Error Analysis of Total Field Models Derived from POGS Data

Ultré-Guérard, Pascale; Achache, J.

doi:10.5636/jgg.49.453

Cited by 3 publications

(1 citation statement)

References 25 publications

(41 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These biases are thought to stay constant with time. This is confirmed in a recent paper in which observatory data corrected with biases calculated during the Magsat epoch are shown to be compatible with data from the POGS satellite for the period 1991-1993 (Ultré-Guérard and Achache, 1997).…”

Section: Inverse Problemsupporting

confidence: 79%

Improving geomagnetic field models for the period 1980–1999 using Ørsted data

et al. 2014

Self Cite

View full text Add to dashboard Cite

The Danish satellite Ørsted is due to be launched in 1998, and should provide, for the first time since the Magsat mission (1979-1980), a dense and global coverage of the Earth's surface with vector measurements of the magnetic field. In this paper, we compare the expected error in the main field models computed for the 1970-1999 time interval using observatory data, with or without the a priori information given by the knowledge of the field at both Magsat and Ørsted epochs. This work is based on the reasonable hypothesis that the main field models derived from Ørsted data will be as accurate as the Magsat models. The a priori information given by the Magsat and Ørsted models is based on a linear behaviour of the rate-of-change of the field throughout this period, plus a noise level which can be estimated as a function of time and degree from past field changes. The expected error in the models computed for the 1980-1999 period with a priori information appears to be significantly smaller than the expected error in the models computed without this information. This result is related to the heterogeneous distribution of the observatories over the Earth surface. Consequently, when the Ørsted data is available, improved models can be computed for the 1980-1999 period particularly in regions without observatory data. This method with a priori information may allow the use of the same set of observatories throughout the entire period. Indeed, our method alleviates the requirement of a very dense data distribution.

show abstract

Section: Inverse Problemsupporting

confidence: 79%

Improving geomagnetic field models for the period 1980–1999 using Ørsted data

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

Reducing the Backus Effect given some knowledge of the dip‐equator

Ultré-Guérard

Hamoudi

Hulot

1998

Geophysical Research Letters

View full text Add to dashboard Cite

Abstract.Geomagnetic field models computed from intensity measurements on or near the Earth's surface are plagued with strong errors known as the "Backus effect". These errors are related to the mathematical non-uniqueness of the solution which can be theoretically removed by the knowledge of the dip-equator location. Here, we present. a new method for computing models using intensity data and additional information about the location of the dip-equator. We first give a numerical validation of this approach in an ideal case in which the dip-equator can be assumed to be perfectly located. We then show that in practice, updating a good past model of the field with a model of secular variation can constrain the location of the dip-equator sufficiently for our method to be useful. Implications for the planning of future satellite missions are briefly discussed.

show abstract

Magnetic field modelling from scalar-only data: Resolving the Backus effect with the equatorial electrojet

2005

View full text Add to dashboard Cite

It is well known that models of the global geomagnetic field constructed from only measurements of the field intensity suffer from large errors arising from the Backus or perpendicular error effect. Knowledge of the location of the magnetic dip equator is in principal sufficient to eliminate this error. We investigate constraining the location of the dip equator using observations of the equatorial electrojet in intensity measurements made from the CHAMP satellite. While the models generated are inferior compared with models obtained from oriented three-component vector data, they may be of sufficient quality to allow construction of future global geomagnetic reference models in the absence of vector data.

show abstract

Error Analysis of Total Field Models Derived from POGS Data

Cited by 3 publications

References 25 publications

Improving geomagnetic field models for the period 1980–1999 using Ørsted data

Improving geomagnetic field models for the period 1980–1999 using Ørsted data

Reducing the Backus Effect given some knowledge of the dip‐equator

Magnetic field modelling from scalar-only data: Resolving the Backus effect with the equatorial electrojet

Contact Info

Product

Resources

About