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Altimetric data from the TOPEX/POSEIDON mission will be used for studies of global ocean circulation and marine geophysics. However, it is first necessary to remove the ocean tides, which are aliased in the raw data. The tides are constrained by two distinct types of information: the hydrodynamic equations which the tidal fields of elevations and velocities must satisfy, and direct observational data from tide gauges and satellite altimetry. Here we develop and apply a generalized inverse method, which allows us to combine rationally all of this information into global tidal fields best fitting both the data and the dynamics, in a least squares sense. The resulting inverse solution is a sum of the direct solution to the astronomically forced Laplace tidal equations and a linear combination of the representers for the data functionals. The representer functions (one for each datum) are determined by the dynamical equations, and by our prior estimates of the statistics of errors in these equations. Our major task is a direct numerical calculation of these representers. This task is computationally intensive, but well suited to massively parallel processing. By calculating the representers we reduce the full (infinite dimensional) problem to a relatively low‐dimensional problem at the outset, allowing full control over the conditioning and hence the stability of the inverse solution. With the representers calculated we can easily update our model as additional TOPEX/POSEIDON data become available. As an initial illustration we invert harmonic constants from a set of 80 open‐ocean tide gauges. We then present a practical scheme for direct inversion of TOPEX/POSEIDON crossover data. We apply this method to 38 cycles of geophysical data records (GDR) data, computing preliminary global estimates of the four principal tidal constituents, M2, S2, K1, and O1. The inverse solution yields tidal fields which are simultaneously smoother, and in better agreement with altimetric and ground truth data, than previously proposed tidal models. Relative to the “default” tidal corrections provided with the TOPEX/POSEIDON GDR, the inverse solution reduces crossover difference variances significantly (≈20–30%), even though only a small number of free parameters (≈1000) are actually fit to the crossover data.

Linkages in the Landscape IUCN'S FOREST CONSERVATION PROGRAMMEIUCN's Forest Conservation Programme coordinates and supports the activities of the IUCN Secretariat and members working with forest ecosystems. The goal of forest conservation is achieved through promoting protection, restoration and sustainable use of forest resources, so that forests provide the full potential range of goods and services.The programme makes contributions to policy at various levels and uses field projects to derive lessons to feed into the policy debate. The principles of Caring for the Earth, published jointly by IUCN, WWF and UNEP in 1991, are applied to these projects, which combine the needs of conservation and those of local communities. One major activity is to develop coherent and informed policies on forest conservation in order to advocate the translation of policies into effective actions. IUCN frequently advises major development institutions on forest issues, to ensure that conservation priorities are adequately addressed in their projects and programmes. The Forest Conservation Programme receives generous financial support from the Government of the Netherlands. The IUCN Forest Conservation Programme Linkages in the Landscape The Role of Corridors and Connectivity in Wildlife Conservation Andrew F. BennettSchool of Ecology and Environment Deakin University -Melbourne Campus, Burwood, Victoria 3125, Australia IUCN -The World Conservation Union 2003The designation of geographical entities in this book, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of IUCN or Environment Australia concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The views expressed in this publication do not necessarily reflect those of IUCN or Environment Australia. This publication has been made possible in part by funding from Environment Australia. Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged.Reproduction of this publication for resale or other commercial purposes is prohibited without prior written permission of the copyright holder.Citation: Bennett, A.F. (1998Bennett, A.F. ( , 2003 When this volume was produced four years ago the title was prescient indeed -as the Vth World Parks Congress has selected more or less the same title for its first workshop stream ("more or less" because the workshop title is "Linkages in the landscape/seascape)". In fact, we are better thinking of the term "earthscape", which can be defined as a group of interconnected ecological systems. Earthscape also avoids the linguistic complications of trying to translate landscape into the common parlance of European, let alone global languages.The Secretariat of the linkages stream for the Vth World Parks Congress, together with the IUCN Commission on Ecosystem Management,...

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