Skip to Main content Skip to Navigation
Journal articles

Least-squares gradient calculation from multi-point observations of scalar and vector fields: methodology and applications with Cluster in the plasmasphere

Abstract : This paper describes a general-purpose algorithm for computing the gradients in space and time of a scalar field, a vector field, or a divergence-free vector field, from in situ measurements by one or more spacecraft. The algorithm provides total error estimates on the computed gradient, including the effects of measurement errors, the errors due to a lack of spatio-temporal homogeneity, and errors due to small-scale fluctuations. It also has the ability to diagnose the conditioning of the problem. Optimal use is made of the data, in terms of exploiting the maximum amount of information relative to the uncertainty on the data, by solving the problem in a weighted least-squares sense. The method is illustrated using Cluster magnetic field and electron density data to compute various gradients during a traversal of the inner magnetosphere. In particular, Cluster is shown to cross azimuthal density structure, and the existence of field-aligned currents in the plasmasphere is demonstrated.
Complete list of metadatas

Cited literature [24 references]  Display  Hide  Download

https://hal-insu.archives-ouvertes.fr/insu-02872307
Contributor : Nathalie Pothier <>
Submitted on : Wednesday, June 17, 2020 - 4:55:19 PM
Last modification on : Monday, September 21, 2020 - 11:34:08 AM

File

angeo-25-971-2007.pdf
Publisher files allowed on an open archive

Licence


Distributed under a Creative Commons Attribution - NonCommercial 4.0 International License

Identifiers

Collections

Citation

J. de Keyser, Fabien Darrouzet, M.W. Dunlop, Pierrette Décréau. Least-squares gradient calculation from multi-point observations of scalar and vector fields: methodology and applications with Cluster in the plasmasphere. Annales Geophysicae, European Geosciences Union, 2007, 25 (4), pp.971-987. ⟨10.5194/angeo-25-971-2007⟩. ⟨insu-02872307⟩

Share

Metrics

Record views

28

Files downloads

33