ChArMEx Science - Atmospheric Conveyor belt dumps Indian Pollution in the Mediterranean
Written by Hamonou   
Tuesday, 04 August 2015 10:57

Two International teams one led by researchers from Météo France/CNRM/GAME (http://www.atmos-chem-phys.net/14/11427/2014/acp-14-11427-2014.html) and the other one led by researchers from the UPEC/CNRS/LISA (http://www.atmos-chem-phys.net/14/10589/2014/acp-14-10589-2014.html) have identified new proofs of the existence of an atmospheric conveyor belt dumping Indian produced pollution into the Eastern Mediterranean basin!

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Methane mixing ratio (left) and ozone concentration (right) derived from IASI spaceborne instrument showing a clear west-east gradient with higher levels of pollutants over the Eastern Mediterranean

Teams have been looking at time-series of satellite measurements of greenhouse gases (ozone and methane) and found systematic maximum of summer concentrations over the Eastern Mediterranean. Something was adding greenhouse gases creating a steep west-east gradient of concentrations.To find out what was this mechanism state-of-art computer models capable of simulating both the atmospheric circulation and the chemical transport as well as meteorological analyses have been used. It turned out that these simulations pointed at the Asian Monsoon!

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How a typical Asian Monsoon Meteorological results in conveying Indian Pollution to the Mediterranean

The Asian Monsoon traps and uplifts high amounts of methane and ozone that are then transported towards North Africa and Middle East by the Asian Monsoon Anticyclone to finally reach and descent in the Eastern Mediterranean basin.

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Last Updated on Thursday, 17 September 2015 16:08
 
Teaser
Written by Hamonou   
Thursday, 30 July 2015 16:31

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Last Updated on Wednesday, 16 September 2015 08:22
 
ChArMEx Science - Aerosols decrease rain and increase heat waves intensity
Written by Hamonou   
Thursday, 04 June 2015 14:08

ChArMEx and HyMeX show that aerosols over the Mediterranean dry its atmosphere and increase the intensity of heat waves

A team from CNRM (Toulouse, France), LA (Toulouse, France), ICTP (Trieste, Italy)  and the ETH Zurich (Switzerland) has recently published (http://link.springer.com/article/10.1007/s00382-014-2205-6) the results of regional climate simulations with an atmosphere-ocean coupled model accounting for radiative effects of aerosols on solar and thermal infrared radiation, showing that aerosols over the Mediterranean basin tend to reduce precipitation and strengthen the intensity of heat waves.

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Rain intensity difference with aerosols (AER) or without (NO) in forced mode (F) (left) and coupled mode (C) (right) (Nabat et al., 2014)

 

The Mediterranean atmosphere is heavily loaded with aerosols especially during spring and summer. Because aerosol particles scatter incident solar radiation, part of it will never reach the surface. In addition, some aerosols (especially soot carbon and Saharan dust) absorb solar radiation and heat the atmospheric layers where they are present. Thus, aerosols have a tendency to significantly reduce the amount of energy that reaches the surface, reducing surface temperature and water evaporation, and to increase the air temperature of turbid layers, reducing the cloud cover. On an annual average the reduction in precipitation reaches 0.2 mm/day over the Mediterranean basin, which represents about 10% of the annual average. Besides, because of induced changes on atmospheric dynamics, it was found that African dust aerosol increased by 0.5°C (~15%) a heat wave observed in July 2006. These aerosol impacts are attenuated in atmospheric only climate models that use a prescribed sea-surface temperature

The first author of this study, Pierre Nabat from CNRM, has been awarded the André Prudhomme 2015 prize by the Société Météorologique de France for his outstanding PhD performed in the framework of HyMeX and ChArMEx and that includes this study.

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Last Updated on Wednesday, 26 August 2015 16:58
 
ChArMEx Science - Less aerosols bring more light and more heat to Europe!
Written by Hamonou   
Friday, 22 May 2015 10:08

ChArMEx and HyMEx show that less sulfate aerosols over Europe has brought more light and more heat to the Europeans.

A team from CNRM, LA, the University of Girona (Spain) and the ETH Zurich (Switzerland) has recently published (http://onlinelibrary.wiley.com/doi/10.1002/2014GL060798/pdf) the results of a new kind of modelisation showing that sulfate aerosols reduction over Europe since 1980ies mostly explains the brightening of Europe surface that has been measured since then.

Sulfate aerosols standing in mid-air act has sunshades that reflects sunlight to the outer space. The reduction of the number of such sunshades since the 1980ies due to the set-up of emission control policies in Europe has thus had 2 sides effects: it has brought more light to the Europeans and brought more heat!


brightening

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Model vs Measurements (colored circles) for (left) the surface solar radiation trend (W/m2/decade) for 1980-2007, and (right) the temperature trend (°C/decade) at 2 m for 1980-2007

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Last Updated on Wednesday, 26 August 2015 16:59
 
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