An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model
Abstract. Within the framework of sea-level rise projections, there is a strong need for hindcast validation of the evolution of polar ice sheets in a way that tightly matches observational records (from radar and altimetry observations mainly). However, the computational requirements for making hin...
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ftcdlib:oai:escholarship.org/ark:/13030/qt4t58d0nn 2023-05-15T13:35:40+02:00 An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model Larour, Eric Utke, Jean Bovin, Anton Morlighem, Mathieu Perez, Gilberto 2016-05-09 application/pdf https://escholarship.org/uc/item/4t58d0nn unknown eScholarship, University of California qt4t58d0nn https://escholarship.org/uc/item/4t58d0nn CC-BY CC-BY article 2016 ftcdlib 2021-07-05T17:07:34Z Abstract. Within the framework of sea-level rise projections, there is a strong need for hindcast validation of the evolution of polar ice sheets in a way that tightly matches observational records (from radar and altimetry observations mainly). However, the computational requirements for making hindcast reconstructions possible are severe and rely mainly on the evaluation of the adjoint state of transient ice-flow models. Here, we look at the computation of adjoints in the context of the NASA/JPL/UCI Ice Sheet System Model, written in C++ and designed for parallel execution with MPI. We present the adaptations required in the way the software is designed and written but also generic adaptations in the tools facilitating the adjoint computations. We concentrate on the use of operator overloading coupled with the AdjoinableMPI library to achieve the adjoint computation of ISSM. We present a comprehensive approach to 1) carry out type changing through ISSM, hence facilitating operator overloading, 2) bind to external solvers such as MUMPS and GSL-LU and 3) handle MPI-based parallelism to scale the capability. We demonstrate the success of the approach by computing sensitivities of hindcast metrics such as the misfit to observed records of surface altimetry on the North-East Greenland Ice Stream, or the misfit to observed records of surface velocities on Upernavik Glacier, Central West Greenland. We also provide metrics for the scalability of the approach, and the expected performance. This approach has the potential of enabling a new generation of hindcast-validated projections that make full use of the wealth of datasets currently being collected, or already collected in Greenland and Antarctica, such as surface altimetry, surface velocities, and/or gravity measurements. Article in Journal/Newspaper Antarc* Antarctica East Greenland glacier Greenland Ice Sheet Upernavik University of California: eScholarship Greenland |
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Open Polar |
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University of California: eScholarship |
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description |
Abstract. Within the framework of sea-level rise projections, there is a strong need for hindcast validation of the evolution of polar ice sheets in a way that tightly matches observational records (from radar and altimetry observations mainly). However, the computational requirements for making hindcast reconstructions possible are severe and rely mainly on the evaluation of the adjoint state of transient ice-flow models. Here, we look at the computation of adjoints in the context of the NASA/JPL/UCI Ice Sheet System Model, written in C++ and designed for parallel execution with MPI. We present the adaptations required in the way the software is designed and written but also generic adaptations in the tools facilitating the adjoint computations. We concentrate on the use of operator overloading coupled with the AdjoinableMPI library to achieve the adjoint computation of ISSM. We present a comprehensive approach to 1) carry out type changing through ISSM, hence facilitating operator overloading, 2) bind to external solvers such as MUMPS and GSL-LU and 3) handle MPI-based parallelism to scale the capability. We demonstrate the success of the approach by computing sensitivities of hindcast metrics such as the misfit to observed records of surface altimetry on the North-East Greenland Ice Stream, or the misfit to observed records of surface velocities on Upernavik Glacier, Central West Greenland. We also provide metrics for the scalability of the approach, and the expected performance. This approach has the potential of enabling a new generation of hindcast-validated projections that make full use of the wealth of datasets currently being collected, or already collected in Greenland and Antarctica, such as surface altimetry, surface velocities, and/or gravity measurements. |
format |
Article in Journal/Newspaper |
author |
Larour, Eric Utke, Jean Bovin, Anton Morlighem, Mathieu Perez, Gilberto |
spellingShingle |
Larour, Eric Utke, Jean Bovin, Anton Morlighem, Mathieu Perez, Gilberto An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model |
author_facet |
Larour, Eric Utke, Jean Bovin, Anton Morlighem, Mathieu Perez, Gilberto |
author_sort |
Larour, Eric |
title |
An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model |
title_short |
An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model |
title_full |
An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model |
title_fullStr |
An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model |
title_full_unstemmed |
An Approach to Computing Discrete Adjoints for MPI-Parallelized Models Applied to the Ice Sheet System Model |
title_sort |
approach to computing discrete adjoints for mpi-parallelized models applied to the ice sheet system model |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
https://escholarship.org/uc/item/4t58d0nn |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Antarc* Antarctica East Greenland glacier Greenland Ice Sheet Upernavik |
genre_facet |
Antarc* Antarctica East Greenland glacier Greenland Ice Sheet Upernavik |
op_relation |
qt4t58d0nn https://escholarship.org/uc/item/4t58d0nn |
op_rights |
CC-BY |
op_rightsnorm |
CC-BY |
_version_ |
1766068662391799808 |