Release Of Chlorofluorocarbons Research Articles

The ozone layer and its impact on human health

The formation of life on Earth and the presence of various ecosystems were determined by several factors, and one of the most important among them is the atmosphere. In particular, the ozone layer (O3), located in the second layer of the atmosphere, 12-35 kilometers above the earth's surface, in the stratosphere, where 90% of ozone is present, the remaining amount of ozone, about 10%, is located in the troposphere. Stratospheric ozone is important for environmental protection. At present, uncontrolled industrial activities and other actions have put humanity at great risk, which has resulted in the release of chlorofluorocarbons and other halocarbons into the air. After being released in the stratosphere, molecules of these compounds interact with ultraviolet radiation to release bromine and chlorine. It is a known fact, that one molecule of CFC can destroy as many as 100,000 ozone molecules. Ozone-depleting substances and factors include carbon tetrachloride, methyl chloroform, hydrobromofluorocarbons, methyl bromide, bromochloromethane, nitrogen oxides, space rockets, airplanes flying at 12-15 km overhead, global warming, etc. The previously mentioned reactions and substances caused the depletion of the ozone layer and the so-called occurrence of "Ozone holes", discovered near the poles. It can be said assuredly that the depletion of the ozone layer and its resulting effects, such as premature aging, an increase in the number of skin cancer patients, in particular basal cell cancer and squamous cell cancer, weakening of the immune system, damage to the cornea, conjunctival membrane, crystal and retinal membrane of the eye, and others have become one of the serious challenges of modernity. All of the aforementioned led to the Montreal Protocol, aimed to protect the ozone layer by reducing ozone-depleting gases. Georgia officially joined the "Montreal Protocol" and the "Vienna Convention" in 1996. It is also worth noting that dealing with such a global problem and the experience gained within it will also help us  in the fight against climate change.

Application of Eco-Friendly Blue-Light Emitting Quantum-Dot UV Camera By Energy-Down-Shift Mechanism

The ozone layer protecting all living organisms from ultra-violet (UV) radiation has been destroyed because of excessive release of chlorofluorocarbons, so that reaching the UV radiation on the earth surface has been increased continuously. It has been reported that UV radiation would cause cutting DNA chain, skin cancers and immunity damage. In particular, the most common type of skin censers, such as basal cell carcinoma, squamous cell carcinoma and melanoma, are caused by sun exposure, especially overexposure to UV light [1]. Here, we developed a novel eco-friendly QD UV camera where visible-light emitting core/shell QDs were implemented on the C-MOS image sensor (CIS) pixels. QD would absorb the UV light and emit the visible light via energy-down-shift (EDS) mechanism [2], which could precisely tune the peak wavelength and full-width at half-maximum (FWHM) of the emitting visible light to maximize the photo-responsivity. Figure 1 shows the schematic structure of QD UV CIS pixel which consist of four-transistors and one-photodiode implemented with eco-friendly core/shell QDs which uniformly coated selectively on only Si photodiode region. As the UV light is absorbed the EDS-QD layer, QD would emit the blue-visible light which go through the silicon photodiode and increase the pixel intensity simultaneously. The UV photograph was shown by taking pictures, and calculating the difference pixel intensity between without QDs and with QDs. Figure 2 shows that the core/shell QDs would absorb the light under 450-nm-wavelength and emit the blue-visible light at its peak wavelength of 434.7 nm, the quantum yield of 68.4%, and FWHM of 19.2 nm. The average diameter of core/shell QD were ~8.18 nm and it shows continuous lattice fringes and highly crystalline structure of core/shell QDs. We confirmed that the photo-responsivity of the Si photodiode implemented with the EDS-QDs was 0.78 A/W and the output voltage sensing margin (Vout, dark-state – Vout, photo-state) of CIS pixels increased 195% at 365-nm-wavelength compared to the CIS without implementing QDs. QD UV cameras could be applied to many fields that use UV light. Figure 3 shows that the sunscreen-applied area of the human hand would reflects UV light so the pixel intensity are high. On the other hand, areas that are not applied sunscreen have low pixel intensity because human skin would absorbs UV light. We can check whether the sunscreen is well-applied on skin by simply taking a picture through the UV camera. Figure 4 shows another application of QD UV camera: skin care. The sebum on the face can be confirmed easily by taking a picture with the QD UV camera. It shows the size and distribution of sebum on the face very accurately. We will present various applications that could be realized through the eco-friendly QD UV camera in detail. * This work was financially supported by the Brain Korea 21 Plus Program in 2018. Reference [1] T. Bald, et al., Nature 507, 109–113 (2014). [2] S. W. Baek, et al., Phys. Chem. Chem. Phys. 16, 18205 (2014). Figure 1

Atmospheric Chemistry and Climate in the Anthropocene / Chemia Atmosferyczna I Klimat W Antropocenie

Abstract Humankind actions are exerting increasing effect on the environment on all scales, in a lot of ways overcoming natural processes. During the last 100 years human population went up from little more than one to six billion and economic activity increased nearly ten times between 1950 and the present time. In the last few decades of the twentieth century, anthropogenic chlorofluorocarbon release have led to a dramatic decrease in levels of stratospheric ozone, creating ozone hole over the Antarctic, as a result UV-B radiation from the sun increased, leading for example to enhanced risk of skin cancer. Releasing more of a greenhouse gases by mankind, such as CO2, CH4, NOx to the atmosphere increases the greenhouse effect. Even if emission increase has held back, atmospheric greenhouse gas concentrations would continue to raise and remain high for hundreds of years, thus warming Earth’s climate. Warming temperatures contribute to sea level growth by melting mountain glaciers and ice caps, because of these portions of the Greenland and Antarctic ice sheets melt or flow into the ocean. Ice loss from the Greenland and Antarctic ice sheets could contribute an additional 19-58 centimeters of sea level rise, hinge on how the ice sheets react. Taking into account these and many other major and still growing footprints of human activities on earth and atmosphere without any doubt we can conclude that we are living in new geological epoch named by P. Crutzen and E. Stoermer in 2000 - “Anthropocene”. For the benefit of our children and their future, we must do more to struggle climate changes that have had occurred gradually over the last century.

Climate Change: Its Causes, Effects and Control

One of the most controversial issues about the environment today is the issue of climate change. This phenomenon has been observed over time, with changes in weather patterns and climatic factors like temperature, pressure, and humidity. The cause is either human induced through the burning of fossil fuels and release of chlorofluorocarbons; or naturally through volcanic eruptions and continental plate movements. The evidence of climate change has been obtained from changes in weather patterns, global warming, vegetation changes, precipitation and archeology. These changes have resulted in negative consequences for the environment like drought, flood and depletion of the ozone layer. It has also caused serious health problems leading to deaths of people, decreased food production from unsteady rainy seasons and loss of biodiversity. Measures that can be taken to control it include: use of renewable energy sources, afforestation and strict government policies on emissions of carbon dioxide. DOI: 10.5901/jesr.2013.v3n10p73

Impact of UV-B radiation on photosynthesis – an overview

Ultraviolet-B (UV-B) radiation constitutes a minor part of the solar spectrum, being most of this solar radiation absorbed by the UV-screening stratospheric ozone layer. Yet, a global depletion of the ozone layer, largely due to the release of chlorofluorocarbons caused by human activities, has resulted in an increase of solar UV-B radiation at the earth’s surface. Accordingly, in the temperate latitudes, such ozone decrease reached ca. 3% and 6% in the North and South hemispheres, respectively, between 2002 and 2005 (as compared to the 1970s). Despite the uncertainty of long-term predictions, it is also estimated an UV-B increase of 5-10% over temperate latitudes within the next 15 years In this context, this work aim at to present an overview of plants sensitivity/tolerance to UV-B irradiation mostly considering the key photosynthetic metabolism. doi: http://dx.doi.org/10.9755/ejfa.v24i6.14673

Impact of UV-B radiation on photosynthesis – an overview

Ultraviolet-B (UV-B) radiation constitutes a minor part of the solar spectrum, being most of this solar radiation absorbed by the UV-screening stratospheric ozone layer. Yet, a global depletion of the ozone layer, largely due to the release of chlorofluorocarbons caused by human activities, has resulted in an increase of solar UV-B radiation at the earth’s surface. Accordingly, in the temperate latitudes, such ozone decrease reached ca. 3% and 6% in the North and South hemispheres, respectively, between 2002 and 2005 (as compared to the 1970s). Despite the uncertainty of long-term predictions, it is also estimated an UV-B increase of 5-10% over temperate latitudes within the next 15 years In this context, this work aim at to present an overview of plants sensitivity/tolerance to UV-B irradiation mostly considering the key photosynthetic metabolism. doi: http://dx.doi.org/10.9755/ejfa.v24i6.14673

A review of major chlorofluorocarbons and their halocarbon alternatives in the air

To establish a proper regulation strategy on the emissions of major halocarbons including chlorofluorocarbons (CFCs), carbon tetrachloride (CCl4), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), it is essential to assess their environmental behavior in relation to social and technological changes for their control. The production and release of CFCs and CCl4 increased rapidly to peak between the 1970s and 1980s and then decreased dramatically from the end of the 1980s in good accordance with the phase out schedules set by the Montreal Protocol. Both HCFCs (e.g., HCFC-124, HCFC-141b, and HCFC-142b) and HFCs (e.g., HFC-134a) have been introduced as CFCs alternatives between the late 1980s and early 1990s. However, these alternatives have already been or will be scheduled to be phased out because of their involvement in ozone destruction and global warming. In light of all the complexities associated with the global chemistry of CFCs and their alternatives, this paper provides an overview of their production and emission trends, their relationship with the ozone depletion phenomenon, the chemistry regulating their removal processes, and their distribution patterns with diverse temporal and spatial scales.

Antarctic terrestrial ecosystem and role of pigments in enhanced UV-B radiations

The terrestrial ecosystem of Antarctica are among the most extreme on earth, challenging the communities and making their existence difficult by rapidly increasing annual summer influx of solar ultraviolet radiations (UV-R), extremely cold conditions and lesser availability of nutrients. Spring time ozone depletion is due to release of chlorofluorocarbons in the earth atmosphere and is a serious cause of concern among environmentalists. Antarctic continent is mostly dominated by cryptogamic plants with limited distribution in different parts of the icy continent however; their distribution is mostly confined to Sub-Antarctic region. By the virtue of light requirement, cryptogams are exposed to extreme seasonal fluctuation in photosynthetically active radiation (PAR), and ultraviolet (UV) radiation which are closely associated with photosynthetic pigments in photoautotrophic organisms. Antarctic cryptogams cope up the stress imposed by UV radiation by the development of efficient systems for repairing damage by synthesis of screening compounds such as UV-B absorbing pigments and anthocyanin compounds. A major part of the UV absorbing compounds are appeared to be constitutive in lichens which are usnic acid, perlatolic acid and fumarphotocetraric acid which is particularly induced by UV-B. Secondary metabolites such as phenolics, atranorin, parietin and melanin also enhance the plant defense, by different molecular targets in specific solar irradiance and potential for increased antioxidative protection to UV induced vulnerability.

Ultraviolet radiation negatively affects growth but not food quality of arctic diatoms

We studied the short‐term effects of ultraviolet radiation (UV radiation, 280–400 nm) on the fatty acid composition and cellular stoichiometry of three dominant arctic diatom species (Thalassiosira antarctica var. borealis, Chaetoceros socialis, Bacterosira bathyomphala) in laboratory experiments. Photosynthetic efficiency during UV irradiation was inhibited 90%, which led to a substantial reduction in biomass. In contrast to results of previous studies, the percentage of total polyunsaturated fatty acids (PUFAs) did not decrease during UV exposure. Instead, the two major PUFAs, 16:4(n‐1) and 20:5(n‐3), of B. bathyomphala increased, and the PUFA content of T. antarctica and C. socialis did not change significantly. However, the monounsaturated fatty acid 16:1(n‐7) content in all three species substantially decreased during UV radiation. Since high concentrations of 16:1(n‐7) are usually associated with exponential growth under favorable conditions, UV radiation probably did not affect a specific type of fatty acid directly; the fatty acid profile rather reflected a general deterioration in the algal physiological state. The nutritional quality of the fatty acids did not decrease during UV exposure; the C: P and N: P ratios decreased by 50% in all species, whereas the C:N ratios increased slightly in two species. Our results indicate that UV radiation has strong negative effects on photosynthesis and biomass production, but not on food quality with regard to PUFAs and stoichiometry.

Solar UV‐B radiation affects below‐ground parameters in a fen ecosystem in Tierra del Fuego, Argentina: implications of stratospheric ozone depletion

AbstractStratospheric ozone depletion caused by the release of chlorofluorocarbons is most pronounced at high latitudes, especially in the Southern Hemisphere (including the so‐called ‘ozone hole’). The consequent increase in solar ultraviolet‐B radiation (UV‐B, 280–315 nm) reaching the earth's surface may cause a variety of alterations in terrestrial ecosystems. Most effects might be expected to occur above‐ground since sunlight does not penetrate effectively below‐ground. Here, we demonstrate that solar UV‐B radiation in a fen in Tierra del Fuego (Argentina), where the ozone hole passes overhead several times during the Austral spring, is causing large changes of below‐ground processes of this ecosystem. During the third and fourth year of a manipulative field experiment, we investigated root systems in these plots and found that when the ambient solar UV‐B radiation was substantially reduced, there was a 30% increase in summer root length production and as much as a threefold decrease in already low symbiotic mycorrhizal colonization frequency of the roots compared with plots receiving near‐ambient solar UV‐B. There was also an apparent shift toward older age classes of roots under reduced solar UV‐B. Such large changes in root system behaviour may have decided effects on competition and other ecological interactions in this ecosystem.

99/03956 United states department of energy large commercial absorption chiller development program: Garland, P. W. et al. AES (Am. Soc. Chem. Eng.), 1998, 38, (Proceedings of the ASME Advanced Energy Systems Division, 1998), 271–275

To establish a proper regulation strategy on the emissions of major halocarbons including chlorofluorocarbons (CFCs), carbon tetrachloride (CCl4), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), it is essential to assess their environmental behavior in relation to social and technological changes for their control. The production and release of CFCs and CCl4 increased rapidly to peak between the 1970s and 1980s and then decreased dramatically from the end of the 1980s in good accordance with the phase out schedules set by the Montreal Protocol. Both HCFCs (e.g., HCFC-124, HCFC-141b, and HCFC-142b) and HFCs (e.g., HFC-134a) have been introduced as CFCs alternatives between the late 1980s and early 1990s. However, these alternatives have already been or will be scheduled to be phased out because of their involvement in ozone destruction and global warming. In light of all the complexities associated with the global chemistry of CFCs and their alternatives, this paper provides an overview of their production and emission trends, their relationship with the ozone depletion phenomenon, the chemistry regulating their removal processes, and their distribution patterns with diverse temporal and spatial scales.

Helium as a Replacement for Dichlorodifluoromethane in Class II Biological Safety Cabinet Integrity Testing

Dichlorodifluoromethane was commonly used for many years as a tracer gas for leak testing biological safety cabinets. International agreement to ban release of chlorofluorocarbons into the atmosphere led the United States Environmental Protection Agency to regulate the discharge limit to zero when adequate substitutes are available. Hence the need arose to develop a leak test using an alternative tracer gas that is environmentally friendly. Helium was compared to refrigerant 12 and found to be an adequate substitute in this testing of Class II Type A biological safety cabinets. A waiver was obtained from NSF International to permit the use of the proposed helium leak test as an alternative to the Halogen Leak Test.

Navy Investigations of HFC‐134a as a Replacement for CFC‐12 in Shipboard Applications

ABSTRACTGlobal concerns about the depletion of the earth's protective stratospheric ozone layer caused in part by the atmospheric release of chlorofluorocarbons (CFCs), have prompted the United States Congress in the 1990 Amendments to the U.S. Clean Air Act to require a large reduction in the production of CFCs and a total production ban of CFCs by the year 2000.This production ban date was recently accelerated by President Bush to 31 Dec. 1995. The U.S. Navy used approximately 2 million pounds of CFC‐12 (R‐12), 415 thousand pounds of CFC‐114 (R‐114) and 111 thousand pounds of CFC‐11 (R‐11) in calendar year 1990. These CFCs are mostly used as refrigerants in shipboard air conditioning and refrigeration plants in critical applications including cooling of vital shipboard sensors, communications, navigation and weapon systems. Naval Sea Systems Command (NavSea) has an aggressive research and development effort underway to investigate environmentally acceptable substitutes for CFCs for eventual fleet implementation. A potential substitute for CFC‐12 in air conditioning and refrigeration plants is HFC‐134a (1,1,1,2 Tetrafluoroethane). This paper presents Navy HFC‐134a investigation results to date, planned qualification tests, and future shipboard HFC‐134a air conditioning plant designs.

Free Radicals Within the Antarctic Vortex: The Role of CFCs in Antarctic Ozone Loss

How strong is the case linking global release of chlorofluorocarbons to episodic disappearance of ozone from the Antarctic stratosphere each austral spring? Three lines of evidence defining a link are (i) observed containment in the vortex of ClO concentrations two orders of magnitude greater than normal levels; (ii) in situ observations obtained during ten high-altitude aircraft flights into the vortex as the ozone hole was forming that show a decrease in ozone concentrations as ClO concentrations increased; and (iii) a comparison between observed ozone loss rates and those predicted with the use of absolute concentrations of ClO and BrO, the rate-limiting radicals in an array of proposed catalytic cycles. Recent advances in our understanding of the kinetics, photochemistry, and structural details of key intermediates in these catalytic cycles as well as an improved absolute calibration for ClO and BrO concentrations at the temperatures and pressures encountered in the lower antarctic stratosphere have been essential for defining the link.

Mycorrhizal mediation of plant response to atmospheric change: Air quality concepts and research considerations

The term ‘global climate change’ encompasses many physical and chemical changes in the atmosphere that have been induced by anthropogenic pollutants. Increases in concentrations of CO 2 and CH 4 enhance the ‘greenhouse effect’ of the atmosphere and may contribute to changes in temperature and precipitation patterns at the earth's surface. Nitrogen oxides and SO 2 are phytotoxic and also react with other pollutants to produce other phytotoxins in the troposphere such as O 3 and acidic substances. However, release of chlorofluorocarbons into the atmosphere may cause depletion of stratospheric O 3, increasing the transmittance of ultraviolet-B (UV-B) radiation to the earth's surface. Increased intensities of UV-B could affect plants and enhance photochemical reactions that generate some phytotoxic pollutants. The role of mycorrhizae in plant responses to such stresses has received little attention. Although plans for several research programs have acknowledged the importance of drought tolerance and soil fertility in plant responses to atmospheric stresses, mycorrhizae are rarely targeted to receive specific investigation. Most vascular land plants form mycorrhizae, so the role of mycorrhizae in mediating plant responses to atmospheric change may be an important consideration in predicting effects of atmospheric changes on plants in managed and natural ecosystems.

Do Medical CFCs Threaten the Environment?

ABSTRACT Today there is no doubt that chlorofluorocarbons (CFCs) are harmful to the atmosphere by damaging the stratospheric ozone layer and also acting as very potential greenhouse gases thus contributing to the global warming of our planet. For many years these compounds - especially Fll and F12 - have been used as propellants in pressurized cans and sprays, as refrigerants, as foam - blowing agents, as cleaning agents in the electronics industry etc. The estimated worldwide consumption of CFCs for 1988 is above 109 kg. After the environmental threats became obvious many more or less effective national and international actions were taken to reduce the release of CFCs into the atmosphere. Within the last years substitutes were developed for most purposes, especially also for commercially used pressurized spray cans. For metered dose inhalers CFCs at present cannot be fully replaced because of their physical, chemical and toxicological properties. Since the percentage of CFCs used for medical purposes is...

Optimum spectral resolution for computing atmospheric heating and photodissociation rates

Rapid, reliable and accurate computations of atmospheric heating rates are needed in climate models aimed at predicting the impact of greenhouse gases on the surface temperature. Photolysis rates play a major role in photochemical models used to assess potential changes in atmospheric ozone abundance due to man's release of chlorofluorocarbons. Both rates depend directly on the amount of solar radiation available at any level in the atmosphere. We present a very efficient method of computing these rates in which integration over the solar spectrum is reduced to a minimum number of monochromatic (or pseudogray) problems by appealing to the continuum features of the ozone absorption cross-sections. To explore the resolutions needed to obtain adequate results we have divided the spectral range between 175 and 700 nm into four regions. Within each of these regions we may vary the resolution as we wish. Accurate results are obtained for very coarse spectral resolution provided all cross-sections are averaged by weighting them with the solar flux across any bin. By using this procedure we find that heating rate errors are less than 20% for all altitudes when only four spectral bands across the entire wavelength region from 175 to 700 nm are used to compute the heating rate profile. Similarly, we find that the error in the photodissociation of ozone is less than a few percent when 10 nm resolution is used in the Hartley and Huggins bands (below 330 nm), while an average over the entire wavelength region from 400 to 700 nm yields similar accuracy for the Chappuis band. For integrated u.v. dose estimates a resolution slightly better than 10 nm is required in the u.v.B region (290–315 nm) to yield an accuracy better than 10%, but we may treat the u.v.A region (315–400 nm) as a single band and yet have an accuracy better than 2%.

Preliminary assessment of the greenhouse warming implications of halocarbon substitutes for CFC-11 and CFC-12

The contributions to future surface temperature forcing of halocarbons (HCFCs) proposed to replace the chlorofluorocarbons (CFCs) CFC-11 and CFC-12 under the terms of the Montreal Protocol agreement have been assessed. Implementation of controls on the production, use and release of CFCs is predicted to reduce warming significantly. Computed temperature increases are sensitive to the assumed growth rates of CFC-11 and CFC-12 over the next 30 years, but thereafter the effects due to the possible substitutes HCFC-142b and HFC-134a become increasingly important. While the possible substitutes HCFC-123 and HCFC-141b are found to have a smaller warming influence, it is expected that HCFC-22 will assume a major future warming role, unless its anticipated production growth rate is reduced.

Kinetics of O3 destruction by ClO and BrO within the Antarctic vortex: An analysis based on in situ ER‐2 data

Simultaneous, in situ observations of ClO, BrO, O3, N2O, pressure, and temperature are used to examine the kinetics of ozone destruction within the Antarctic polar vortex. The high azimuthal symmetry of the vortex is used to simplify the problem such that the time rate of change of ozone on isentropic surfaces between 450 and 360 K (18.3‐ to 13.5‐km geometric altitude) can be calculated based on proposed catalytic cycles involving ClO, BrO, HO2 and O(3P). The availability of simultaneous, spatially resolved data on N2O, pressure, and temperature is used to reduce scatter in observed O3; this clarifies the quantitative analysis of ozone loss rates on isentropic surfaces. The kinetics of ozone destruction is thus cast in an N2O‐potential temperature coordinate system to suppress atmospheric variability. We conclude, based upon observed radical concentrations and the most recent laboratory kinetics data, that the chlorine dimer mechanism (Molina and Molina, 1987) rate limited by ClO + ClO + M → ClOOCl + M, referred to herein as mechanism I, constitutes the largest single contribution to the integrated rate of ozone destruction within the vortex on isentropic surfaces between altitudes of 14 and 18.3 km. We find that approximately 40% of the observed ozone loss rate in this altitude interval results from this mechanism, using the recently established pressure and temperature dependence for the rate of dimer formation reported by Sander et al. (1989). The coupled bromine‐chlorine catalytic cycle (McElroy et al., 1986) rate limited by ClO + BrO → Cl + Br + O2 (herein mechanism II) constitutes approximately 20% of the ozone loss rate integrated over the course of the mission, August 23 to September 22, 1987. Mechanism III, suggested by Solomon et al. (1986), which is rate limited by ClO + HO2 → HOCl + O2 (in close competition with OH + O3 → HO2 + O2), constitutes 4% of the observed ozone loss rate based on observed ClO, but calculated HO2 concentrations. We find that the time‐honored catalytic coupled ClO + O → Cl + O2 followed by Cl + O3 → ClO + O2, identified by Molina and Rowland (1974) as the key reaction linking chlorofluorocarbon release to middle‐ and low‐latitude stratospheric ozone depletion, constitutes 3% of the observed loss in the Antarctic vortex. The sum of all four mechanisms thus constitutes 65% of the observed O3 loss with an experimental uncertainty of ±30%. An array of other halogen‐oxygen radical catalytic cycles are considered. The manifold of possible catalytic cycles is large, particularly when the temperature and pressure regime characteristic of the Antarctic lower stratosphere is considered. Quantitative analysis is impeded primarily by the absence of laboratory data on key reaction rates. For example, a potentially critical alternative channel, designated herein as mechanism V, is the termolecular process ClO + O3 + M → ClO · O3 + M, followed by photolysis, for which no kinetic data exist. Explicit note is also taken, in the quantitative conclusions, of the ozone flux divergence within the chemically perturbed region reported by Hartmann (1989). This constitutes an additional 20±10% requirement on the rate of chemical removal.

Ozone destruction by chlorine radicals within the Antarctic vortex: The spatial and temporal evolution of ClO‐O3 anticorrelation based on in situ ER‐2 data

In situ O3 and ClO data obtained from the ER‐2 aircraft are used to define the chemical evolution of the Antarctic vortex region from August 23 to September 22, 1987. Initial conditions are characterized at aircraft flight altitude (18 km) by highly amplified ClO mixing ratios (800 parts per trillion by volume (pptv)) within a well‐defined “chemically perturbed region” (CPR) poleward of the circumpolar jet, within which ozone exhibits limited erosion (∼15%) in middle to late August. Within this CPR, ozone decays consistently throughout the course of a 10‐flight series, such that by late September, 75% of the O3 has disappeared within the region of highly amplified ClO concentrations (which reached 500 times normal levels at ER‐2 cruise altitude). As this ozone depletion develops, O3 and ClO exhibit dramatic negative correlation on isentropic surfaces, obtained as the aircraft passed through the edge of the CPR. Taken in conjunction with an analysis of the mechanisms defining the rate of catalytic O3 destruction, it is concluded that ClO is an essential constituent in the catalytic destruction of ozone within the vortex. Therefore it is concluded that the observed disappearance of ozone within the Antarctic vortex would not have occurred in the absence of global chlorofluorocarbon release.