Algorithm studies on how to obtain a conditional nonlinear optimal perturbation (CNOP)

The conditional nonlinear optimal perturbation (CNOP), which is a nonlinear generalization of the linear singular vector (LSV), is applied in important problems of atmospheric and oceanic sciences, including ENSO predictability, targeted observations, and ensemble forecast. In this study, we investi...

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Bibliographic Details
Published in:Advances in atmospheric sciences Vol. 27; no. 6; pp. 1311 - 1321
Main Authors: Sun, Guodong, Mu, Mu, Zhang, Yale
Format: Journal Article
Language:English
Published: Heidelberg SP Science Press 01.11.2010
Springer Nature B.V
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ISSN:0256-1530, 1861-9533
Online Access:Get full text
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Summary:The conditional nonlinear optimal perturbation (CNOP), which is a nonlinear generalization of the linear singular vector (LSV), is applied in important problems of atmospheric and oceanic sciences, including ENSO predictability, targeted observations, and ensemble forecast. In this study, we investigate the computational cost of obtaining the CNOP by several methods. Differences and similarities, in terms of the computational error and cost in obtaining the CNOP, are compared among the sequential quadratic programming (SQP) algorithm, the limited memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm, and the spectral projected gradients (SPG2) algorithm. A theoretical grassland ecosystem model and the classical Lorenz model are used as examples. Numerical results demonstrate that the computational error is acceptable with all three algorithms. The computational cost to obtain the CNOP is reduced by using the SQP algorithm. The experimental results also reveal that the L-BFGS algorithm is the most effective algorithm among the three optimization algorithms for obtaining the CNOP. The numerical results suggest a new approach and algorithm for obtaining the CNOP for a large-scale optimization problem.
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ISSN:0256-1530
1861-9533
DOI:10.1007/s00376-010-9088-1