Title:
Global Point Mascon Models for Simple Accurate Parallel Geopotential Computation
Global Point Mascon Models for Simple Accurate Parallel Geopotential Computation
Author(s)
Russell, Ryan P.
Arora, Nitin
Arora, Nitin
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Abstract
High-fidelity geopotential calculation using spherical harmonics (SH) is expensive
and relies on recursive non-parallel relations. Here, a global point mascon
(PMC) model is proposed that is memory light, extremely simple to implement
(at any derivative level), and is naturally amenable to parallelism. The gravity
inversion problem is posed classically as a large and dense least squares estimation
problem. The well known ill-conditioned nature of the inversion is overcome
in part using orthogonal solution methods, a judicious choice for the mascon
distribution, and numerically preferred summation techniques. A variety of
resolutions are examined including PMC models with up to 30,720 mascons.
Measurements are simulated using truncated SH evaluations from the GGM02C
gravity field derived from the GRACE spacecraft. Resolutions are chosen in order
to target residual levels at least an order of magnitude smaller than the published
expected errors of the GGM02C. A single Central Processing Unit (CPU)
implementation is found to be approximately equal in speed compared to SH for
all resolutions while a parallel implementation on an inexpensive Graphics
Processing Unit (GPU) leads to order of magnitude (13 to 16 times) speedups in
the case of a 156x156 gravity field. A single CPU Matlab implementation is
competitive in speed with compiled code due to Matlab's efficient use of large
matrix operations.
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Date Issued
2011-02
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Text
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Paper
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