s\u00fcren ve birbirine benzemeyen g\u00f6zlemleme usulleri ve teknolojik farkl\u0131l\u0131klar var. Dolay\u0131s\u0131yla, yeni bir analizin (Kossin ve digerleri <\/a>, d\u00fcn yay\u0131nland\u0131) kas\u0131rga arast\u0131rmac\u0131lar\u0131 aras\u0131nda \u00e7ok b\u00fcy\u00fck ilgi ve polemik yaratm\u0131\u015f olmas\u0131 \u015fa\u015f\u0131rt\u0131c\u0131 de\u011fil (mesela, Prometheus<\/a> veya Chris Mooney<\/a>). Ancak bu \u00e7al\u0131\u015fmay\u0131 oldu\u011fu gibi kabul etmek yerine \u2013 yeni ve kullan\u0131\u015fl\u0131 bir homojen (tekt\u00fcrel) veri taban\u0131 (1983 -2005) olmas\u0131 \u2013 \u00e7ok ki\u015fi maalesef son s\u00f6zm\u00fcs gibi okuyor. Biz, pek \u00e7ok kez belirtti\u011fimiz gibi, hi\u00e7 bir tek \u00e7al\u0131\u015fman\u0131n medya veya ba\u015fka yorum sayfalar\u0131nda sunuldu\u011fu gibi b\u00fcy\u00fck bir geli\u015fme muamelesi g\u00f6rmesi taraftar\u0131 de\u011filiz. Bu \u00e7al\u0131\u015fma da bunun g\u00fczel bir \u00f6rne\u011fi. <\/p>\n

Kossin ve di\u011ferleri Kuzey Atlantik verilerine dayal\u0131 bir algoritma geli\u015ftirmi\u015fler. Bu algoritma, tortusal rekorun daha \u00f6nceki k\u0131s\u0131mlar\u0131nda ve ula\u015f\u0131lmas\u0131 zor b\u00f6lgelerde kaba verileri kuramsal olarak kullan\u0131labilir hale getiriyor. Bu, Kuzey Atlantik\u2019te iyi sonu\u00e7lar veren bir y\u00f6ntem oldu\u011fu halde (standart veri tabanlar\u0131nda bulunan hemen hemen t\u00fcm f\u0131rt\u0131nalar\u0131 a\u00e7\u0131klayabiliyor), ba\u015fka havzalarda ayn\u0131 derecede ba\u015far\u0131l\u0131 olam\u0131yor. Bunun muhtemel sebebi tropik kas\u0131rgalar\u0131n \u00f6zelliklerinin evrensel olmay\u0131\u015f\u0131, veya \u00f6nc\u00fcl kaba verilerin yeterli olmay\u0131\u015f\u0131. Bu b\u00f6lgelerdeki ba\u015far\u0131s\u0131zl\u0131klar pek tabii ki algoritmalar ile yap\u0131lan hesaplar\u0131n ileride daha rafine olaca\u011f\u0131n\u0131 umud ettiriyor, ve ivedi kesin sonu\u00e7lar arayanlara bir uyar\u0131 olmal\u0131.<\/p>\n

Peki, daha \u00f6nceki \u00e7al\u0131\u015fmalarla<\/a> bu \u00e7al\u0131\u015fma aras\u0131nda nas\u0131l bir uyum var? Daha \u00f6nceden tespit edilen (Emanuel, 2006) Kuzey Atlantik\u2019teki b\u00fcy\u00fck \u00f6l\u00e7ekli e\u011filimleri do\u011fruluyor bu \u00e7al\u0131\u015fma; ancak di\u011fer havzalardaki b\u00fcy\u00fck trendleri kestiremiyor (1983\u2019ten bu yana). Fakat, Webster ve di\u011ferleri (2006) ile dolays\u0131z bir mukayese m\u00fcmk\u00fcn de\u011fil \u00e7\u00fcnk\u00fc onlar\u0131n verileri 1970\u2019de ba\u015fl\u0131yor. Ayr\u0131ca yeni analizin k\u0131sa s\u00fcreli olu\u015fu (sadece 23 y\u0131l), El Nino\u2019ya ba\u011flanan senelik veya ony\u0131ll\u0131k de\u011fi\u015fkenli\u011fi<\/a> vurguluyor. Yani, Kossin ve di\u011ferlerinin \u00e7al\u0131\u015fmas\u0131 olas\u0131 k\u00fcresel \u0131s\u0131nma ile kas\u0131rga yo\u011funlu\u011fu<\/a> aras\u0131ndaki ili\u015fkiyle ilgili fazla bir yeni bilgi sunam\u0131yor. <\/p>\n

\u00d6zet olarak, makaleleri ve yorumlar\u0131 okuyun, ama her yaz\u0131lana inanmay\u0131n.
\n<\/lang_tk>
\n<\/p>\n

O grande problema com a maior parte das discuss\u00f5es sobre tend\u00eancias na atividade dos furac\u00f5es<\/a> \u00e9 que os conjuntos de dados que todos est\u00e3o utilizando s\u00e3o conhecidos por n\u00e3o serem homog\u00eaneos devido a mudan\u00e7as nos procedimentos de observa\u00e7\u00e3o e na tecnologia ao longo dos anos. Assim, n\u00e3o \u00e9 surpreendente que uma nova re-an\u00e1lise (Kossin et al<\/a>, publicado em 28\/02\/2007) gerou um significativo interesse e controv\u00e9rsia no seio da comunidade de pesquisadores de furac\u00f5es (veja, por exemplo, Prometheus<\/a> ou Chris Mooney<\/a>). No entanto, ao inv\u00e9s de tomar este estudo por aquilo que ele \u00e9 \u2013 uma tentativa preliminar e \u00fatil de tornar homog\u00eanea uma parte dos dados (1983 a 2005) \u2013 ele est\u00e1 sendo tratado como se fosse a \u00faltima e definitiva palavra sobre o assunto. N\u00f3s freq\u00fcentemente afirmamos<\/a> que trabalhos isolados n\u00e3o s\u00e3o em geral os grandes avan\u00e7os (\u201cbreakthroughs\u201d) sugeridos pela imprensa ou pelos s\u00edtios de coment\u00e1rios, e este caso \u00e9 um bom exemplo.<\/p>\n

Kossin et al desenvolvem um algoritmo baseado em dados do Atl\u00e2ntico Norte que podem teoricamente ser utilizados com os dados de menor resolu\u00e7\u00e3o do in\u00edcio das s\u00e9ries hist\u00f3ricas e de regi\u00f5es mais remotas. Enquanto esta t\u00e9cnica funciona bem no Atl\u00e2ntico Norte (detectando quase todas as tempestades observadas no dado padr\u00e3o), ela n\u00e3o funciona t\u00e3o bem em outras regi\u00f5es \u2013 possivelmente porque as caracter\u00edsticas dos ciclones tropicais n\u00e3o s\u00e3o universais, ou porque a resolu\u00e7\u00e3o dos dados iniciais de sensoriamento remoto ainda \u00e9 insuficiente. O pior desempenho em outras regi\u00f5es \u00e9 certamente uma raz\u00e3o para antecipar que mais trabalho ser\u00e1 necess\u00e1rio para refinar estas estimativas, e deveria servir como um sinal de alerta para aqueles buscando conclus\u00f5es definitivas.\n<\/p>\n

Como esta pesquisa se encaixa com alguns dos trabalhos precedentes<\/a>? Bem, ela confirma a forte tend\u00eancia de aumento no Atl\u00e2ntico Norte (visto em Emanuel, 2005), mas n\u00e3o mostra tend\u00eancias significativas em outras regi\u00f5es (desde 1983). Este resultado n\u00e3o pode, entretanto, ser diretamente comparado com os de Webster et al (2005), uma vez que suas tend\u00eancias come\u00e7am nos anos 1970, e a brevidade da nova re-an\u00e1lise (somente 23 anos) enfatiza a variabilidade interanual e decadal<\/a> associada ao El Ni\u00f1o, por exemplo. Ent\u00e3o, \u00e9 improv\u00e1vel que o estudo de Kossin et al venha a esclarecer muito sobre a liga\u00e7\u00e3o potencial entre aquecimento global e a intensidade dos furac\u00f5es<\/a>. <\/p>\n

Em resumo, leia os trabalhos e coment\u00e1rios mas n\u00e3o acredite no oba-oba. <\/p>\n

traduzido por Fernando M. Ramos e Ivan B. T. Lima<\/a> <\/small><\/p>\n<\/p>\n

<\/lang_po>
\n
\nTraduit par Etienne Pesnelle<\/small><\/p>\n

Le gros probl\u00e8me dans la plupart des d\u00e9bats concernant les \u00e9volutions de l’activit\u00e9 cyclonique<\/a>, c’est que les bases de donn\u00e9es avec lesquelles tout le monde travaille ont notoirement des non-homog\u00e9n\u00e9it\u00e9s significatives, dues aux changements dans les pratiques et les techniques d’observations survenus au fil des ans. Il n’est donc pas surprenant qu’une nouvelle r\u00e9-analyse (Kossin et al<\/a>, publi\u00e9 hier) ait provoqu\u00e9 un int\u00e9r\u00eat marqu\u00e9 et une controverse au sein de la communaut\u00e9 de recherche cyclonique (voir ainsi Promotheus<\/a> ou Chris Mooney<\/a>). Cependant, plut\u00f4t que de prendre cette \u00e9tude pour ce qu’elle est \u2013 une tentative pr\u00e9alable et utile d’homog\u00e9n\u00e9iser une partie des donn\u00e9es (1983-2005) \u2013 on la traite malheureusement comme s’il s’agissait du
\nmot de la fin. Nous avons souvent fait remarquer<\/a> que les articles isol\u00e9s ne sont pas les perc\u00e9es que laissent parfois supposer les communiqu\u00e9s de presses ou les sites de discussion, et ce cas en est un bon exemple.<\/p>\n

Kossin et al ont d\u00e9velopp\u00e9 un algorithme, fond\u00e9 sur les donn\u00e9es nord-atlantiques, qui peut \u00eatre th\u00e9oriquement appliqu\u00e9 aux donn\u00e9es les plus grossi\u00e8res disponibles dans le pass\u00e9 le plus lointain et concernant des r\u00e9gions plus \u00e9loign\u00e9es. Alors que la technique marche bien sur l’Atlantique du Nord (recueillant pratiquement toutes les temp\u00eates trouv\u00e9es dans les donn\u00e9es standards), elle ne fonctionne pas aussi bien sur d’autres bassins \u2013 peut-\u00eatre parce que les caract\u00e9ristiques des cyclones tropicaux ne sont pas universels, ou parce qu’il n’y a pas assez de mesures grossi\u00e8res de t\u00e9l\u00e9d\u00e9tection disponibles dans le pass\u00e9. La moindre performance de l’algorithme dans les autres bassins est certainement une bonne raison pour penser que des travaux compl\u00e9mentaires seront n\u00e9cessaires pour affiner ces estimations, et devrait servir d’avertissement \u00e0 ceux qui veulent des
\nconclusions d\u00e9finitives.<\/p>\n

Comment cela s’articule-t-il avec une partie des travaux pr\u00e9c\u00e9dents<\/a> ? H\u00e9 bien, cela confirme l’\u00e9volution de tendance importante en Atlantique Nord (vue par Emanuel en 2005), mais ne montre pas d’\u00e9volution de tendance significative dans les autres bassins (depuis 1983). Cela n’est toutefois pas directement comparable \u00e0 Webster et al (2005) puisque leurs \u00e9volutions de tendance commencent dans les ann\u00e9es 1970, et la courte dur\u00e9e (23 ans seulement) de leur r\u00e9-analyse souligne la variabilit\u00e9 inter-annuelle et d\u00e9cennale<\/a> qui est associ\u00e9e \u00e0 El Ni\u00f1o par exemple. Il est donc assez improbable que l’\u00e9tude de Kossin et al puisse \u00e9clairer quelque peu le lien potentiel entre r\u00e9chauffement climatique et intensit\u00e9 des ouragans<\/a>.<\/p>\n

En r\u00e9sum\u00e9, lisez l’article et les commentaires mais ne prenez pas le battage m\u00e9diatique pour argent comptant.<\/lang_fr><\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

The big problem with much of the discussions about trends in hurricane activity is that the databases that everyone is working from are known to have significant inhomogeneities due to changes in observing practice and technology over the years. So it’s not surprising that a new re-analysis (Kossin et al, published yesterday) has been generating […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[1,21],"tags":[],"class_list":{"0":"post-413","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-climate-science","7":"category-hurricanes","8":"entry"},"aioseo_notices":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/413","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/comments?post=413"}],"version-history":[{"count":0,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/413\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/media?parent=413"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/categories?post=413"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/tags?post=413"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}