quarta-feira, novembro 19, 2008

O misterioso Outubro de 2008

O meteorologista brasileiro Eugenio Jaeckel Hackbart – referido várias vezes no MC – é um cientista sério. Como tal, temos a obrigação de ler os seus textos com a atenção que merece. É o que vamos fazer seguidamente com um artigo que publicou no blogue ICECAP e que transcrevemos com a devida vénia.

October’s Temperature Discrepencies

By Eugenio Hackbart, METSUL

I read all this week with great attention all the discussion regarding the temperature data from NASA’s GISS and other sources. If the exact dimension of the positive anomaly in Russia can be disputed, there is no doubt October was much warmer than average in that region. Russian press reported it was the warmest October on record in Moscow:

MOSCOW, November 1 (RIA Novosti) - October was the warmest on record in Moscow with an average temperature of over 9 degrees Celsius (48.2 degree Fahrenheit), the Russian meteorological website reported on Saturday. The previous record of 8.9 degree Celsius (48 degree Fahrenheit) was registered in October 1967. On the last day of October, the weather was unusually warm across many Russian regions, setting numerous records, including in the Moscow Region where temperatures reached 13.2 degree Celsius (55.8 degree Fahrenheit) and Russia's second largest city of St. Petersburg, where similar temperatures were recorded. The usual average temperature for October in Moscow is 4.3 degree Celsius (39.7 degree Fahrenheit). The coldest-ever October in Moscow was registered in 1976, with average temperature of -0.8 degree Celsius (30.6 degree Fahrenheit). Numerous temperature records have been broken in Moscow in recent years. January 2008 was the mildest since records began 130 years ago. 2007 was the warmest year in one and a half centuries for Russia.

October was also the warmest on record for Hong Kong in East Asia with the highest average for the tenth month of the year since 1884:

Last month was the warmest October since records began in 1884, with a monthly mean temperature of 26.5 degrees Celsius, 0.1 degree higher than the 26.4 degrees recorded in 1983 and 2006. The Hong Kong Observatory said the northeast monsoon during the month was weak, resulting in cooler air failing to reach the south China coastal areas. The 1971-2000 climatological record shows there are on average about six days with a minimum temperature of below 22 degrees in October. However, not a single day this October was below 22 degrees. The record-breaking temperature also reflects to a certain extent the long-term warming trend in Hong Kong, the observatory said. The monthly mean October temperatures in the past 50 years showed a rising trend of about 0.2 degree each decade and half of the 10 warmest Octobers occurred in the past decade.

The October global temperature discussions once more reveal how unreliable all these metrics are. In fact, I suggest the reading of a very interesting post I read this week at Climate Skeptic exactly on this matter.

I tell my listeners and reader over here in Southern Brazil that October was near average globally (UAH data), but in the next day there is a report on the papers and on television that the month was the warmest on record on Earth. Of course, the average listener and reader start to question where my first information was correct. NASA is contracting the
information from the day before. Try to tell people that the agency that has sent the man to the moon cannot measure the temperature on Earth correctly and you get a credibility problem with regular people. But the readers of ICECAP are not regular people and they know NASA, in fact, had some serious problems.

Every month, I take a look at these global maps not only to track the planet trend, but also to compare with my local reality. It is common to see very important discrepancies. I believe much of you do the same and have reached the same conclusion. If Steve McIntyre was surprised to see the warmer than average October in Toronto, I can say the same on Rio Grande do Sul. Both GISS and Met Office data for last month indicated a warmer than average October in Rio Grande do Sul, the southernmost state of Brazil where I live. Take a look at the circles in the maps: (vide mapas no original, sff).

In fact, October was not 1C warmer than average here. It was very close to the average with some minor positive or negative deviations, depending on the station. It was a very wet month with a cold start. Both conditions prevented a large positive anomaly as depicted by GISS and the Met Office. For this matter, take a look at the maps for October in Brazil with the anomalies for low temperature (minima) and high (maxima). The maps were generated early this month by the officials Brazilian weather bureaus: Cptec and Inmet.

Temperature in the metropolitan area of Porto Alegre (4 million people) was 0.1 below average last month, but the same area appears in the map as above average. The truth it was a mild and comfortable October over here with few very warm days. I am sure the same discrepancies with local reality can be found in many other areas in the world. For that and other reasons, I still believe UAH and RSS are much more reliable. At least they do not have almost the entire African continent in gray.

Dos mapas que Eugenio Hackbart apresenta no seu artigo, salientamos o da Fig. 139. Este mapa é elucidativo. Além das críticas pertinentes do autor do artigo acabado de transcrever, esta figura merece mais algumas reflexões.

Passando por cima das dúvidas acerca da informação fornecida por James E. Hansen (vide post anterior), a Fig. 139 levanta muitas mais dúvidas.

Assim, parece estranho que o dióxido de carbono tenha atacado a Sibéria e deixado em paz a Península Ibérica? Mas que efeito tão esquisito é este que não se distribui homogeneamente pelo Globo?

Sem ter conhecimento das cartas sinópticas da Sibéria não é possível tirar quaisquer conclusões do que aconteceu nesta região. A pesquisa efectuada na net não permitiu obter a informação desejada.

No entanto, a Universidade do Reno permite-nos analisar as cartas sinópticas da região de Moscovo. Deste modo, entre 1 e 31 de Outubro de 2008, as temperaturas de Moscovo foram sucessivamente (em ºC, às 12 horas UTC, a 2 metros do solo):

12, 12, 14, 16, 15, 15, 11, 11, 5, 6, 7, 8, 10, 8, 9, 9, 8, 8, 6, 6, 7, 9, 7, 5, 5, 5, 7, 5, 7, 8, 9.

Mas, o que muito é importante, as pressões atmosféricas situaram-se quase sempre nos valores elevados de 1020 hPa (hectopascais), com um núcleo H (high, alta pressão em inglês) a rondar a região de Moscovo. A excepção foi a menor pressão dos 1000 hPa a 1010 hPa de 17 e 18 de Outubro.

Está, pois, explicada a situação da região de Moscovo. Foram as altas pressões que se responsabilizaram por um Outubro agradabilíssimo para os moscovitas. Nada de anormal no reino dos czares. Os conhecidos anticiclones móveis polares aglutinaram-se perante o obstáculo do anticiclone siberiano.

Claro que os media já estão a explorar a situação no mau sentido. O USA Today é um exemplo característico. Repete-se a história do Verão quente de 2003 na Europa.