Isopleths

Fig. 2. Examples of ozone isopleths generated using four different chemical mechanisms (a) EPA (b) ESM (c) CBII (d) ELSTAR NMOC = nonmethane...

Fig. 3. Typical isopleth diagram showing the three chemical regimes HC = hydrocarbons (22).

Fig. 28. Isopleth in Al—Cu—Mg—Zn system where the appropriate ratio is CuMg Zn = 1 1.4 3.3.

Fig. 8. isopleth diagram showing the response of concentrations to changes in initial NO and nonmethane hydrocarbon concentrations expressed as parts per million of carbon atoms (ppm C). The response to NO reductions is dependent on the particular initial concentrations. At point A, the graph indicates that decreasing NO would increase formation, and at point C, a decrease in the NO concentration results in a much larger decrease in... 

A typical reqmrement is to determine the cloud boundaiy at a fixed concentration. These boundaries, or lines, are called isopleths. The... 

Set C)(x,y,0,t) = in Eq. (26-62) and determine the value of y at each centerhne point determined in step 2. Plot the y values to define the isopleth, using symmetry around the centerline. 

A method for graphically displaying individual risk results is use of the risk contour, or risk isopleth. If individual risk is defined as the likelihood of someone suffering a specified injury or loss, then individual risk can be calculated at particular geographic locations around the vicinity of a facility or operation. If the individual risk is calculated at many points surrounding the facility, then points of equal risk can be connected to... 

Fig. 15-S. Concentration isopleth diagram of ambient particulate matter calculated by a computer model. Source Zimmer, C. E., "Air Pollution," 3rd ed., Vol. Ill (A. C. Stem, ed.). Academic Press, New York, 1976.

Pollutant concentration maps may be constructed as shown in Fig. 15-5 (14). In this example, elevated levels of ambient particulate matter are associated with population centers. For a given geographic area, isopleths, lines showing equal concentrations of a pollutant, are drawn on a map. Regions of high concentration are quickly identified. Further action may be taken to determine the cause, such as review of emission inventories of additional sampling. 

For administrative purposes, it is desirable that the boundaries of an air quality control region be the same as those of major political jurisdictions. Therefore, when the first air quality control regions were officially designated in the United States by publication of their boundaries in the Federal Register, the boundaries given were those of the counties all or part of which were within the background concentration isopleth. 

Isopleth a line drawn on a map through all points having the same numeric value. Isotropic a situation where a quantity (or its spatial derivatives) is independent of position or direction. 

Primarily models chemical releases to the air. Includes a chemical database and map editor and is capable of mapping concentration isopleths. Allows real-time meteorological data input. 

We have previously examined the mutual dependence of [HO ] upon [NO,jj and [NMHC] as calculated by a combined clean/polluted air chemical mechanism (76), and extend those calculations here to the more modem CAL mechanism of Lurmann et al. (182). To do this we have combined the NO,/NMHC chemical reactions of the CAL mechanism with the methane chemistry of Logan et al. (58). The results of these calculations are shown as contour maps or isopleths for [O3], [HO ], and [HO2 ] in Figure 7. Figure 7a, for ozone, is similar to isopleths used to determine reductions in NMHC and/or... 

Figure 7. Ozone, hydroxyl, and hydroperoxyl isopleths calculated using a combined clean/polluted air chemical mechanism. A. [O3] contours, ppb. B. [HO.] contours, 10 molecules cm . C. [H02 ] contours, 10 molecules cm Contours are maximum concentrations achieved in one day exposure to sunlight from starting [NMHC] and [NOJ concentrations on axes.

Each isopleth describes the maximum species concentration achieved during the simulation. In all isopleths, the contours are horizontal at the left-hand edges, indicating that NMHC starting concentrations were reduced sufficiently so that they did not affect the calculated concentration of the species displayed. 

Figure 4 shows an isomap of the lead pollution in the first smelter area of the Dallas Lead Study. The round symbol in the center represents the smelter. The lines are isopleths of lead in soil in pg/g. Note the cluster of closed isopleths encircling the smelter. The large number of concentric isopleths encircling the smelter shows a steep gradient or rapid change in a short distance between a low (200 ig/g) outside and a high (3,000 pg/g) inside. 

Figure 1. Isopleths of krlglng estimation variances. (The bull s-eyes reflect the data locations.)...

Figure 3. Isopleth maps of the concentration estimate and the associated probability (1 - a(x)) to make a correct decision to clean.

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