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  • Atmospheric layers >> Troposphere | BIRA-IASB
    an altitude of about 8 15 kilometres This region is characterized by decreasing temperature with increasing altitude The study of the troposphere is very important because we breathe the air in this layer of air The troposphere contains about 85 of the atmosphere s total mass Tropospheric processes such as the water or hydrologic cycle the formation of clouds and rain and the greenhouse effect have a great influence on

    Original URL path: http://www.bira-iasb.be/en/topics/earthsystem/atmosphere-layers-tropo.htm (2016-04-27)
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  • Ozone, influence on humans and living creatures | BIRA-IASB
    damaging ultraviolet radiation allowing only a small part of the radiation to reach the Earth Absorbing ultraviolet radiation ozone is a source of heath and is in this way actually responsible for the formation of the stratosphere itself which is a layer where temperature rises with increasing height Ozone is essential to explain the temperature structure of the terrestrial atmosphere If unhindered by the filtering effect of the ozone the

    Original URL path: http://www.bira-iasb.be/en/topics/naturalhazards/ozone-influence.htm (2016-04-27)
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  • BIRA-IASB monitors the effect of the Montreal Protocol
    of Montreal Protocol The stratospheric ozone layer protects the Earth s biosphere from a large part of the ultraviolet radiation emitted by the Sun Appearing in the beginning of the 1980s two spectacular phenomena demonstrated that certain human activities threatened this natural protection against ultraviolet rays the destruction of almost all of the ozone in the lower Antarctic stratosphere each spring the destruction of 3 each decade of the ozone layer at our latitudes In September 1987 the Montreal Protocol was established in reaction to these alarming discoveries It has since been regulating the production and use of many chemical substances that release in the stratosphere chlorine and bromine which are responsible for the ozone destruction Monitoring stratospheric ozone and the substances controlling its concentration is one of the missions of the Royal Belgian Institute for Space Aeronomy BIRA IASB The measurements the Institute makes from satellites and observational networks enable to check the enforcement and effects of the Montreal Protocol discover new phenomena improve and validate predictive atmospheric composition models Thanks to these models we can explore our future stratosphere and its interactions with the climate They help the international community to knowingly take decisions like for instance to

    Original URL path: http://www.bira-iasb.be/en/topics/globalchange/montrealprotocol.htm (2016-04-27)
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  • BIRA-IASB monitors the ozone layer
    Reunion Those stations are part of the Network for the Detection of Atmospheric Composition Change NDACC a network taken on by the World Meteorological Organisation WMO and the United Nation Environment Programme UNEP Instruments on the roof of Jungfraujoch station Credits BIRA IASB J C Lambert Satellite observations BIRA IASB is also involved in the definition and development of several satellite instruments which enable the Institute to extend to the global scale the detailed analysis made in the stations After submitting and tracking the implementation of the GOME spectrometer the first European instrument in orbit dedicated to the study of the ozone layer and of its successor SCIAMACHY a contribution of Belgium Germany and the Netherlands to the ESA ENVISAT satellite BIRA IASB is now carrying on with its long term ozone monitoring mission with the GOME 2 and IASI instruments onboard the EUMETSAT meteorological satellites To fill the dramatic gap expected in the number of atmospheric vertical sounders that will be operating in the next 5 years BIRA IASB is devellopping ALTIUS a limb imaging spectrometer on a micro satellite platform Observations show stabilisation Ground based and satellite observations above Europe have shown a recent stabilisation of the ozone

    Original URL path: http://www.bira-iasb.be/en/topics/naturalhazards/ozone-bira-iasb.htm (2016-04-27)
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  • Substances destroying ozone | BIRA-IASB
    main chlorinated and brominated species Chlorine gases Remote sensing in the infrared range works particularly well in measuring the chlorine gases like HCl ClONO2 CFC s HCFC s This is why BIRA IASB installed on the Ile de La Reunion in the Indian Ocean on the east of Madagascar a Fourier transform spectrometer working in the solar infrared range Since 2002 the data gathered by this spectrometer have been archived in the NDACC network data base The coordinated data analysis of this network shows a decline in chlorine gas sources whose production has been limited or even totally stopped by the Montreal Protocol in 1987 a reduction of stratospheric HCl since 1996 1997 The HCl measures BIRA IASB made on the Ile de La Réunion with a Fourier transform infrared spectrometer FTIR confirm the predictions of the SLIMCAT model Brominated species Measurements made by another spectrometer network working this time in the ultraviolet spectral range and to which BIRA IASB has been contributing since 1994 with an instrument installed in Norway lead to the same conclusions for the brominated species These results confirmed by data from the SCIAMACHY satellite orbiting Earth since 2002 univocally show the impact of the Montreal

    Original URL path: http://www.bira-iasb.be/en/topics/naturalhazards/ozone-destruction.htm (2016-04-27)
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  • Mechanisms determining ozone abundance | BIRA-IASB
    ozone and the halogenated substances destroying it is complex their distribution and evolution in the stratosphere are determined by a succession of chemical and physical mechanisms even depending on the meteorology To understand them a global and regular cartography of the different atmospheric constituents like NO2 BrO aerosols and OCIO is required OCIO for example is the indicator of an ozone destruction catalytic cycle combining chlorine and bromine The GOME satellite and its successors have mapped on a continuous basis the integrated column of these constituents since 1995 But their ability to measure the vertical distribution is very limited And most of all they cannot take measures in the polar night darkness Yet it is precisely during this period that the vortex is developing above the pole The vortex is where the mechanisms that would lead to the formation of polar ozone holes in spring will set off GOMOS probes the atmosphere observing the stars By observing the stars through the atmosphere the GOMOS instrument onboard the ENVISAT satellite is able to map stratospheric ozone all around the globe including during polar night and in only three days GOMOS also detects other constituents involved in ozone chemistry like NO2 NO3

    Original URL path: http://www.bira-iasb.be/en/topics/naturalhazards/ozone-mechanisms.htm (2016-04-27)
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  • What is UV and where does it come from? | BIRA-IASB
    wave like in nature and therefore is characterized by a wavelength related to the composition and temperature of the transmitter in this case the Sun The electromagnetic spectrum describes the distribution of the different types of radiation over a wide wavelength spectrum In descending order of wavelength the spectral range extends from radio waves long wavelengths up to tiny gamma rays small wavelengths with the infrared IR visible and ultraviolet UV ranges in between where the Sun emits the most of its radiation Our human eye is only sensitive to a small fraction of the solar spectrum called the visible between 4 10 7 m and 7 10 7 m that includes all colors of the rainbow from violet to red Just below this range between 1 0 10 7 m and 4 10 7 m we find the ultraviolet rays UV especially energetic but invisible to the human eye and beyond the visible and longer than 7 10 7 m infrared wavelengths begin This range is associated with the concept of heat as hot objects emit such radiation At BIRA IASB we mainly focus on UV Lucky we are that the atmosphere is acting as a protector shield against

    Original URL path: http://www.bira-iasb.be/en/topics/naturalhazards/uv-whatisit.htm (2016-04-27)
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  • Why control UV doses received? | BIRA-IASB
    major issues Prolonged exposure to ultraviolet radiation can cause significant damage to living organisms For example The painful experience of a sunburn erythema is a visible manifestation of a type of defense mechanism set up by the cells of our skin against excessive UV doses The ultraviolet radiation and particularly the most aggressive UV B can cause significant damage to the human genome causing irreversible changes in the gene sequences of our DNA Fortunately in most cases the organisms are able to overcome these attacks with natural self correcting mechanisms to control the risks associated with such an exposure For instance most of us are able to tan However at higher doses the human species can develop certain photo allergies undergo accelerated aging of the skin suffer from eye cataracts or develop certain types of skin cancer such as melanoma in the most serious cases Risks of UV exposure for each human being is not equal In conclusion the risks incurred by people who expose themselves to UV voluntarily or not are mainly related to type of ultraviolet light absorbed the intensity of it dose received frequency of exposure age at which one is exposed mature skin or not Thus

    Original URL path: http://www.bira-iasb.be/en/topics/naturalhazards/uv-why.htm (2016-04-27)
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