Measurement station

Measurement station Element inserted in ductwork or pipework to facilitate the determination of temperature, humidity, flow rate, and/or pressure. 

When these are close together, most of the simultaneously measured velocities will relate to fluid in the same eddy and the correlation coefficient will be high. When the points are further apart the correlation coefficient will fall because in an appreciable number of the pairs of measurements the two velocities will relate to different eddies. Thus, the distance apart of the measuring stations at which the correlation coefficient becomes very poor is a measure of scale of turbulence. Frequently, different scales of turbulence can be present simultaneously. Thus, when a fluid in a tube flows past an obstacle or suspended particle, eddies may form in the wake of the particles and their size will be of the same order as the size of the particle in addition, there will be larger eddies limited in size only by the diameter of the pipe. 

Another problem encountered when registering precipitation in mountainous regions is the spatial distribution of measurement stations (e.g. [26]). The volume and intensity of precipitation in mountainous regions is highly variable even over small areas. Yet these very regions often suffer from a lack of dense precipitation measurement networks, since measurement stations are mainly to be found in valleys. Consequently, up to now the data collected in order to measure the spatial variability and volume of precipitation in higher-altitude regions has been insufficient. 

Fig. 11 illustrates this hydrological paradox [37] by comparing the altitude distribution of runoff measurement stations in Switzerland and Nepal Nepal, a key hydrological mountainous country for the Indian subcontinent (cf. Sect. 5), has only... 

Fig. 11 Frequency of runoff measurement stations per altitude level (status 2005), Left = Switzerland, Right = Nepal (based on [38, 80])...

It is apparent from the above that only very few catchment areas in alpine regions have access to runoff data. Consequently, regionalization procedures need to be developed and applied for the purpose of estimating runoff characteristics [42]. In turn, however, the value of such estimates depends on the runoff data available for calibrating these models. This gives rise to the same dilemma mentioned above in connection with mnoff measurement networks In alpine regions with few runoff measurement stations it will be difficult to develop effective regionalization approaches. 

Fig. 19 Spatial representation of low water seasonality for selected runoff measurement stations [85]...

In addition to measurement stations and reaches of river where affected runoff regimes occur. Fig. 3 also shows measurement stations and reaches of river in which hydropeaking characteristics have been identified [19, 20]. It also shows river reaches which have been dammed for use by run-of-river power plants. The presentation is limited to larger rivers in Switzerland. 

Air flow diagrams for air handling unit components show, in proper sequence, flow measuring stations, reheat coils, location of each filtration level, humidifiers, exhaust fans and other system components. 

For long-lived atmospheric species a limited number of measurement stations around the globe may provide an adequate monitoring networic. However, for short-lived species and species having sources that are variable in time and space, the global measurement of concentrations can best be made from remote sounding instrumentation aboard orbiting space-based platforms. 

Void volume based on the elevation-change contours and the area enclosed by the dashed line in Figure 3 was calculated to be nearly 150 cu ft. The total area affected by explosive fracturing could not be determined because of the lack of elevation-measuring stations outside of the contoured area. 

In modern high-technology situations, however, very high reproducibilities are frequently required. A good metrological system must provide means whereby any measurement station can have access to the highest needed level of the system. 

A procedure of this kind was used in the International Odra Project—IOP (1997-2001).113 Screening tests of water samples on V. fischeri bacteria showed that samples taken from two measuring stations (the town of Brzeg Dolny and the confluence of the Mala Panew River with the Odra River, Poland) were toxic toward the bacteria. Chemical analysis for the detection of organic... 

During the first European Tracer Experiment (ETEX-1) a non-depositing tracer gas (Perflouro-Methyl-Cyclo-Hexane) was emitted from a site in Northern France (Brittany (2°00 30", 48°03 30")). The average emission rate was 7.95 g s and it commenced on 23 October at 16 00 UTC lasting for 11 h and 50 min. The spatial and temporal development of the tracer cloud was measured at 168 measurement stations in Europe and both real time and retrospective model inter-comparison projects were carried out (Graziani et al. 1998 Mosca et al. 1998). The purpose of this experiment was to evaluate the models ability to transport and disperse a tracer. 

The current version of Enviro-HIRLAM has not previously been evaluated against ETEX-1 measurements. The ETX domain (Eig. 5.1) was used with at time-step fixed at 10 min, and initial and boundary conditions were post-processed from the European Centre for Medium-Range Weather Eorecasts operational model, IFS (Integrated Forecast System). No surface or upper air data assimilation was employed and the model was integrated 80 h into the future. The start time was on 23 October 1994 at 12 00 UTC, 4 h before the start of the release. Output was interpolated to measurement stations in order to compare to the observations and produce statistical measures. 

Table 5.1 Statistical scores for the ETEX-1 simulation at 11 selected measurement stations...

The set-up is identical to what is described in the evaluation of transport and dispersion section. The output has been interpolated to two ETEX-1 measurement stations, E15 and DK02, which were dominated by short and long range transport respectively. 

Mexico City suffers from severe air quality problems with maximum ozone values up to 250 ppb. In order to study the effect of different precursor emissions and possible mitigation measures on the ozone levels in Mexico City the MCCM was applied in the Greater Area of the city (Jazcilevich et al. 2003 Forkel et al. 2004). Figure 7.4a shows that, in agreement with observations, the simulated O3 maxima occur in the southwest of the city (measurement station FED), which is down-wind of the city centre, as an uphill flow is prevailing during the afternoon. The minimum ozone concentrations are found in the centre of the city (station MER), where the NO emitted by traffic titrates the ozone, and in the northern part of the city at places where the NO emissions from industry and power plants locally reduce the ozone concentrations (near station XAL). 

Fig. 17.2 Observed bold solid lines) and modeled dotted lines) surface CO mixing ratio at measurement stations (a) Minamitorishima (24.2°N, 153.6°E), (b) Yonagunijima (24.3°N, 123.1°E), and (c) Ryori (39.2°N, 141.5°E). Regional tagged CO tracers for northern China and Korea, southern China, south Asia, Europe, North America, and chemically production dotted lines) are also shown...

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