Patchy Distribution Fields: Sampling Distance Unit of a Spiral Survey and Reconstruction Adequacy |
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Authors: | I Kalikhman |
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Institution: | (1) Yigal Allon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research Ltd, Tel-Shikmona, P.O. Box 8030, Haifa, 31080, Israel |
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Abstract: | A mathematical model is used to examine the effects of choosing various units of sampling distance of a spiral acoustic survey
on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches (or gaps) of different
shapes and spatial orientations, and an acoustic survey by a spiral of Archimedes along which a unit of sampling distance
is set. For comparison, surveys are imitated by parallel transects along which the same unit of sampling distance is set.
Adequacy of the reconstructed fields to those originally generated is evaluated by calculating their correlations (r). In the case of a spiral survey, the mathematical experiments conducted show that an immovable field can be reconstructed
properly (r
2 > 0.70) if the ratio of the units of sampling distance to the autocorrelation radius for the field averaged in various directions
d/R
av < 1.0–1.5. Regarding immovable fields, the spiral surveys ensure, practically speaking, the same adequacy of the field reconstruction
as do surveys by parallel transects with the same unit of sampling distance. In regard to movable fields, a comparison of
the results of spiral surveys with those of surveys by parallel transects indicates that the former may ensure even higher
adequacy of the field reconstruction than do the latter, provided that the units of sampling distances in these surveys are
equal to each other. |
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Keywords: | Adequacy Anisotropy Design Mathematical simulation Patch Reconstruction Sampling distance unit Spiral |
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