Climate atmospheric particles

A controversy with possibly far-reaching consequences concerns the impact of atmospheric particles on the earth s climate. Temperature is one of the most easily monitored indicators of climatic change. Among the many discussions of the effects of aerosols on the global mean temperature, we direct the reader to the monograph by Twomey (1977) and the paper by Toon and Pollack (1980), from which some of the following is taken. 

Among the reasons it is difficult to predict the effect of particles on climate is that their composition and distribution are poorly known. The main types of known atmospheric particles are listed in Table 14.1. 

Direct measurement of absorption and backscattering at a sufficient number of sites to obtain a representative global average would be a step in the right direction toward assessing the impact of atmospheric particles on climate. 

It seems that we have cast atmospheric particles most often in the role of villains they may cause cataclysmic climatic changes they reduce visibility they may aid in the formation of photochemical smog and acid rain. But there is a scheme afoot to make them do some useful work by acting as ubiquitous retro-reflectors for laser beams. 

Both settle-able and suspended atmospheric particles have deleterious effects upon the environment. The scttlc-able partidcs can affect health if assimilated and also can cause adverse effects on materials, crops, and vegetation. Further, such partides settle out in streams and upon land where soluble substances, sometimes including hazardous materials, are dissolved out of the particles and thus become pollutants of soils and surface and ground waters. Suspended atmospheric particulate matter has undesirable effects on visibility and, if continuous and of sufficient concentration, possible modifying effects on the climate. Importantly, it is particles within a size range from 2 to 5 micrometers and smaller that are considered most harmful to health because particles of this size tend to penetrate the body s defense mechanisms and reach most deeply into the lungs. 

Atmospheric particles influence the Earth climate indirectly by affecting cloud properties and precipitation [1,2], The indirect effect of aerosols on climate is currently a major source of uncertainties in the assessment of climate changes. New particle formation is an important source of atmospheric aerosols [3]. While the contribution of secondary particles to total mass of the particulate matter is insignificant, they usually dominate the particle number concentration of atmospheric aerosols and cloud condensation nuclei (CCN) [4]. Another important detail is that high concentrations of ultrafine particles associated with traffic observed on and near roadways [5-7] lead, according to a number of recent medical studies [8-11] to adverse health effects. 

Size distributions of atmospheric particles Sources and sinks of atmospheric particles Visibility reduction Radiative forcing and climate change Health effects... 

Today, the anthropogenic emissions of SO, primarily from fossil fuel combustion, largely dominate the sulfur flux into in the atmosphere on the global scale. Climate models have determined the corresponding direct and indirect impacts on radiative forcing, but large uncertainties remain in these estimates. In fact, predictions of future climate need to account not only for the effects of sulfate aerosols, but also for the contributions of mineral dust, black carbon, organic carbon, and sea salt. The current view is that atmospheric particles should be treated as multicomponent, mul-... 

Quantities of airborne particles in industrialized regions of the Northern Hemisphere have increased markedly since the Industrial Revolution. Atmospheric particles (aerosols) arise both from direct emissions and from gas-to-particle conversion of vapor precursors. Aerosols can affect climate and stratospheric ozone concentrations and have been implicated in human morbidity and mortality in urban areas. The climatic role of atmospheric aerosols arises from their ability to reflect solar radiation back to space and... 

Water is abundant on our planet, distinguishing Earth from all other planets in the solar system. More than 97% of Earth s water is in the oceans, with 2.1% in the polar ice caps and 0.6% in aquifers. The atmosphere contains only about one part in a hundred thousand (0.001%) of Earth s available water. However, the transport and phase distribution of this relatively small amount of water (estimated total liquid equivalent volume of 13,000 km3) are some of the most important features of Earth s climate. The existence of varying pressures and temperatures in the atmosphere and at the Earth s surface causes water to constantly transfer among its gaseous, liquid, and solid states. Clouds, fogs, rain, dew, and wet aerosol particles represent different forms of that water. Aqueous atmospheric particles play a major role in atmospheric chemistry, atmospheric radiation, and atmospheric dynamics. 

Seidl, W. and G. Hanel (1983) Surface-active substances on rainwater and atmospheric particles. Pure and Applied Geophysics 121, 1077-1093 Seiler, W., and P. X Crutzen (1980) Estimates of gross and net fluxes of carbon between the biosphere and the atmosphere from biomass burning. Climatic Change 2, 207-247 Seiler, W., R. Conrad and D. Scharffe (1984) Eield studies of methane emission from termite nests into the atmosphere and measurements of methane uptake by tropical soils. Journal of Atmospheric Chemistry 1, 171-186... 

The Earth s atmosphere is a two-phase system consisting of gases and particles (solid or hquid). This means the entire atmosphere is, by definition, an aerosol. The number concentration and size distribution of environmental or atmospheric aerosol particles are highly variable in space (marine and continental, or boundary layer and Iree troposphere) and time (summer and winter). Although the total mass of these particles is small compared with the total mass of atmospheric gases, atmospheric particles play an important role in today s research on climate change, air pollution, and human health. 

Clouds cover roughly two-thirds of our earth s surface and play an important role in influencing global climate by affecting the radiation budget. Cirrus clouds are one example of a cloud type whose optical properties are not accurately known. Cirrus clouds form in the upper troposphere and are composed almost exclusively of non-spherical ice crystal particles. The impact of cloud coverage on dispersion of pollution in the atmosphere is an area of great concern and intensive study. 

Climate is often viewed as the aggregate of all of the elements of weather, with quantitative definitions being purely physical. However, because of couplings of carbon dioxide and many other atmospheric species to both physical climate and to the biosphere, the stability of the climate system depends in principle on the nature of feedbacks involving the biosphere. For example, the notion that sulfate particles originating from the oxidation of dimethylsulfide emitted by marine phytoplankton can affect the albedo (reflectivity) of clouds (Charlson et ai, 1987). At this point these feedbacks are mostly unidentified, and poorly quantified. 

Aerosol spray cans were invented in 1929, and perfection of a reliable valve and development of disposable cans took place in the 1940s. Shortly thereafter, aerosol became a household word. Like many other modem conveniences, however, the aerosol spray can has drawbacks as well as advantages. Because the particles in an aerosol are extremely tiny, they are quite mobile. They last for a long time in the atmosphere and can affect the climate, as already described. They can penetrate deep into our lungs and cause adverse health effects. Thus, anthropogenic aerosols have both global and local side effects. Despite increasing scientific studies, these effects are not yet fttlly understood. 

The chemistry of carbon, and radiocarbon, in the atmosphere represents one of the most important areas of environmental research today. The primary practical reason for this is the increasing attention which must be paid to the critical balance between energy and the environment, especially from the viewpoint of man s perturbations of natural processes and his need to maintain control. Probably more than other species, carbonaceous molecules play a central role in this balance. Some of the deleterious effects of carbonaceous gases and particles in the atmosphere are set down in Table 3. The potential effects of increased local or global concentrations of these species on health and climate have led to renewed interest in the carbon cycle and the "C02 Problem". It should be evident from the table, however, that carbon dioxide is not the only problem. In fact, the so-called "trace gases and particles" in the atmosphere present an important challenge to our interpretation of the climatic effects of carbon dioxide, itself [20]. 

This is an area of strong continental climate with dry and hot summer and severe winter with strong winds that transport dust at short and long distance, for instance yellow sand phenomenon in northwest China. During air transport these soil particles absorb numerous pollutants-carcinogens, like benzo(a)pyrene and heavy metals (Ni, Cd, Co, Zn, Pb, As) both from industrial emissions into the atmosphere and waste landfill sites. 

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