Impacts of the solar eclipse of 29 March 2006 on the surface ozone and nitrogen dioxide concentrations at Athens, Greece

International audienceThe behavior of surface ozone and nitrogen dioxide concentration as well as the variations in various meteorological parameters before, during and after the total solar eclipse of 29 March 2006 has been examined. This analysis is based on measurements performed at four stations located in the greater Athens basin in Greece. The experimental data demonstrated that the solar eclipse phenomenon affects the surface ozone and nitrogen dioxide concentrations as well as the temperature, the relative humidity and the wind speed near the ground. The reduction of the solar ultraviolet radiation at 312 and 365 nm reached 97% and 93% respectively, while the air temperature dropped, the relative humidity increased and the wind speed decreased. The percentage change (decrease) of surface ozone concentration was maximized one hour after the maximum phase of the eclipse due to the decreased efficiency of the photochemical ozone formation. The surface nitrogen dioxide concentration increased and the time lag of the nitrogen dioxide response to the solar eclipse was found to be different for each station. A plausible cause for the increase in NO2 concentration may be the conversion of NO to NO2 through reaction with pre-existing O3 along with the low photolysis rates of NO2 as a consequence of the decreased solar radiation during the solar eclipse event.In general, the time response to the eclipse phenomenon was different for each of the aforementioned parameters

Impacts of the solar eclipse of 29 March 2006 on the surface ozone concentration, the solar ultraviolet radiation and the meteorological parameters at Athens, Greece

International audienceIn this study the variations in the surface ozone concentration, the solar ultraviolet radiation and the meteorological parameters at the ground before, during and after the total solar eclipse of 29 March 2006 have been examined. This analysis is based on the measurements performed at four stations located in the greater Athens basin in Greece. The experimental data demonstrated that the solar eclipse phenomenon affects the surface ozone concentration as well as the temperature, the relative humidity and the wind speed near the ground. The decrease in the surface ozone concentration that observed after the beginning of the eclipse event lasted almost two hours, probably due to the decreased efficiency of the photochemical ozone formation. The reduction of the solar ultraviolet radiation at 312 and 365 nm reached 97% and 93% respectively, while the air temperature dropped, the relative humidity increased and the wind speed decreased

Impacts of the solar eclipse of 29 March 2006 on the surface ozone concentration, the solar ultraviolet radiation and the meteorological parameters at Athens, Greece

In this study the variations in the surface ozone concentration, the solar ultraviolet radiation and the meteorological parameters at the ground before, during and after the total solar eclipse of 29 March 2006 have been examined. This analysis is based on the measurements performed at four stations located in the greater Athens basin in Greece. The experimental data demonstrated that the solar eclipse phenomenon affects the surface ozone concentration as well as the temperature, the relative humidity and the wind speed near the ground. The decrease in the surface ozone concentration that observed after the beginning of the eclipse event lasted almost two hours, probably due to the decreased efficiency of the photochemical ozone formation. The reduction of the solar ultraviolet radiation at 312 and 365 nm reached 97% and 93% respectively, while the air temperature dropped, the relative humidity increased and the wind speed decreased

Investigation of the microphase separation in blends of polyurethane-based ionomers

The separation in blends of polyurethane-based ionomers was investigated. Four relaxation mechanisms were shown by dielectric thermally stimulated depolarization current (TSDC) measurements. The subglass secondary γ- and β-relaxations were found to be related to local motions; the α-relaxation was related to the glass transition of the amorphous soft phase of the ionomers.The Maxwell-Wagner-Sillars (MWS) relaxation was related to polarization caused by the motion of ions. A criterion expressing a relative degree of phase mixing was also introduced. It appeared that the structures and properties of polyurethane-based ionomers was not simple functions of their composition