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4. Spatial Statistics in Environmental Science
Pages 71-86

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From page 71... ... Also discussed briefly are some aspects of monitoring network design and the usefulness of point process models in developing global climate models. 4.2 Estimating Spatial Covariance The fundamental problem of environmetrics is that the observable processes of interest are highly variable. Read the entire page →
From page 72... ... Common to these methods is the necessity to determine the spatial covariance. The development of nonparametric procedures for interpolating observed spatial covariances of a random function sampled at a finite number of Tocations has lagged wed behind the development of interpolation methods for the expected value of the underlying function. Read the entire page →
From page 73... ... The resulting nonparametric models for spatial covariance are constrained to be positivedefinite or, in the terminology of geostatistics, the variogram models are conditionally non-negative-definite. This is obtained by fitting a mixture of covariance functions of Gaussian type in the MDS step of the algorithm. Read the entire page →
From page 74... ... 4.2.1 Example: Spatial Variation in Solar Radiation We present here a preliminary analysis of data collected from a solar radiation monitoring: network in southwestern British Columbia, Canada (Hay, ~ feasibility of solar power generation in British Columbia. This example manifests a somewhat extreme but easily understood form of nonstationarity in the spatial covariance structure of the solar radiation field. Read the entire page →
From page 75... ... These transformations removed the major aspect of seasonality associated with the orientation of the earth with respect to the sun. However, the spatial covariance structure retains seasonal structure because of variation in the atmospheric processes. Read the entire page →
From page 76... ... Switzer (1979) argues that for estimating are al averages, the search for a design that minimizes mean squared estimation error is unnecessary, since the criterion is relatively insensitive to design changes among sensible designs. Read the entire page →
From page 77... ... use a certain nonparametric testing procedure, a sulfate deposition mode! fitted to data from New York state, and simulated sulfate deposition experiments with step changes of various magnitudes, including 20~o. Read the entire page →
From page 78... ... suggest circumventing these difficulties by an approach that may be suboptimal in specific cases but has overall merits for these types of networks. We let Z denote a random field of measurable quantities indexed by potential site labels i. Read the entire page →
From page 79... ... of nine monitoring stations (Figure 4.4) in the northeastern United States was initiated in 1976 with the objective of creating a long-term, high-quality data base for the development of regional transport and deposition models. Read the entire page →
From page 80... ... On the other hand, the geographically extreme stations in Delaware, Virginia, and Tennessee are all poorly predicted, and are therefore highly informative stations. 4.4 Modeling Precipitation Using Space-Time Point Processes An environmental problem of enormous potential impact is the global warming due to increased CO2 concentration in the atmosphere. Read the entire page →
From page 81... ... These cores originate in generating cells aloft (in warm frontal bands) or within layers of potentially unstable air (in cold frontal bands) Read the entire page →
From page 82... ... Recent advances in satellite and radar imagery enables the identification of some of the major features of the model, and thus can both suggest functional forms for some of the parameter functions and permit testing the goodness of fit of the model. The problem of parameter identification from time-averaged quantities is discussed in Guttorp (1986) Read the entire page →
From page 83... ... [6] Guttorp, P., On binary time series obtained from continuous time point process models describing rainfall, Water Resour. Read the entire page →
From page 84... ... D Sampson, Nonparametric estimation of spatial covariance with an application to monitoring network design, to appear in Statistics in Environmental and Earth Sciences, P Read the entire page →
From page 85... ... D., and P Guttorp, Nonparametric Estimation of NonStationary Spatial Covariance Structure, Department of Statistics, University of Washington, SIMS Technical Report 148 (1990~. Read the entire page →
From page 86... ... Loader, Spatial covariances, talk at ISI satellite meeting on Statistics, Earth and Space Sciences (1989) , Leuven (to appear) Read the entire page →

From page 71...

... Also discussed briefly are some aspects of monitoring network design and the usefulness of point process models in developing global climate models. 4.2 Estimating Spatial Covariance The fundamental problem of environmetrics is that the observable processes of interest are highly variable.

4. Spatial Statistics in Environmental Science Pages 71-86

4. Spatial Statistics in Environmental Science
Pages 71-86