Temporal variability

The inherent temporal variability of climate thus obscures the search for long-term climatic signals. In addition, the search is plagued by the great spatial variability of climatic change. 

In fluid reservoirs like fhe afmosphere or the ocean, the turnover time of a tracer is also related to the spatial and temporal variability of ifs concentration within the reservoir a long turnover time corresponds to a small variability and vice versa (Junge, 1974 Hamrud, 1983). Figure 4-2 shows a plot of measured trace gas variability in the atmosphere versus turnover time estimated by applying budget considerations as indicated by Equation (1). An inverse relation is obvious, but the scatter in the data... 

Peltzer, E. T. and Hayward, N. A. (1996). Spatial and temporal variability of total organic carbon along 140 W in the equatorial Pacific Ocean in 1992. Deep-Sea Res. II43, 1155-1180. 

Figure 2 Pesticide stream concentrations, 1994-2002 (demonstration of temporal variability in concentrations)...

Duime JP, Murray JW, Rodier M, Hansell DA (2000) Export flux in the western and central equatorial Pacific zone and temporal variability. Deep-Sea Res 147 901-936 Eppley RW, Peterson BJ (1979) Particulate organic matter flux and planktonic new production in the deep ocean. Nature 282 670-680... 

McKee BA, DeMaster DJ, Nittrouer CA (1984) The use of Th-234/U-238 disequilibrium to examine the fate of particle-reactive species on the Yangtze continental shelf. Earth Planet Sci Lett 68 431-42 McKee BA, DeMaster DJ, Nittrouer CA (1986) Temporal variability in the portioning of thorium between dissolved and particulate phases on the Amazon shelf Implications for the scavenging of particle-reactive species. Cont Shelf Res 6 87-106... 

For convenience, these qualitative and quantitative absorption models have been classified into three categories based on their dependence on spatial and temporal variables [2], The first category is referred to as quasi-equilibrium models. The quasi-equilibrium model, including the pH-partition hypothesis... 

Figure 1 Overview of transport models for predicting oral drug absorption. Absorption models are classified into three categories based on their dependence on the spatial and temporal variables. These three categories are quasi-equilibrium, steady-state, and dynamic models. 

Sass RL, Andrews JA, Ding A, Fisher FM. Spatial and temporal variability in methane emissions from rice paddies Implications for assessing regional methane budgets. Nutr. Cycl. Agroecosys. 2002 64 3-7. 

Boyle EA. 1990. Temporal variability of lead in the western North Atlantic. Washington, DC National Science Foundation, Division of Ocean Sciences. 

Additionally, the integration of geographic information system (GIS) with analytical data is an effective procedure in addressing the problem of spatial and temporal variability of the different parameters involved in the environmental fate of chemicals. Based on accurate local estimations, GIS-based models would then also allow deriving realistic and representative spatially averaged regional PECs. Table 4 shows some studies that have used GIS-based methodologies to perform a site-specific risk assessment of PECs in different exposed ecosystems. 

Because of the irregular rainfall distribution, mean precipitation values have little meaning in the (semi)-arid zone, if not also the range of variation is indicated. This variability refers to both temporal and spatial variability. Temporal variability affects not only the onset and duration of the rains in the year, but plays also a role in year-by-year differences. The variability is highest in the hyper-arid zone, where the mean precipitation value is composed of a few intensive rainstorms. When these fall on a heated barren surface - as is often the case in the arid zone - a part of it is immediately evaporated and lost for soil processes. High rainfall intensity results on the other hand in a rapid saturation of the surface layers and creates lateral runoff and erosion, in particular on sloping land. Many arid and semi-arid soils show therefore features of gully and sheet erosion. 

Table 1 gives the values of design and operating parameters of a scale model fluidized with air at ambient conditions which simulates the dynamics of an atmospheric fluidized bed combustor operating at 850°C. Fortunately, the linear dimensions of the model are much smaller, roughly one quarter those of the combustor. The particle density in the model must be much higher than the particle density in the combustor to maintain a constant value of the gas-to-solid density ratio. Note that the superficial velocity of the model differs from that of the combustor along with the spatial and temporal variables. 

Webb BW, Walling DE (1993) Temporal variability in the impact of river regulation on thermal regime and some biological implications. Freshw Biol 29 167-182... 

Prats J, Val R, Armengol J, Dolz J (2010) Temporal variability in the thermal regime of the lower Ebro River (Spain) and alteration due to anthropogenic factors. Journal of Hydrology 387 105-118... 

Sanders, J.G., G.F. Riedel, and G.R. Abbe. 1991. Factors controlling the spatial and temporal variability of trace metal concentrations in Crassostrea virginica (Gmelin). Pages 335-339 in M. Elliott and J.P. Ducrotoy (eds.). Estuaries and Coasts Spatial and Temporal Comparisons. ECSA Sympos. 19 (Univ. Caen, France, 1989). Olsen Olsen, Fredensborg, Denmark. 

Enzyme activity (urease, amidase, dehydrogenase, pl-glucosidase, phosphatase, arylsulfatase, fluorescein diacetate hydrolysis) Laboratory incubation Indicates potential microbial activity and nutrient cycling reactions determined in nonstandard laboratory with specialized equipment highly spatially and temporally variable dependent upon organic inputs Dick et al. (1996) Parham et aL (2002)... 

Denitrification, a dissimilatory pathway of nitrate reduction (see Section 3.3 also) into nitrogen oxides, N2O, and dinitrogen, N2, is performed by a wide variety of microorganisms in the forest ecosystems. Measurable rates of N20 production have been observed in many forest soils. The values from 2.1 to 4.0 kg/ha/yr are typical for forest soils in various places of Boreal and Sub-Boreal Forest ecosystems. All in situ studies (field monitoring) of denitrification in forest soils have shown large spatial and temporal variability in response to varying soils characteristics such as acidity, temperature, moisture, oxygen, ambient nitrate and available carbon. 

HPLC has been further employed for the mesurement of the spatial and temporal variabilities of phytoplankton community structure [287], for the investigation of the seasonal change of algal pigments [288], for the study of the seasonal and interannual change of phytoplankton communities [289] and for the assessment of the tidal and diurnal periodicities of pigment profiles [290],... 

Y. Obayashi, E. Tanoue, K. Suzuki, N. Handa, Y. Nojiri and C.S. Wong, Spatial and temporal variabilities of phytoplankton community structure in the Northern North Pacific as determined by phytoplankton pigments. Deep Sea Res. Part I Oceanogr. Res. Papers 48 (2001) 439 169. 

In order to implement frequency domain based sensing systems capable of monitoring the temporal luminescence of sensors, in few seconds, data must be collected at multiple frequencies simultaneously. Single-frequency techniques have been used to make frequency domain measurements of luminescent decays. 14, 23 28) This approach is unsuitable for real-time applications since data must be acquired at several frequencies in order to precisely and accurately determine the temporal variables of luminescent systems. 1 Each frequency requires a separate measurement, which makes the single frequency approach too slow to monitor the evolution... 

Box models are limited in their ability to show temporal and spatial variability. In the case of the former, rates and reservoir sizes are liable to change over time. For example, plankton distributions tend to fluctuate on a seasonal, and even a daily, basis. Climate change appears to be causing rate and abundance changes over longer time periods, such as decades. This temporal variability is difficxflt to show in the box model format. One approach is to provide a range of values for the rate or reservoir size. Likewise,... 

In reality, the Oj saturation level of surface seawater is geographically and temporally variable, ranging from 60 to 110% with a mean ralue of 103% (Figure 6.2). 

This assvunes that the newly formed deep waters were at 100% saturation with respect to O2 when they were last at the sea surface. As noted in Chapter 6, the percent saturation of surfece water is geographically and temporally variable with an average value of 103%.) ... 

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