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Marcel Leroux no longer with us

by Luis de Sousa Thu Aug 14th, 2008 at 06:45:52 AM EST

It was with great sadness that I learnt this morning that Professor Marcel Leroux passed away two days ago in Marseille. The man that brought the concept of the Mobile Polar High into existence and made us consider atmospheric circulation in completely new terms is no longer between us.


Marcel Leroux's parents were originary from Bretagne but he was born in Tunisia, were he completed his first studies as a child. He would then move to France where he would become one of the country's best achieved scientists on the fields of Meteorology and Climatology, affiliated with the Université Jean-Moulin at Lyon.

His studies started by being cantered on his homeland, Africa, were he struggled to explain meterologic phenomena (as the Sahel droughts) with classic theory. By carefully examining satellite imagery he understood that the tri-cellular model was invalidated by the meridional movements described by large masses of cold air coming from the poles.

Those observations would lead him to the concept of the Mobile Polar High - giant masses of cold air that form in the poles and move towards the meteorologic equator, thus performing the energy transfers triggered by the temperature differential between the poles and the equator. Due to their cold temperatures and high pressure these masses of air travel close to the planet's surface and can easily get trapped by such things as the geographic edifices, accumulating into what Leroux called Anticyclonic Agglutinations (AA).

Beyond that he also understood that the Meriodinal Atmospheric Circulation occurs in different ways in time:

  • Fast Mode - occurs when the temperature differential between Poles and the Equator is higher. At an yearly scale this is the mode that takes place during winter, resulting in more violent weather events.


  • Slow Mode - occurs when the temperature differential between Poles and the Equator is lower. At an yearly scale this is what succeeds during the Summer with milder weather and fewer stroms.

At a decadal scale climate oscillations between these two modes are also observable, as is the case in the North Atlantic, where pressure patterns alternate between two modes (captured in the NAO index).

Atmospheric Circulation According to Marcel Leroux. The blue arrows represent the preferred pathways of the MPH, with the AA symbols representing their usual gathering places.

In later years Professor Leroux became a prominent critic of the theory of Anthropogenic induced Global Warming (AGW). He pointed out that the evolution of Climate since the 1970s shift (when the Pacific Decadal Oscillation went into its positive phase) wasn't fitting with a simple warming trend of the planet. Among other things, deserts were expanding instead of retreating, in many places there were clear increases in atmospheric pressure and precipitation wasn't increasing. Evidence pointed to an acceleration of Meridional Circulation and not just a warming of the Atmosphere.

After the turn of the century several weather events, not only gave credit to Professor Leroux findings but also increased the severity of his criticism of AGW theory. In the Summer of 2003 an AA covered Europe creating a heat wave with few parallels in history. The media largely attributed the event to AGW without caring much for pressure charts that clearly showed above normal pressures, a signature of the AA trapping the air heated at the surface.

Meteorologic chart from the 7th of August of 2003. An AA centred in the British Islands left much of the continent under pressures above 1018 hPa trapping hot air at the surface and producing a memorable heat wave.

During the winter of 2004/2005 there were clear signs of the increase in Circulation speed. By the first days of March an AA installed itself again over much of Europe; while there, low pressure fronts kept flowing form the Atlantic that once hit the AA where quickly forced upwards producing large volumes of snowfall. In less than a week the Continent was covered in white.

More recently the 2007 Summer heat wave that hit Hungary and Turkey and the cold snap that hit China in January of this year were also notable events vindicating Professor Leroux's theory. Both were again reported by the media as result of increased global temperatures, while a simple look at pressure charts from that time reveal that both were caused by AA.

I had very little contact with professor Leroux but I have the feeling that we has becoming a bitter man with all the misinformation the public was (and still is) getting on these phenomena that he first learnt and explained.

Earlier this year I inquired him on the hypothesis of the decadal circulation mode shitfs being triggered by changes in the planet's angular momentum. In his answer he wrote these words:

If you have read "Global Warming : myth or reality ?" you had seen that I observe the concrete meteorological "things" ... and I have not found any relation between CO2 and climate.

Among other publications the following are possibly the most referenced:

1993. The Mobile Polar High: a new concept explaining present mechanisms of meridional air-mass and energy exchanges and global propagation of palaeoclimatic changes. Global and Planetary Change 7: 69-93.

1998. Dynamic Analysis of Weather and Climate: Atmospheric Circulation, Perturbations, Climatic Evolution. Praxis, Chichester.

2002. The Meteorology and Climate of Tropical Africa. Springer Praxis.

2005. Global Warming - Myth Or Reality? The erring ways of climatology. Springer Praxis.

A good article for a first exposure on Meridional Circulation can be read here.

An article published by the magazine Fusion Revue in the Spring of 2003 (nº 95) called Réchauffement global: une imposture scientifique! is a good introduction to the contradictions of the AGW theory for the lay person. Unfortunately the magazine ceased to exist in 2006 and the article was withdrawn from the internet. Now only a portuguese translation exists online. Time permiting an English version may come to be.

A video interview with Professor Leroux can be watched here.


Lacking equal in English, I'll leave a compliment in my mother language:

Eterna saudade.

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thanks for the link.

The other day I found a beautifully little article by Andrew G. Marshall. In particular, i liked the simplicity of the following analysis: if you have two variables, A and B, a simultaneous increase in A and B does not mean that increase in A causes increase in B; two other possibilities must be considered - that increase in B causes increase A, or that a change in a third variable C may cause the increase of both A and B; let A be atmospheric concentration of greenhouse gases, B   atmospheric average temperatures, C solar output.

by findmeaDoorIntoSummer on Fri Aug 15th, 2008 at 11:24:54 PM EST


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