TY - JOUR
T1 - New representation of geomagnetic secular variation over restricted regions by means of spherical cap harmonic analysis
T2 - application to the case of Spain
AU - Torta, J. M.
AU - García, A.
AU - Curto, J. J.
AU - De Santis, A.
N1 - Funding Information:
The authors wish to thank Gerry Haines and Frank Lowes for attending to some questions and providing some appreciated suggestions. The paper was improved after the remarks made by D.J. Kerridge and an anonymous referee. This work is part of research project No. PB87-0390 supported by the D.G.I.C.Y.T., Ministerio de Educación y Ciencia, Spain.
PY - 1992/12/1
Y1 - 1992/12/1
N2 - A model of the secular variation (SV) of the geomagnetic field over Spain and adjacent regions, using a particular application of spherical cap harmonic analysis (SCHA), is given. SCHA was directly applied as presented in a previous paper; however, some drawbacks were detected, making evident the limitations of the technique for fields with low spatial harmonic content, as in the case for SV over relatively small regions. After trying some alternative approaches to the conventional procedure, it has been discovered that the solution lies in increasing the cap half-angle (but the data continue to be restricted within the original cap) to obtain more suitable harmonic contributions. It is shown that inspection of the spatial power spectra of the SV field on different spherical caps is useful in selecting the cap half-angle.
AB - A model of the secular variation (SV) of the geomagnetic field over Spain and adjacent regions, using a particular application of spherical cap harmonic analysis (SCHA), is given. SCHA was directly applied as presented in a previous paper; however, some drawbacks were detected, making evident the limitations of the technique for fields with low spatial harmonic content, as in the case for SV over relatively small regions. After trying some alternative approaches to the conventional procedure, it has been discovered that the solution lies in increasing the cap half-angle (but the data continue to be restricted within the original cap) to obtain more suitable harmonic contributions. It is shown that inspection of the spatial power spectra of the SV field on different spherical caps is useful in selecting the cap half-angle.
UR - http://www.scopus.com/inward/record.url?scp=0027065591&partnerID=8YFLogxK
U2 - 10.1016/0031-9201(92)90011-J
DO - 10.1016/0031-9201(92)90011-J
M3 - Article
AN - SCOPUS:0027065591
SN - 0031-9201
VL - 74
SP - 209
EP - 217
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 3-4
ER -