Marine heatwaves (MHWs), which are characterized by extremely warm water, can harm the marine ecosystem and fishing industry; improving the prediction of such events could reduce their harmful impact. In this study, we examined MHWs occurring in the North Pacific in winter/early spring, and their relationship with North Pacific subtropical mode water (STMW), based on the data analysis and numerical experiments. The time-lagged correlation between the cumulative intensity of MHWs and volume of STMW in March of each year suggests that STMW can modulate MHWs for up to three years after its formation. A patch of statistically significant negative correlation initially appeared in the formation region of the STMW but was found to the east of it near the Transition Zone Chlorophyll Front (TZCF) after one year. This patch stagnated near this remote site in the second winter and early spring. Passive tracer experiments using a numerical model indicate that the STMW, formed near the Kuroshio Extension in March, moves to the east underneath the mixed layer and is entrained to the surface in the following winter while altering the properties of STMW. The STMW reemerges in the second winter, after stagnating under the mixed layer near the TZCF. This suggests that the reemergence of STMW can suppress MHWs in the North Pacific during winter and early spring by reducing the sea surface temperature; if the volume of STMW is anomalously low, there is a greater likelihood of the occurrence of MHWs near the TZCF in the following two winters and early springs. Our results indicate that understanding STMW formation is crucial for predicting MHWs in the North Pacific Ocean during winter and early spring.
The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 resulted in the release of immense amounts of radioactive materials into the ocean. However, the dispersion of radioactive materials in the subsurface has not yet been clarified due to the spatiotemporal limitation of observations. Thus, herein, a tracer experiment was implemented using a three-dimensional numerical model to estimate the dispersion path of 137Cs released directly from the FDNPP and its travel time in the subsurface of the North Pacific Ocean from 2011 to 2020. The results show that the subsurface 137Cs spreads by two mode waters, namely, Sub-Tropical Mode Water (STMW) and Central Mode Water (CMW). Subsurface 137Cs primarily spreads clockwise in the sub-tropical region, while a portion driven by STMW is dispersed southward. The clockwise dispersion path of 137Cs released into the ocean by STMW is relatively shallower and inward than that by CMW. The 137Cs that was spread clockwise reached the east of Taiwan and the Philippines via STMW and CMW nine years after the accident, respectively. The model described in this study is applicable for estimating the water path and travel time of tritium water planned to be discharged from Fukushima.
Many commercial cloud computing companies provide technologies such as high-performance instances, enhanced networking and remote direct memory access to aid in High Performance Computing (HPC). These new features enable us to explore the feasibility of ocean modelling in commercial cloud computing. Many scientists 5 and engineers expect that cloud computing will become mainstream in the near future. Thus, evaluation of the exact performance and features of commercial cloud services for numerical modelling is appropriate. In this study, the performance of the Regional Ocean Modelling System (ROMS) and the High Performance Linpack (HPL) benchmarking software package was evaluated on Amazon Web Services (AWS) for various configurations.Through comparison of actual performance data and configuration settings obtained from AWS and laboratory 10 HPC, we conclude that cloud computing is a powerful Information Technology (IT) infrastructure for running and operating numerical ocean modelling with minimal effort. Thus, cloud computing can be a useful tool for ocean scientists that have no available computing resource.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.