A fast multipole transformation for global climate calculations

Technical Report · Mon Jan 01 04:00:00 EST 1996

DOI:https://doi.org/10.2172/212488· OSTI ID:212488

Holmes, J A; Wang, Z; Drake, J B; Lyon, B F; Chen, W T

A fast multipole transformation is adapted to the evaluation of summations that occur in global climate calculations when transforming between spatial and spherical harmonic representations. For each summation, the timing of the fast multipole transformation scales linearly with the number of latitude gridpoints, but the timing for direct evaluations scales quadratically. In spite of a larger computational overhead, this scaling advantage renders the fast multipole method faster than direct evaluation for transformations involving greater than approximately 300 to 500 gridpoints. Convergence of the fast multipole transformation is accurate to machine precision. As the resolution in global climate calculations continues to increase, an increasingly large fraction of the computational work involves the transformation between spatial and spherical harmonic representations. The fast multipole transformation offers a significant reduction in computational time for these high-resolution cases.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 212488
• Report Number(s): ORNL/TM--13135; ON: DE96008764
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CALCULATION METHODS
CLIMATE MODELS
CLIMATES
CLIMATIC CHANGE
DATA
FORECASTING
GLOBAL ASPECTS