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The trace gas NO2 is emitted into the atmosphere in large quantities due to human activities such as traffic and industry. The residence time of NOx in the lower troposphere is short. Therefore observations of tropospheric NO2 contain important information on the emissions of nitric oxide, and the trends in these emissions. In the maps of troposheric NO2 made from GOME and SCIAMCHY observations the industrialised areas in the world are clearly visible. But also phenomena as the weekly cycle of traffic and industry and the major shiptracks on the ocean can be observed in these maps from satellite observations. Full text and more images. |
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Sulphur dioxide, SO2, enters the atmosphere as a result of both
natural phenomena and anthropogenic activities, such as combustion of fossil
fuels, oxidation of organic material in soils, volcanic eruptions, and
biomass burning.
Coal burning is the single largest man-made source of sulphur dioxide, accounting for about 50% of annual global emissions, with oil burning accounting for a further 25 to 30%. Note: Emissions of SO2 related to volcanic eruptions are covered by the Support to Aviation Control Service. Full text and more images. |
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Quicktime movie (65 Mb) of the airpollution in London during 24 hours, based on traffic emissions
for the year 2000. This pollution animation shows the pattern of Nitrogen Dioxide (NO2)
concentration over London during the course of one day. The major source of Nitrogen Dioxide is road traffic,
and the highest concentrations (deep red colour) can clearly be seen around the busiest roads during
the morning and evening rush hours. High Nitrogen Dioxide concentrations may trigger asthma attacks, or cause breathing difficulties for those with lung complaints or heart conditions. More information on the ESA portal. |
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The ozone layer is of vital importance for life on Earth because it strongly absorbs the harmful ultra-violet (UV) radiation from the Sun. The discovery of a rapid decline o f ozone over Antarctica each spring - the ozone hole - in the mid 1980s came as an unexpected and unpleasant surprise. Since the discovery of the ozone hole in 1984 a steady negative trend has been observed in the ozone abundance over the South Pole. This trend is related to the presence of man-made chlorofluorocarbons (CFCs). Implementation of the international Montreal protocol has resulted in a large reduction of emissions of CFCs and to a recently observed decrease of CFC concentrations in the atmosphere. As a consequence the Antarctic ozone hole is expected to recover this century. However, future predictions of this expected recovery remain uncertain. The recovery will depend on complex climate-chemistry interactions associated to the greenhouse effect. It will further depend on the development of emissions of ozone-depleting substances. The discovery of the ozone hole, and the subsequent international measures taken as a result of the Montreal protocol, demand a world-wide and long-term monitoring of the ozone layer, both from the ground and from space. Full text and more images. |
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The ozone hole is not always present. It is formed in August when the light returns to the cold winter Pole and when the catalytic processes involving chlorine and bromine rapidly destroy the available ozone. The ozone hole disappears around November-December when the stratospheric vortex - which traps the ozone depleted air - is warming up and becomes unstable. Full text and more images. |
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Ozone strongly absorbs in the short-wave UV, the UV-B. Day to day
variations in stratospheric ozone amount, ozone depletion and the Antarctic ozone hole effect
the biosphere via the UV-B irradiance reaching the Earth's surface. The effects on humans are
described by the erythemal (sunburn) effective UV irradiance given as the internationally
harmonised UV Index. The UV Index serves as vehicle to raise public awareness of the risk of
excessive UV exposure and to alert people to adopt sun protection measures. The UV Index forecasts for all effective atmospheric conditions are based on the PROMOTE ozone forecast, they are provided with a global coverage and a high resolution European coverage, and are presented WHO-conform. Forecasts for more than 1150 sites worldwide are presented with 48 maps allowing for a high regional resolution. Short sun protection messages are displayed by click on the forecasted UV Index. Full text and more images. |
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This movie shows the diurnal cycle of the sunburn time, i.e. the time until first reddening of human skin in minutes, over clear sky Europe on 10. June 2007 for a person with skin type II. Red colours represent short sunburn times corresponding to high UV intensities. The movie gives an imagination how the sunburn time varies locally and spatially with solar elevation from the early morning hours into the evening. As illustrated minimum sunburn times are always occuring at local noon under cloud-free conditions. Sunburn times can actually reach minimum values of 10 minutes at southern latitudes. The stuctures of mountaneous areas, as for example the Alps, are clearly identificable since the UV intensity is increasing with terrain altitude by about 10% per 1000m . Such data form the basis of UV-Check, one sub-service of the PROMOTE UV information service. They were pre-calculated every day by the use of total ozone amounts as measured with the GOME-2 instrument onboard the European satellite MetOp. Clouds obscuring the sun would reduce local UV intensities and prolong the sunburn times correspondingly. Reflecting snow or water surfaces on the other hand would enhance the UV intensity. Via the UV-Check internet or SMS service a user has the option to take into account such environmental conditions at every time of the day and at his individual location within the region of Europe. |
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Volcanic eruptions may eject large amounts of ash (aerosols) and trace gases
such as sulphur dioxide (SO2) into the atmosphere. These ejecta
can have considerable impact on the safety of air traffic and on human
health. Ground-based monitoring is carried out at only a limited number of
volcanoes: most volcanoes are not monitored on a regular basis, in
particular the remotely located volcanoes. Global observations of SO2 and
aerosols derived from satellite measurements in near-real-time are therefore
necessary to assess possible impacts of volcanic eruptions on air traffic
control.
Note: Emissions of SO2 related to anthropogenic activies are part of the Air Quality Record Service. Full text and more images. |
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This page focusses on the near-infrared / short wave infrared (NIR/SWIR) nadir measurements of SCIAMACHY. These spectra of scattered and reflected solar radiation enable the retrieval of total column amounts of important atmospheric (trace) gases on the global scale. The total vertical column of a gas is its vertically integrated number density concentration profile in number of molecules per unit area (molecules per cm2). Mainly for CH4, CO2, CO, H2O, N2O, and O2 column retrieval we have developed a fast modified DOAS algorithm called WFM-DOAS. For the relatively well-mixed greenhouse gases CH4 and CO2 we generate column averaged mixing ratios, denoted XCH4 and XCO2. They are computed by normalizing the measured greenhouse gas columns by the measured total airmass (number of air molecules per cm2) obtained from, e.g., simultaneously measured O2 columns. Full text and more images. |
Ronald van der A, last modified: March 2008