The atmospheric record

The data in Fig. 7.1 cover the period during which reliable analytical techniques have been in use. In order to extend the record further into the past, resort is made to measurements obtained using cruder techniques (by modern-day standards) in the latter part of the f 9th century and the first half of the 20th century. These early data are shown in Fig. 7.2, together with the most complete recent dataset, which is from Mauna Loa. A more reliable way of extending the record backwards has been through the extraction and analysis of bubbles of air trapped in ice cores collected from the polar ice-caps. The principle of this method is that the trapped air bubbles record the atmospheric composition at the time the ice formed. By dating the various layers in the cores from which the air bubbles have 

Although the trend of atmospheric C02 concentrations is clearly upward in Fig. 7.1, the increase is only about half of what would be expected if all the C02 from fossil fuel burning since 1958 had remained in the atmosphere, as shown in Fig. 7.8. This indicates that the half that does not appear in the atmospheric record must have been taken up by some other environmental reservoir. This is a simplistic deduction since it assumes that the other reservoirs have themselves not changed in size and that they have not had net exchange with the atmosphere during the relevant period. Despite these simplifications, the calculation forces us to examine the other reservoirs and so stresses the importance of looking at the system as an entity, rather than as disconnected environmental compartments. 

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Add tap water to the beaker (or pail), or lift the cylinder, so that the water inside the cylinder is at exactly the same level as the water in the beaker. This equalizes the pressure in the cylinder with the pressure of the atmosphere. Record the volume of the gas collected when the water levels are equal inside and outside the cylinder. 

Leung, Colussi and Hoffmann have used isotopic analysis in an attempt to constrain the amount of sulfate that could be produced by Crutzen s mechanism [129,130]. The first study retrieved the concentration profiles of OC S and OC S from infrared transmission spectra of the atmosphere recorded by the NASA MkIV balloon-borne interferometer. They derived an enrichment factor of 73.8 zb 8.67oo defined such that photolytically generated sulfur would be enriched in An isotopic budget based on this result shows that OCS photolysis cannot be a significant source of sulfate aerosol, since the enrichments of OCS, sulfuric acid aerosol and SO2 are known to be small [131]. A later laboratory study by the same group came to the conclusion that stratospheric photolysis results in an enrichment of 67 zb 77oo. 

As with most foram records, the atmospheric record cannot be dated with radiometric techniques. Dating of the record has been accomplished by correlation with the orbitally tuned deep-sea record (Sowers et al., 1993), using estimates of ice accumulation rates, ice flow models, and estimates of offsets between snowfall and gas closure ages (Petit et al., 1999), and by direct orbital tuning of the atmospheric oxygen record itself (Shackleton, 2000). Separate tuning of the marine and atmospheric records establishes independent chronologies for the two. 

Figure 10 The atmospheric record in the Northern Hemisphere (solid line). Also shown are the modeled content of a homogenous, steady-state carbon pool with turnover times of 5 years and 50 years (Equation (7))...

Figure 3B shows detailed Pacific Ocean A " C coral ring data (J.R. Toggwelier and E. Druffel). This surface ocean record shows an increase during the 1960s however, the peak occurs somewhat later than in the atmosphere and is significantly less pronounced. Careful investigation of coral data also demonstrates the north-south difference evidenced in the atmospheric record. 

The averaging time of the rapid-response record [Fig. 4-1 (a)] is an inherent characteristic of the instrument and the data acquisition system. It can become almost an instantaneous record of concentration at the receptor. However, in most cases this is not desirable, because such an instantaneous record cannot be put to any practical air pollution control use. What such a record reveals is something of the turbulent structure of the atmosphere, and thus it has some utility in meteorological research. In communications... 

Where specialized fluctuation data are not available, estimates of horizontal spreading can be approximated from convential wind direction traces. A method suggested by Smith (2) and Singer and Smith (10) uses classificahon of the wind direction trace to determine the turbulence characteristics of the atmosphere, which are then used to infer the dispersion. Five turbulence classes are determined from inspection of the analog record of wind direction over a period of 1 h. These classes are defined in Table 19-1. The atmosphere is classified as A, B2, Bj, C, or D. At Brookhaven National Laboratory, where the system was devised, the most unstable category. A, occurs infrequently enough that insufficient information is available to estimate its dispersion parameters. For the other four classes, the equations, coefficients, and exponents for the dispersion parameters are given in Table 19-2, where the source to receptor distance x is in meters. 

It is the almost universal practice to record the nature and strength of an odour at the particular temperature which may obtain at the time of examination. Substances at their temperatures of boiling have a common vapour pressure equal to that of the atmosphere, but it is clearly impossible to smell a substance in such a condition, whereas, if we could go to the other extreme, the absolute zero, it is probable that no vapour would exist as such and for this reason alone, apart from any physiological one, no odour would be discernible. 

The exposure site is selected according to the service for which the data are to be applicable. For atmospheric service, such factors as marine and industrial contaminants, sunlight, dew and sand abrasion, must be considered. Atmospheric specimens are normally mounted at 45°, facing south. This has been shown to provide about a 2 1 acceleration of failure compared with a vertical exposure. Whether this or other standardised positions are used, the details of the exposure are an important part of the test record. 

The solar spectrum is, of course, as well studied as our planetary atmosphere will permit. More information will be forthcoming as spectra from man-made satellites are recorded above the atmosphere. At this time, the spectra of many diatomic molecules have been detected. These are not the familiar, chemically stable molecules we find on the stockroom shelf. These are the molecules that are stable on a solar stockroom shelf. Figure 25-3 shows some of these and the location in the periodic table of the elements represented. 

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