Annual Variations

Usually the annual variations in the specific resistance of the soil lead only to small changes in the current circuit resistance so that adjustment of the protection... 

Seasonal variations are associated not only directly with the elevation of the sun, but also with changes of surface currents depending on the prevailing winds. The annual variation is generally quite small in the tropics and greatest in the temperate zones, where it may amount to about 10° C. 

Dorr, H. and Miinnich, K. O. (1987). Annual variation in soil respiration in selected areas of the temperate zone, Tellus, Ser. B, 39,114-121. 

Ormerod, S.J. and S.J. Tyler. 1994. Inter- and intra-annual variation in the occurrence of organochlorine pesticides, polychlorinated biphenyl congeners, and mercury in the eggs of a river passerine. Arch. Environ. Contam. Toxicol. 26 7-12. 

As well as daily variations in flow rate and concentration there are also annual variations. These can be simulated by assigning a variable function to the value of Fav. For instance, the following sine function could be used ... 

Figure 8.1 Annual variation in atmospheric carbon dioxide concentration as recorded at the Mauna Loa Observatory, Hawaii.

Figure 21.5 Response of linear system to external periodic perturbation (Eq. 21-12). Full lines show hypothetical steady-state (Eq. 21-19) dashed lines give system response (Eq. 21-18). The system rate constant k = 4.0 yr 1 corresponds to the behavior of PCE in Greifensee (Box 21.2). Curve A corresponds to an annual variation with relative amplitude Aj = 0.5, curve B to a variation with period of 4 years and A, = 1.

The point of reference is chosen as x0 = 30 m. The angular frequencies for the diurnal, monthly, and annual variations are, respectively ... 

Both water temperature and PCE concentration show a clear annual variation. The maximum (minimum) water temperature is registered in the first well about 18 days earlier than in the second one, and the temperature amplitudes are approximately equal in both wells. In contrast, the time lag observed for the concentration variation of PCE between the two wells is 6 months. The concentration amplitude of PCE in the downstream well, that is, the difference between maximum and mean concentration, is only about 65% of the amplitude in the upstream well, but the annual mean concentrations are equal in both wells. 

Napela, T. F., J. F. Cavaletto, M. Ford, W. M. Gordon, and M. Wimmer, Seasonal and annual variation in weight and biochemical content of zebra mussel, Dreissena polymorpha in Lake St. Clair , J. Great Lakes Res., 19, 541-552 (1993). 

In order to use aerosol optical depth typical values for the Portuguese territory, monthly average values of a and p were estimated for each station and for the whole observation period. Finally, the final average value used was estimated from the average of the 4 stations. Figures 1 and 2 show the annual variation of P e a, respectively, for the 4 sites. 

Figure t. Average annual variation of /i coefficientfor Braganqa. Penhas Douradas. Lisboa/Gago Coutinho and Sines stations from 1977 to 1986. 

Estimation of average values for Portugal mainland was improved by adjustment of the estimated values to the annual variation observed at Lisbon Dobson station (1975 a 1997). 

It has been known for about 50 years4 that the annual variations in ozone do not correspond to these of the solar radiation depending on the latitude and the season. The behavior of ozone is characterized by a maximum in spring and a minimum in autumn also there is more ozone at high than at low latitudes. This behavior shows that the chemical reactions in question are slow, in comparison with transport phenomena, in the lower stratosphere below 25 km. 

Figure 5.8 Daily and annual variations in ambient air wet-bulb temperatures.

Several European intensive short-term ( campaign-type ) projects have provided important information on the atmospheric aerosol properties in Europe, usually by concentrating on specific aerosol properties or interactions. However, these kinds of campaign-type measurements do not necessarily represent the seasonal or annual variations of the aerosol concentrations and can overestimate some properties of the aerosol populations. Long-term measurements, especially with intercalibrated instruments and common data handling and calibration protocols make the data comparison between stations much more reliable and provide the end users (e.g., atmospheric modelers) good datasets to compare with. 

In addition to long-term and large-scale climatic effects, the annual variation in weather conditions also affected the amount and turnover of plant residues and thus the chemical composition SOM sampled at a certain date (Leinweber et al., 1994, 1995). Figure 14.19 shows the ion intensities for carbohydrates in two plots of the Eternal Rye Cultivation experiment at Halle, Saxony-Anhalt, Germany. In 1958, parts of the former rye monoculture were shifted into maize monoculture. This resulted in decreases in the ion intensities for carbohydrates. In the plot that remained under rye monoculture the ion intensities for carbohydrates increased initially. For several time periods, the changes in ion intensities were roughly parallel for the two plots, which is considered as evidence for annual variations in the decomposition dynamics. For some time (1993 to 1997), there was no significant difference between the rye and maize plots in the ion intensities for carbohydrates, but the... 

Figure 14.19. Long-term changes and annual variation in the proportions of carbohydrates of the unfertilized plot grown with rye and maize after previously rye from the Eternal Rye Cultivation experiment at Halle/Saxony-Anhalt, Germany.

Figure 72 Annual variations in the lipid content of sprat of different sizes. Fish were caught in June or July. (After Minyuk, 1991.)...

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