Stratospheric Ozone Negrito

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Information about Stratospheric Ozone Negrito

Published on February 20, 2008

Author: Stella


Stratospheric Ozone:  Stratospheric Ozone GEO 391 Kathleen M. Negrito Topics to Cover:  Topics to Cover Overview of Ozone Background Chemistry and Location of Ozone Role of Ozone Government Action on Ozone Ozone Depletion Monitoring Ozone Hole Measurement of Ozone from the Ground Measurement of Ozone from Space Background:  Background Ozone was first discovered in 1840 by Christian Frederic Schonbein who noticed a unique odor during electrical sparking and electrolysis experiments. So he named it after the Greek word that means smell (ozein). Ozone has a smell like burning electrical wire and is bluish in color. Chemical Ozone:  Chemical Ozone Each molecule of ozone has three oxygen atoms and is produced when oxygen molecules (O2) are broken up by energetic electrons or high energy radiation. Ozone (O3), the triatomic molecule of oxygen, is much less abundant, making up only one part in three million of all gases in the atmosphere. ( Slide5: Ozone is produced when O2 absorbs UV radiation at wavelengths of less than 242 nanometers, and is removed by photo-dissociation (breaking up of a molecule by photons) from sunlight for wavelengths greater than 290nm. O3 is also the major absorber of UV sunlight between 200 and 330nm. The combination of these processes is effective in maintaining a relatively constant amount of ozone in the layer, and in absorbing 90% of UV sunlight. Role of Ozone:  Role of Ozone The ozone layer prevents most ultraviolet (UV) and other high-energy radiation from penetrating to the earth's surface but does allow through sufficient ultraviolet rays to support the activation of vitamin D in humans. The full radiation, if unhindered by this filtering effect, would destroy animal tissue. 90% of the Ozone is in the Stratosphere http://Location of Ozone Role of the Ozone:  Role of the Ozone Ozone Depletion:  Ozone Depletion A group of chemicals known as halocarbons destroy ozone. The most familiar of these are chlorofluorocarbons (CFCs). Aerosols and old refrigerators have released CFCs into the atmosphere. UV radiation breaks down CFCs in the upper stratosphere, releasing chlorine. Once released, chlorine becomes a catalyst of ozone destruction. During this process, the ozone molecule is destroyed while the chlorine catalyst reforms. A single chlorine atom in the stratosphere can destroy about 100,000 ozone molecules. Ozone Depletion:  Ozone Depletion Government Actions:  Government Actions The ozone hole was discovered in 1985 yet scientist warned the world in 1974 that unless the world stop the use of ozone depleting chemicals, the ozone will deplete rapidly. As a result of 11 years of testing and confirmation, an agreement known as the Vienna Convention for the Protection of the Ozone Layer, which was a pledge by governments to protect the ozone layer. The specific commitments came in 1987 through the Montreal Protocol on Substances that Deplete the Ozone Layer. Ozone Story Government Actions:  Government Actions Vienna Convention of the Protection of the Ozone Layer: which outlines states' responsibilities for protecting human health and the environment against the adverse effects of ozone depletion, established the framework under which the Montreal Protocol was negotiated. Montreal Protocol and International Ozone Protection Policies: is a landmark international agreement designed to protect the stratospheric ozone layer. The treaty was originally signed in 1987 and substantially amended in 1990 and 1992. The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform). Amendments followed on substances. London Amendment Copenhagen Amendment Montreal Amendment Beijing Amendment Measuring Ozone:  Measuring Ozone Dobson Units used to measure ozone concentration in die atmosphere: 1 Dobson Unit (DU) is defined to be 0.01 mm thickness at STP (O°C and 1 ATM pressure) and spreads out evenly over the area, it would form a slab approximately 3mm thick corresponding about 300DU. The unit is named after G.M.B.Dobson, one of the first scientists to investigate atmospheric ozone (1920-1960). He designed the Dobson spectrometer which it is the standard instrument used to measure ozone from the ground. Monitoring Ozone Depletion:  Monitoring Ozone Depletion Below 220DU Is considered part Of the Ozone hole. Today’s Ozone Monitoring Ozone:  Monitoring Ozone Why is the hole mainly over Antarctica? Each winter, the air around the South Pole cools and begins circulating to the west. This vortex effectively isolates the air over Antarctica, with three effects: 1. Outside air, which is relatively ozone-rich, cannot mix in and sustain ozone levels. 2. Chemicals that tend to slow down the depletion reactions cannot mix with Antarctic air. 3. Heat from outside air is shut out, prolonging the period of very low stratospheric temperatures. Slide16: A similar vortex forms around the Arctic, but "atmospheric waves" caused by landmasses with high mountain ranges in the Northern Hemisphere frequently push the vortex off the pole, allowing warmer air into the Arctic. The relative warmth of the Arctic is the main reason why a similar ozone hole doesn't form over the North Pole. Monitoring Ozone Depletion:  Monitoring Ozone Depletion The chart shows NASA/NOAA satellite data comparing stratospheric chlorine and the thickness of the ozone layer. As stratospheric chlorine declined in response to the Montreal Protocol, the amount of stratospheric chlorine began to decline while the ozone layer began to recover. Monitoring Ozone Hole:  Monitoring Ozone Hole GENEVA, 21 August 2006: The recovery of the Earth's protective ozone layer, which was ravaged by chemicals in the 20th century, will take five to 15 years longer than predicted, mainly due to the availability of chemicals from old cars, and refrigerators still available and some chemicals still produced that can harm the ozone-2065. Monitoring the Ozone:  Monitoring the Ozone Measuring the Ozone from the Ground:  Measuring the Ozone from the Ground Dobson spectrophotometer can be used to measure both total column ozone and profiles of ozone in the atmosphere. Total ozone measurements are made by comparing a frequency of the ultraviolet spectrum strongly absorbed by ozone with one that is not. Measurements can be based on light from the sun, moon, or stars Brewer Spectrophotometer Monitoring Ozone from the Ground:  Monitoring Ozone from the Ground The Dobson spectrophotometer measures ultraviolet light from the Sun at 2 to 6 different wavelengths from 305 to 345 nm. By measuring UV light at two different wavelengths, the amount of ozone can be calculated. One of the wavelengths used to measure ozone is absorbed strongly by ozone (305 nm), whereas the other wavelength is not absorbed by ozone (325 nm). Therefore the ratio between the two light intensities is a measure of the amount of ozone in the light path from the sun to the observing spectrophotometer. Monitoring the Ozone from the Ground:  Monitoring the Ozone from the Ground Light Detection and Ranging (LIDAR) is an ozone measurement technique that relies on absorption of laser light by ozone. A telescope is used to collect ultraviolet light that is scattered by two laser beams - one of which is absorbed by ozone (308 nm) and the other is not (351 nm). By comparing the intensity of light scattered from each laser, a profile of ozone concentration vs. altitude is measured from 10 km to 50 km. Smart Balloons for sensing , Rockets, and Aircraft are other means of monitoring the ozone layer from the ground. GROUND-BASED MICROWAVE RADIOMETER-Atmospheric ozone profiles may be measured by using a groundbased millimetre wave radiometer operating at and around the centre frequency of an ozone absorption line. The retrieval of the ozone profile is based on the pressure broadening of the spectral line. Passive instruments Measuring Ozone from Space:  Measuring Ozone from Space Shuttle Ozone Limb Sounding Experiment-2 (SOLSE-2) as a demonstration of new technology that will be used on the next generation of meteorological satellites to monitor ozone change. Upper Atmosphere Research Satellite (UARS) The Upper Atmosphere Research Satellite (UARS) was launched in 1991 by the Space Shuttle Discovery and orbits at an altitude of 375 miles. Designed to operate for three years, six of its ten instruments continue to function, measuring ozone and chemical compounds found in the ozone layer. Solar Radiation and Climate Experiment (SORCE) A NASA-sponsored satellite mission that will provide state-of-the-art measurements of incoming x-ray, ultraviolet, visible, near-infrared, and total solar radiation. Earth Probe Total Ozone Mapping Spectrometer (EP-TOMS) Earth Probe Total Ozone Mapping Spectrometer (EP-TOMS), along with the Ozone Monitoring Instrument onboard AURA, are currently the only NASA spacecraft on orbit specializing in ozone retrieval- OMI GOME-Global Ozone Monitoring Experiment a nadir-scanning ultraviolet and visible spectrometer for global monitoring of atmospheric Ozone, was launched on-board ERS-2 in April 1995. SBUV-Solar Backscatter Ultraviolet Instrument instrument was developed at Goddard and is designed to measure ozone concentrations by comparing solar ultraviolet radiation with radiation scattered back from the Earth's atmosphere Aura Mission The Microwave Limb Sounder (MLS) experiments measure naturally-occurring microwave thermal emission from the limb (edge) of Earth's atmosphere to remotely sense vertical profiles of atmospheric gases, temperature, pressure, and cloud ice. Effects of Ozone Depletion:  Effects of Ozone Depletion Reference:  Reference

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