Some Meteorological Aspects

These are the most familiar. Most television transmitters, for instance, broadcast a satellite photograph to illustrate the announcer s commentary in the weather forecast. Indeed, research studies are so plentiful that it would be impossible to select a brief bibliography. 

The satellites are meteorological, and when they are operational, like the ESSA, they work exclusively on weather-forecasting, using TV and infrared imageries, automatically restored to scale. 

Fundamental research is facilitated chiefly by other instruments on board the experimental satellites when infrared is analyzed, it is in the form of digitized maps, which are not available until about a year later. 

Every day, photographic mosaics are made up from all orbits and from television and infrared data, giving a worldwide picture of the distribution of cloud masses, fronts, and atmospheric perturbations. With the ESSA and Nimbus, we have four shots available per 24 h (9 00 and 21 00 for ESSA, 12 00 and 24 00 for Nimbus). Thus, forecasts can be made with an accuracy unknown before the space age. 

Another aspect of meteorological observation is shown in photo 2, Plate D, opposite p. 81. Complete global coverage is provided by two stationary satellites, one over the Pacific, the other the Atlantic. Every 30 min, we receive a worldwide picture, considerably facilitating observation of all atmospheric movements. Speeded-up cartoon films have been made of these movements for teaching purposes for instance, we were able to follow the pattern of the jet stream for the first time on the screen. 

---

The meaning of the the term "hybrid receptor model" is not consistent in the literature. Following the definition proposed at the Quail Roost Receptor Modeling Workshop (15), we take it to be a combination of some meteorological aspects of traditional source-based models with some tracer aspects of receptor models. An important feature of such models is that one often works with ratios of species so that some of the most uncertain absolute parameters of classical models cancel out. As noted below, for example, one can calculate the concentration ratio of gas-phase SO2 to gas-phase B as a function of distance from a common source more accurately than the absolute concentration of either species. 

The literature contains reviews of air quality modeling that stress special purposes. Some concentrate on meteorologic aspects, and others combine this with air chemistry. Proceedings of several conferences are another information resource. Recent surveys have been addressed specifically to photochemical modeling problems. It may be concluded that, although they are relatively complex, the photochemical-diffusion models perform as well as, if not better than, available inert-species models. 

The early checkout of the model and the results in testing the improvements we attempted in the chemical, mathematical, and meteorological aspects of the problem are summarized below. Many times it seemed that the earlier simple concepts gave better results, but working with better data and more demanding theoretical descriptions than before, we uncovered some significant areas to investigate further. 

Machta, L., Some aspects of the USA fallout programme. Meteorological aspects of atmospheric radioactivity. World Meteorological Organisation, Geneva, Tech. Note No. 68, pp. 155-177 (1965). 

Another aspect of matching output to user needs involves presentation of results in a statistical framework—namely, as frequency distributions of concentrations. The output of deterministic models is not directly suited to this task, because it provides a single sample point for each run. Analytic linkages can be made between observed frequency distributions and computed model results. The model output for a particular set of meteorologic conditions can be on the frequency distribution of each station for which observations are available in sufficient sample size. If the model is validated for several different points on the frequency distribution based on today s estimated emission, it can be used to fit a distribution for cases of forecast emission. The fit can be made by relating characteristics of the distribution with a specific set of model predictions. For example, the distribution could be assumed to be log-normal, with a mean and standard deviation each determined by its own function of output concentrations computed for a standardized set of meteorologic conditions. This, in turn, can be linked to some effect on people or property that is defined in terms of the predicted concentration statistics. The diagram below illustrates this process ... 

The vertical structure of PBL and SL is very important for ACTMs, so increasing the vertical resolution and improved parameterizations of BL are necessary. The meteorological improvements are already worked out for some aspects (stable PBL) and the urban characteristics should be included in the new surface scheme. In the meso-scale model the urban parametrization is already available (TEB Town Energy Budget in SURFEX and BEP Building Effect Parameter-isation in Enviro-HIRLAM). 

To highlight some of the points discussed in this section, certain aspects of the assessments of the TMI-2 accident merit discussion. Figure 5.2-10 presents the hourly wind vector as measured by the site meteorological system during the first day of the accident. Actually, these measurements were not available to the NRC until three days later because the plant computer crashed early in the accident. It is evident that wind direction at the site varied dramatically throughout the 12-hr period. 

---