3-D radiative transfer in large-eddy simulations – experiences coupling the TenStream solver to the UCLA-LES
The recently developed 3-D TenStream radiative transfer solver was integrated into the University of California, Los Angeles large-eddy simulation (UCLA-LES) cloud-resolving model. This work documents the overall performance of the TenStream solver as well as the technical challenges of migrating fr...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-04-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/9/1413/2016/gmd-9-1413-2016.pdf |
| Summary: | The recently developed 3-D TenStream radiative transfer solver
was integrated into the University of California, Los Angeles large-eddy simulation (UCLA-LES) cloud-resolving model. This work documents
the overall performance of the TenStream solver as well as the technical
challenges of migrating from 1-D schemes to 3-D schemes. In particular the
employed Monte Carlo spectral integration needed to be reexamined in
conjunction with 3-D radiative transfer. Despite the fact that the spectral
sampling has to be performed uniformly over the whole domain, we find that
the Monte Carlo spectral integration remains valid. To understand the
performance characteristics of the coupled TenStream solver, we conducted
weak as well as strong-scaling experiments. In this context, we investigate
two matrix preconditioner: geometric algebraic multigrid
preconditioning (GAMG) and block Jacobi incomplete LU (ILU) factorization
and find that algebraic multigrid preconditioning performs well for complex scenes and
highly parallelized simulations. The TenStream solver is tested for up to
4096 cores and shows a parallel scaling efficiency of
80–90 % on various supercomputers. Compared to the widely
employed 1-D delta-Eddington two-stream solver, the computational costs
for the radiative transfer solver alone increases by a factor of 5–10. |
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| ISSN: | 1991-959X 1991-9603 |