Large-scale structure formation and effective energy transfer in forced two-dimensional turbulence on a rotating spherer

JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EACA46

Subject Category: JSS Inter-University Research

Responsible Representative: Kiori Obuse, Professor, Okayama University
Contact Information: Kiori Obuse(obuse@okayama-u.ac.jp)
Members: Kiori Obuse, Yuki Yamaguchi

Abstract

One of the simplest mathematical models describing the dynamics of planetary atmospheres, the 2D barotropic turbulence on a rotating sphere, shows the spontaneous formation of large-scale zonal flows such as those seen in giant gas planets. However, this mechanism has not been fully clarified. The aim of this study is to elucidate the effective energy transfer that occurs during the formation of large-scale zonal flows, thereby contributing to our understanding of the mechanisms underlying the formation of large-scale structures.

Reference URL

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Reasons and benefits of using JAXA Supercomputer System

Since the research group with which we might collaborate had an account on the JAXA supercomputing system, we considered it desirable to use this system for sharing data in case of collaboration. Also, as the research was a continuation of the previous year's research and most of the data required was located on the JAXA supercomputing system, we wished to continue using the system.

Achievements of the Year

Firstly, we generated time-series data for forced two-dimensional turbulence on a rotating spherier. Although we have performed similar calculations in the past, we carried out the calculations again as higher-precision data was required for our purpose. With the aim of realising the time evolution of a flow field that changes over time from the formation of multiple zonal-band structure, through the merging of zonal flows, to a structure consisting of a few large-scale zonal flows, we generated data by varying the spatial scale and strength of the forcing, whilst balancing computational accuracy and computational time. Subsequently, using the aforementioned flow field data, we calculated the effective energy transfer between two modes whilst zonal flow merging was occurring. As the effective energy transfer between two modes is not naturally determined from the governing equations of the flow, we used the definition presented by Obuse and Yamada (JPSJ, 2020). Although this calculation has approximately 80% been done, it was not possible to finish it entirely within this financial year, and the analysis of the data will be carried over to the next financial year.

Publications

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Usage of JSS

Computational Information

Process Parallelization Methods: N/A
Thread Parallelization Methods: N/A
Number of Processes: 1
Elapsed Time per Case: 24 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.02

Details

Please refer to System Configuration of JSS3 for the system configuration and major specifications of JSS3.

Computational Resources
System Name	CPU Resources Used (Core x Hours)	Fraction of Usage*2(%)
TOKI-SORA	572651.31	0.03
TOKI-ST	0.00	0.00
TOKI-GP	0.00	0.00
TOKI-XM	0.00	0.00
TOKI-LM	0.00	0.00
TOKI-TST	0.00	0.00
TOKI-TGP	0.00	0.00
TOKI-TLM	0.00	0.00

File System Resources
File System Name	Storage Assigned (GiB)	Fraction of Usage*2(%)
/home	50.00	0.08
/data and /data2	10240.00	0.07
/ssd	0.00	0.00

Archiver Resources
Archiver Name	Storage Used (TiB)	Fraction of Usage*2(%)
J-SPACE	0.00	0.00

*1: Fraction of Usage in Total Resources: Weighted average of three resource types (Computing, File System, and Archiver).

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.

ISV Software Licenses Used

ISV Software Licenses Resources
	ISV Software Licenses Used (Hours)	Fraction of Usage*2(%)
ISV Software Licenses (Total)	0.00	0.00

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.