Low-frequency variability in geopotential height records of the Northern Hemisphere is a topic of significance in atmospheric science, having profound implications for climate modeling and prediction. A debate has existed in the atmospheric science literature as to whether or not “regimes” or clusters exist in geopotential heights, and if so, how many such clusters. This paper tells the “detect...

Successful satellite operations often depend on the ability to precisely determine the satellite’s position throughout it’s operational lifetime. Often, simplified models are used to reduce the computational complexity when producing an orbit determination solution. One example is the use of lower order gravitational terms when computing the state transition matrix. The US Naval Research Labora...

In this paper we try to suggest a possible novel method to determine some selected even zonal harmonics Jl of the Earth’s geopotential. Time series many years long of suitably linearly combined residuals of some Keplerian orbital elements of certain existing geodetic SLR satellites would be examined. A CHAMP/GRACE-only background reference model should be used for the part of the geopotential w...

Two approaches to determining the Earth’s external potential field by using GPS technique are proposed. The first one is that the relation between the geopotential difference and the light signal’s frequency shift, between two separated points, is applied. The second one is that the spherical harmonic expansion series and a new technique dealing with the “downward continuation” problem are appl...

FFT and complex algebra-based methods of spherical harmonic analysis and synthesis are presented. Two computer programs in FORTRAN are developed based on the methods. Both general and special cases are discussed. Special cases involve the analyses of gravity changes of the hydrological origin and the atmospheric origin. Functionals of the Earth’s gravity field such as gravity anomaly and geoida...

Discrete Spherical Harmonic Transforms (SHTs) are commonly defined for equiangular grids on the sphere. However, when global array data exhibit near equidistributed patterns rather than equiangular grids, discrete SHTs require appropriate adaptations for analysis and synthesis. Computational efficiency and reliability impose structural constraints on possible equidistribution characteristics of...