RT Journal Article T1 Construction of the maximal solution of Backus' problem in geodesy and geomagnetism A1 Díaz Díaz, Jesús Ildefonso A1 Díaz Díaz, Gregorio A1 Otero Juez, Jesús AB The (simplified) Backus' Problem (BP) consists in finding a harmonic function u on the domain exterior to the three dimensional unit sphere S, such that u tends to zero at infinity and the norm of the gradient of u takes prescribed values g on S. Except for a change of sign, the solution is not unique in general. However, there is uniqueness of solutions in the class of functions with the additional property that the radial component of the gradient of u on S is nonpositive. This is the geodetically relevant case. If a solution u with this property exists, then u is the maximal solution of the problem (and -u the minimal one). In this paper we propose a method of successive approximations to get this particular solution of BP and prove the convergence for functions g close to a constant function. PB Springer SN 0039-3169 YR 2011 FD 2011-07 LK https://hdl.handle.net/20.500.14352/42412 UL https://hdl.handle.net/20.500.14352/42412 LA eng NO DGISPI (Spain) NO Research Groups MOMAT (Ref. 910480) NO Geodesia (Ref. 910505) NO Initial Training Network FIRST of the Seventh Framework Programme of the European Commission (Grant Agreement Number 238702 DS Docta Complutense RD 24 abr 2025