Tamino’s Folly - Temperatures did drop this past decade

“Tamino” has made a couple of posts on how the last 10 year drop in temperature is not statistically significant, so it isn’t real. He went too far in his last one and began claiming it was a tactic of some kind of creature called a denialist to confuse and confound the public.

Let’s see what Tamino has been saying on his blog link HERE.

Some of you might wonder why I make so many posts about the impact of noise on trend analysis, and how it can not only lead to mistaken conclusions about temperature trends, it can be abused by those who wish deliberately to mislead readers. The reason is that this is still a common tactic by denialists to confuse and confound the public.

I just hate bad science. First he points out how Bjorn Lomborg made some comments about temperature decreasing, after placing the ever more popular label of denialist on him implying Lomborg’s statements were intended to confound and confuse the public. Heres the main point of what Bjorn Lomborg said.

They (temperatures) have actually decreased by between 0.01 and 0.1C per decade.

Ok, so graphs like the one below are the reason Bjorn Lomborg is a denialist.

I copied this graph from Digital Diatribes of a Random Idiot - A great unbiased site for trends (link on the right). Note the slope of -.0082 (.01C/month units or .00098 degC/year - Thanks to digitial diatribes comment below) in the equation on the graph. Most of us know this is actual data and is correct, in fact every measure is showing similar results. The earth stopped warming- a very inconvenient truth. So Tamino what’s the argument, why are the evil and uncooperative denialists wrong?

Statistics of course.

Here comes the numbers from Tamino.

The most natural meaning of “this decade” is — well, this decade, i.e., the 2000’s. So I computed the trend and its uncertainty (in deg.C/decade) for three data sets: NASA GISS, RSS TLT, and UAH TLT, using data from 2000 to the present. To estimate the uncertainties, I modelled the noise as an ARMA(1,1) process. Here are the results:

Data	Rate (deg.C/decade)	Uncertainty (2-sigma)
GISS	+0.11	0.28
RSS	+0.03	0.40
UAH	+0.05	0.42

All three of these show warming during “this decade,” although for none of them is the result statistically significant.

Ok Tamino has calculated GISS, RSS and UAH. One ground measurement and two satellite. For those of you who don’t spend their afternoons and weekends digging into this. ARMA is a fancy sounding method for what ends up being a simple process Tamino has used to estimate the standard deviation of the temperature. Sometimes it seems the global warming guys believe the more complicated the better, but no matter. He has a 2 sigma column which represents about 95%. He then goes on to say that because of the sigma 0.28 or 0.40 is bigger than the trend, the trend is not statistically significant. He repeats the comment below.

Let’s make the same calculation using data from January 1998 to the present:

Data	Rate (deg.C/decade)	Uncertainty (2-sigma)
GISS	+0.10	0.22
RSS	-0.07	0.38
UAH	-0.05	0.38

Finally one can obtain negative trend rates, but only for 2 of the 3 data sets. But again, none of the results is statistically significant. Even allowing this dreadfully dishonest cherry-picked start date, the most favorable

Now Tamino claims to be a statistician so I can’t see how he made such a simple boneheaded error but if he wants to pitch softballs, I’ll hit em. Just to make sure he’s in good and deep here’s one more quote.

I’ve previously said “Those who point to 10-year “trends,” or 7-year “trends,” to claim that global warming has come to a halt, or even slowed, are fooling themselves.” I may have been mistaken; is Lomborg fooling himself, or does he know exactly what he’s doing?

So, Mr. Lomborg, we’re all very curious: how did you get those numbers?

Wrong turns everywhere

The first and really obvious error Tamino makes is referring to the short term variation in temperature as noise. Noise in the context of sigma is related to measurement error. How can we determine the measurement error of the three methods GISS, RSS and UAH. Well the graph of the three is below.

The first thing you notice from this graph is that the 3 measurements track each other pretty well. The signal is therefore not completely noise. Well what is the level of noise? We have above 12 measurements per year times 29 years. So we don’t need ARMA or other BS we can simply subtract the data. I put the numbers in a spreadsheet and calculated the difference between RSS and GISS, RSS and UAH and UAH and GISS. With 348 measurments for each type of instrument I was able to get a very good estimate of standard deviation of the actual measurements. Again, no ARMA, just using the difference between the graphs.

GISS - RSS one sigma 0.099 Two sigma 0.198

RSS-UAH one sigma 0.101 Two sigma 0.202

GISS-UAH one sigma 0.058 Two sigma 0.116

These are actual numbers and are substantially lower than the estimated two sigma by Tamino but still bigger than the 0.1 C per decade although the two sigma GISS - UAH is within a 90% confidence interval already!

This isn’t the end though. Tamino ended his discussion there implying shenanigans and other things of those who see a trend.

Both of our standard deviation calcs are for a SINGLE measurement NOT a trend.

This is a big screw up. How can a self proclaimed statistical expert miss this, it’s beyond me. Anyway, none of us is universally right every day but most hold their tongue rather than post a big boner on the internet. Well most scientists realize that when you take more than one measurement of a value you improve the accuracy. So being a non-genius, I used R to calculate what the statistical certainty of the slope is when taken over 10 year trends. Thanks again to Steve McIntyre for pointing me to this software. I don’t love it but it is convenient.

t=read.csv(”c:/agw/giss data/10 year variation.csv”, header=FALSE)

x = (1:length(t[,1]))

y=t[,1]

a=gls(y ~x)
confint(a)

confint(a)[2,1]-confint(a)[2,2]

y=t[,2]

a=gls(y ~x)
confint(a)
confint(a)[2,1]-confint(a)[2,2]

y=t[,3]

a=gls(y ~x)
confint(a)
confint(a)[2,1]-confint(a)[2,2]

What this script does is load the difference files i.e. GISS-UAH, fits a line to them and presents a number for the statistical confidence interval of the slope coefficient at 95 percent confidence which is about two sigma. The confidence of the slope of the trend is as follows

GISS - RSS Two sigma 0.00108 DegC/year

RSS-UAH Two sigma 0.001068 DegC/year

GISS-UAH Two sigma 0.0005154 DegC/year

Despite a standard deviation of .02 We have a twenty times more accurate slope measurement of 0.001degC/year !

Conclusions

1. We can say with a high degree of certainty that we know the trend of temperature for any ten year plot to within .01 degC/decade.

2. We can say that temperatures have dropped this past decade, just as our eyes looking at the graphs had already told us.

3. We can also say that Tamino owes a few more apologies.

He and Real Climate still don’t let me post on their blogs!

I wonder why?

.y 0,02 en los veranos

Monday, October 20, 2008

..y 0,02 en los veranos

Siguiendo con el post anterior, pongo los mapas de verano (meses de junio, julio y agosto). El cambio de la temperatura media global en lo que va de siglo, 2001-2008, da un resultado según el GISS de 0,02 ºC. Qué pena, dos centésimas de grado en ocho años ....

Solamente destaca un calentón en el Mar de Ross, en la Antártida, en donde precisamente no abundan las mediciones

Por lo demás, es curioso que en más de la mitad del Mediterráneo, la occidental, se ha manifestado en ese período una leve tendencia al enfriamiento. Lo contrario del sermón casi cotidiano que por estos lares soportar habemus.

Sunday, October 19, 2008

Así va el siglo: 0,00

Pongo aquí dos mapas (azimutales, equivalentes, centrados en el ecuador, uno en 0º de longitud y el otro en 180º) que representan el cambio de temperatura (según los extremos de la tendencia lineal) en los inviernos que van del 2001 al 2008 (meses de diciembre, enero y febrero). Al final, a pesar de las sesudas discusiones, no me aclaré si el siglo XXI empezó en el año 2000 o en el 2001. Me parece, por lo que voy viendo, que a pesar del adelanto de las celebraciones, se considera que comenzó en el 2001. Da igual.

Los mapas los construyo gracias a los datos de la página web del Instituto Goddard de la NASA, dirigido por el calentista oficial James Hansen (abajo explicaré el procedimiento). Qué rabia le tiene que dar al jefe que llevemos ya casi ocho años de siglo y el cálculo del cambio medio de la temperatura global en este período da un resultado para el invierno de 0,00.

En tonos cálidos, amarillos y naranjas, aparecen las zonas en las que ha habido calentamiento. Destaca especialmente la zona del Artico al norte de Siberia. En tonos fríos, azules, aparecen las zonas de enfriamiento. Destaca especialmente Alaska. Por lo demás, se notan pocos cambios. Y el CO2, por supuesto, ha seguido subiendo por igual en todas partes. Otro día pondré los mapas de verano.

ref. GISS
para construir los mapas, primero hay que bajarse el programa NASA GISS: Panoply netCDF Viewer, segundo hay que construir el mapa (trends, 2001-2008, invierno, con mar incluído) entrando en los mapas del GISS, y descargarlo en donde pone (abajo) netCDF. Finalmente abrirlo con Panoply y elegir la escala y proyección cartográfica que se quiera.
Es divertido.

Sun’s magnetic field still in a funk during September

Sun’s magnetic field still in a funk during September

11 10 2008

While the sun puts out a new and significant cycle 24 spot, the real news is just how quiet the suns magnetic field has been in the past couple of years, and remained during September 2008. From the data provided by NOAA’s Space Weather Prediction Center (SWPC) you can see just how little magnetic field activity there has been. I’ve graphed it below with the latest available data from October 6th, 2008:

click for a larger image

What I find most interesting about the Geomagnetic Average Planetary Index graph above is what happened around October 2005. Notice the sharp drop in the magnetic index and the continuance at low levels.

This looks much like a “step function” that I see on GISS surface temperature graphs when a station has been relocated to a cooler measurement environment. In the case of the sun, it appears this indicates that something abruptly “switched off” in the inner workings of the solar dynamo. Note that in the prior months, the magnetic index was ramping up a bit with more activity, then it simply dropped and stayed mostly flat.

Currently the Ap magnetic index continues at a low level, and while the “smoothed” data from SWPC is not made available for 2008, I’ve added it with a dashed blue line, and the trend appears to be going down.

However, it will be interesting to see if an uptick in the Ap index occurs, now that a significant SC24 spot has emerged. Unfortunately, we’ll have to wait until early November for SWPC to update the data set.

Boise gets earliest snow on record, record cold in Oregon, Washington

Boise gets earliest snow on record, record cold in Oregon, Washington

12 10 2008

From the Idaho Statesman:

Valley shivers as winter weather makes a premature appearance

Big snow flakes fell early Friday evening, turning Downtown Boise into a giant snow globe for people on their way home from work.

The snow caught many people off guard, including this bicyclist heading down Idaho Street between 8th and 9th around 5:45 p.m. Across the Treasure Valley, tree branches heavy with wet, snow-covered leaves fell on power lines, causing scattered power outages.

This is the earliest measurable snowfall in Boise since recordkeeping began in 1898, according to the National Weather Service. At 10 p.m., the Weather Service said 1.7 inches of snow had fallen. The previous earliest recorded snowfall was Oct. 12, 1969, when a little more than an inch fell. And if the snow wasn’t enough, meteorologists say winds across southwestern Idaho will average 25 to 40 mph through Saturday afternoon, with gusts up to 55 mph. Sustained winds of 30 to 40 mph are expected, which can make driving difficult.

---

There is also some early and record snows in Billings Montana

A snowfall record for Oct. 11 was set in Billings yesterday.
According the National Weather Service, Billings saw 3.1 inches of snow Friday. The old record of 2.8 inches was set in 1969.

BOB ZELLAR/Gazette Staff

Vehicles drive through the snow and slush Highway 3 between Zimmerman Trail and the airport Friday October 10, 2008.

---

Here in Northern California, we are getting some much earlier than normal cold weather. As you can see on my Bidwell Ranch Weather Station, we got into the 30’s last night, not a record, but darned early for fall weather here:

Ice Reality Check: Arctic Ice Now 31.3% Over Last Year

Ice Reality Check: Arctic Ice Now 31.3% Over Last Year, plus Scientists Counter Latest Arctic ‘Record’ Warmth Claims as ‘Pseudoscience’

18 10 2008

10/17/2007 5,663,125 square kilometers

10/17/2008 7,436,406 square kilometers

Δice = 1,773,281 sqkm or 31.3% more than last year

Source data here: http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv (Excel file)

You’ve probably heard by now how this new story circulating this week claims “record warmth” and that we are in the peak time of melting. Meanwhile, “back at the ranch”, sea ice extent continues a steady upward climb as shown above.

Scientists Counter Latest Arctic ‘Record’ Warmth Claims as ‘Pseudoscience’ - Comprehensive Arctic Data Round Up - October 17, 2008

Claim: Newspaper article claims Arctic Temps Peak in November - Claims Arctic offers ‘early warning signs’ - McClatchy Newspapers - October 16, 2008

Excerpt: Temperatures in the Arctic last fall hit an all-time high - more than 9 degrees Fahrenheit (5 degrees Centigrade) above normal - and remain almost as high this year, an international team of scientists reported Thursday. “The year 2007 was the warmest year on record in the Arctic,” said Jackie Richter-Menge, a climate expert at the Cold Regions Research and Engineering Laboratory in Hanover, N.H, and editor of the latest annual Arctic Report Card. “These are dynamic and dramatic times in the Arctic,” she said. “The outlook isn’t good.” Arctic temperatures naturally peak in October and November, after sea ice shrinks during the summer. [...] Scientists say these changes in the Arctic are early warning signs of what may be coming for the rest of the world’s climate.

Arctic Reality Check: Why isn’t the cooling Antarctic considered ‘an indicator of what might happen to the rest of the world?’

By Climate Scientist Dr. Ben Herman, past director of the Institute of Atmospheric Physics and former Head of the Department of Atmospheric Sciences at the University of Arizona is a member of both the Institute for the Study of Planet Earth’s Executive Committee and the Committee on Global Change.

Read the rest of this entry »

Comments : 20 Comments »

Categories : Science, sea ice

---

Can Oyster Art Curb Global Warming?

17 10 2008

by John Goetz

Here is an fun press release I ran across on prweb.com. If Ms. Haseltine is successful in her project, we might see more local produce on the Grand Central Station Oyster Bar menu. But will it actually do anything about global warming?

Professor Uses Oysters to Teach College Students to Curb Global Warming

Crassotrea virginica

Internationally acclaimed environmental artist Mara G Haseltine joined NYC’s The New School for Liberal Arts to teach, Oyster Gardens, the only class of its kind worldwide where the students will focus on the design and planning of a floating oyster colony, an innovative public art project which merges art, sustainable design and field science.

New York, NY (PRWEB) October 16, 2008 — Internationally acclaimed environmental artist Mara G Haseltine joined NYC’s The New School for Liberal Arts to teach Oyster Gardens, the only class of its kind worldwide where the students will focus on the design and planning of a floating oyster colony, an innovative public art project which merges art, sustainable design and field science.

Oyster Gardens celebrates New York’s past as the oyster capital of the world boasting of 350 square miles of bio diverse oyster reef as well as to prepare it for a sustainable future with a bountiful biodiverse estuary. Students learn about the history and the biology of the Crassostrea Virginia, the indigenous oyster of New York, as well as traditional and new innovative methods of reef restoration. In this unique course students work hand in hand with a cross disciplinary team that includes marine engineers, marine biologists, along with conservation organizations to plan and design and a ‘moveable reef’ — a floating oyster colony that could be deployed around the harbor.

The idea is to bring back Crassotrea Virginica to New York, which would create a natural filtration system that cleans the waters and simultaneously brings back biodiversity, that has been missing in New York’s waters and estuaries since the Industrial Revolution. Oysters are the backbone of the benthic habitat and can act as natural water treatment plants. The average oyster filters 5-25 gallons of “nutrient” rich water per day. The restoration of 100 square miles of reef would filter twenty seven billion tons of wastewater that flows into New York’s waterways annually. The reef would not only be a haven for oyster,s but would quickly become a diverse habitat for aquatic life of all forms, from gastropods to stripped bass.

co2 Sunday, October 12, 2008 Agujero de ozono, temporada 2008

Hace más de veinte años, en 1987, se firmó el Protocolo de Montreal con el objetivo de rellenar el agujero de ozono de la Antártida, que, según la teoría oficial, se había formado debido a los CFC's usados como refrigerantes. Se prohibieron los CFC's. Pero el "agujero de ozono" sigue formándose hoy igual que antes.

Por agujero de ozono se entiende la zona en donde temporalmente, de septiembre a diciembre, el espesor de ozono sobre la Antártida se reduce y queda por debajo de las 220 unidades Dobson (100 unidades Dobson equivalen a 1 mm de espesor de ozono). Lo expliqué de forma más detallada el año pasado (Agujero de ozono, temporada 2007). La media anual de ozono sobre la Antártida es mayor que sobre la zona tropical.



La reducción que ocurre entre septiembre y diciembre responde a complicadas causas de orden físico (movimientos atmósfericos con transporte de ozono) y de orden químico (reacciones fotoquímicas de creación y destrucción de ozono). El nefasto simplismo ecologista redujo toda la "culpabilidad" a los CFC's , como ahora se reduce toda la "culpabilidad" del cambio climático al CO2.
El tema del ozono es un tema sobre el que los medios prefieren pasar de puntilllas, debido a que el propio IPCC reconoce que una supuesta disminución del ozono estratosférico contribuiría al enfriamiento de la troposfera o, por lo menos, a la amortiguación del temido calentamiento. En fin, lo contrario de lo que durante décadas han estado escribiendo, retransmitiendo y hasta televisando. Es cierto que un aumento del CO2, precisamente porque enfría la baja estratosfera puede contribuir a reforzar el aislamiento del aire encerrado en el vórtice polar y contribuir a una mayor reducción de ozono. Pero en este caso, no sería el cloro de los CFC's el principal "culpable", lo cual tampoco concuerda con lo que se firmó en Montreal y nos repitieron hasta la saciedad.

Speck spotted - looks to be cycle 23

Not much time for a full report, as it is very late for me, but I’ll pass this along from comments. Looks to be cycle 23 due to low latitude. - Anthony

Looks like a sunspot has appeared recently, as of Oct 9, 1600. Magnetogram also shows a spot. Is this the last spot that had blinked in and out?

http://sohowww.nascom.nasa.gov/data/realtime/mdi_igr/1024/latest.html

Kids Against Anthropongenic Global Warming

There’s been some discussion about the “indoctrination” of AGW theory in school systems worldwide, mostly by teachers showing Al Gore’s movie, An Inconvenient Truth, in schools.

As a former school trustee in my town of Chico, CA, I can vouch for the fact that AIT has been shown in some local schools, with student discussions centered around it. It is of course not on the approved curriculum, but some teachers take it upon themselves to introduce it into the classroom on their own. Since most teachers have leeway in choosing films to show to classes, unlike with textbooks, which are chosen by the school board, films generally “fly under the radar” requiring only a form approved by the school principal.

So it was with interest that I was advised of a new website, Kids Against Anthropongenic Global Warming, put together by 14 year old girl from Far North Queensland, Australia. I see it as an antithesis to the horrible website that was put together by Australia’s ABC TV network:

TV Network Tells Kids How Long Their Carbon Footprint Should Allow Them to Live

I’ve never seen a more disgusting kid-theme for “science” education than the above link.

Neve e gran freddo sulle montagne bulgare

Sul Vitosha, la montagna di Sofia, decine di turisti bloccati dalla tormenta domenica. -11°C la minima al Mussala lunedì. Piogge abbondanti lunedì in Belgio e Germania. Caldo in Spagna (Cordoba 29°C) e Turchia (Urfa 30°C). 43°C a Curtin, nord dell'Australia Occidentale. Ultime gelate in Nuova Zelanda.

---

---

Un'immagine della tormenta di neve di domenica 5 ottobre sul Monte Vitosha. Fonte www.novinite.com

---

Giovanni Staiano: 07-10-2008 ore 08:03

Lunedì residue precipitazioni in Bulgaria, dopo quelle abbondanti di domenica, ma soprattutto molto freddo. Tra le 18 GMT di domenica e la stessa ora di lunedì, 14 mm a Lovtech, che si agiungono ai 68 delle 24 ore precedenti. In montagna, come detto, gran freddo. Sul Mussala (m 2962), -10,6°C la temperatura minima, mentre è scesa fino a -6,8°C Cherni Vrah (m 2286), la vetta più alta del Monte Vitosha. Le nevicate di domenica hanno sorpreso decine di turisti, che sono rimasti bloccati dalla tormenta (20 cm caduti in poche ore) sul Monte Vitosha, nei pressi della capitale Sofia. Alberi e linee elettriche sono infatti caduti, sotto il peso della neve, complice anche il forte vento, sulle strade dell'area montana, impedendo il transito dei veicoli. Il Monte Vitosha dista solo 25-30 minuti di macchina dalla capitale bulgara ed è quindi una frequentata meta di svago, in particolare nei fine settimana.

Abbondanti precipitazioni lunedì in Belgio e Germania. Tra le 18 GMT di domenica e la stessa ora di lunedì, in Belgio 57 mm a Ernage, 34 a Elsenborn, 29 a Mont-Rigi. Nelle stesse 24 ore, in Germania, 79 mm a Schmuecke, 41 a Wasserkuppe, 37 a Grosser Arber, 31 a Bad Marienberg.

Lunedì 6 ottobre il caldo si è fatto sentire in gran parte della Spagna. Queste alcune massime: Cordoba 28,5°C, Badajoz e Murcia 28,0°C, Saragozza 27,4°C, Jerez 27,2°C.

In gran parte della Turchia anche lunedì 6 ottobre è stata una giornata calda. Queste alcune massime: Urfa 30,0°C, Adana e Diyarbakir 28,9°C, Finike 28,7°C, Iskenderun 28,2°C, Malatya 28,0°C, Siirt 27,8°C, Konya 27,0°C. Le medie delle massime di ottobre sono le seguenti: Urfa 26,3°C, Diyarbakir 24,9°C, Siirt 24,1°C, Malatya 20,9°C, Konya 19,6°C.

Nel nord dell'Australia fa molto caldo in questi giorni. Lunedì pomeriggio, nella parte nord dell'Australia Occidentale, Curtin, Fitzroy Crossing e West Roebuck hanno toccato rispettivamente i 42,7°, 41,8° e 41,7°C. 39,3°C la media delle massime di ottobre a Fitzroy Crossing. Molto caldo anche nei Territori del Nord, dove Tennant Creek ha toccato i 39,9°C ed Alice Springs i 38,0°C, rispettivamente 5,2° e 7,1°C al di sopra delle medie delle massime di ottobre.

Nell'Isola del Sud della Nuova Zelanda, gelate tardive si sono registrate lunedì 6 ottobre, con minime -0.8°C a Dunedin e -0,6°C a Timaru. Le medie delle minime di ottobre sono 7,2° e 4,9°C.

Una forte tempesta di vento ha interessato, in Antartide, parte della Princess Martha Coast tra sabato sera e lunedì mattina. Domenica, al culmine della tempesta, il vento sostenuto ha soffiato per diverse ore tra i 110 e i 120 km/h.

Il freddo in Sudamerica ha pochi precedenti nel passato

Le temperature sotto lo zero in Uruguay, in Ottobre, sono rarissime, con pochi precedenti negli ultimi trent'anni.

---

---

www.cdc.noaa.gov: il freddo permane sul Brasile centro meridionale e l'Uruguay, mentre temperature più miti interessano la parte meridionale dell'Argentina.

---

Marco Rossi: 10-10-2008 ore 09:40

Abbiamo già parlato in più di un'occasione delle basse temperature che si sono verificate in Sudamerica dai primi di Settembre a questa parte, con una ripetuta serie di ondate di freddo che normalmente non si verificano in quella che è la Primavera dell'Emisfero Meridionale.

L'ultima, verificatasi lo scorso 09 Ottobre, grazie alla creazione del ben noto blocco anticiclonico sulle coste cilene (condizione che favorisce le irruzioni fredde meridionali sull'Argentina e sull'Uruguay), è stata una delle più intense, provocando temperature minime di -3,0°C agli aeroporti argentini di Tandil, e di Mar della Plata, -1,5°C all'aeroporto uruguayano di Florida, e di +1,7°C sulla Brasiliana Bage, a soli 242 metri di altezza.

La genesi delle invasioni d'aria fredda su queste zone rimane la medesima: dapprima la formazione di un blocco anticiclonico sul Pacifico, al largo delle coste cilene, favorisce la penetrazione di una depressione di lontana origine antartica verso latitudini settentrionali.

In seguito, tale depressione si allontana verso occidente, in Atlantico, mentre l'Anticiclone di blocco si sposta verso levante, favorendo, con il rasserenamento del cielo, temperature estremamente basse per irraggiamento.

Questo si verifica tipicamente durante la stagione invernale, ma è molto raro il caso di invasioni fredde fino al Brasile meridionale durante la Primavera avanzata.

La località di Florida, in Uruguay, ha presentato in questo mese di Ottobre due gelate, con valori di 0,0°C, e -1,5°C.

Dal 1995 ad oggi, anno di inizio delle rilevazioni, la temperatura più bassa mai rilevata in questo mese erano stati +0,0°C il 27 Ottobre del 2004.

0,0°C si erano toccati anche il 12 e 13 Ottobre del 2003, mentre negli altri anni non era mai gelato, né la temperatura era mai scesa fino a -1,5°C.

Sempre in Uruguay, la zona di Durazno ha toccato un minimo di -0,4°C il 09 Ottobre scorso.

Qui la temperatura più bassa mai raggiunta in Ottobre erano stati i -2,0°C del 04 Ottobre 1999, valore isolato ed un po' sospetto, visto che negli ultimi trent'anni, dal 1979 ad oggi, a Durazno non è mai gelato, il termometro non è mai sceso sotto lo zero in questo mese.

Questo a sottolineare, se non l'eccezionalità, almeno la rarità di questi eventi di ondate di freddo in pieno Ottobre.

---

Marco Rossi

---

© Meteogiornale