The University of Tokyo · Earth and Planetary Sciences
Professor Hisashi Yashiro's research lab specializes in high-resolution atmospheric modeling, numerical weather prediction, and advanced data assimilation techniques for improving weather and climate simulations. The lab focuses on developing and optimizing global cloud-resolving models such as NICAM, integrating them with ensemble-based data assimilation systems to enhance forecast accuracy and reduce uncertainty. Their work emphasizes computational efficiency, leveraging exascale supercomputing architectures like the K computer and TSUBAME2.5 to achieve unprecedented model resolution and ensemble size. The lab also investigates atmospheric trace gases, such as H₂ and CO, to understand their global distributions and interactions with the terrestrial biosphere and climate system.
Figures are computed from collected data and may differ slightly.
Abstract. The global tropospheric distribution of molecular hydrogen (H2) and its uptake by the soil are simulated using a model called CHemical AGCM (atmospheric general circulation model) for the Study of the Environment and Radiative forcing (CHASER), which incorporates a two-layered soil diffusion/uptake process component. The simulated distribution of deposition velocity over land is influenced by regional climate, and has a global average of 3.3×10−2 cm s−1. In the region north of 30° N, t
Resolution dependence was found in the simulated diurnal precipitation cycle over land in the tropics. We conducted a series of grid refinement experiments of the atmosphere from 14 km to 0.87 km using a global high-resolution model without any convection parameterizations. In the high-resolution experiment, the peak of the cycle was earlier and precipitation at the peak was higher. The characteristics of the simulated diurnal precipitation cycle changed at a grid spacing of around 2-3 km. The p
Systematic observations of atmospheric carbon monoxide (CO) have been carried out in the western part of the Pacific Ocean since February 1990. The average CO concentration showed a latitudinal gradient, with higher values in the northern hemisphere than in the southern hemisphere. A clear seasonal CO cycle was found nearly at all sampling locations, showing maximum and minimum concentrations in spring and summer, respectively. In the 30°–35°N latitude zone, the average CO concentration was high
Numerical weather prediction (NWP) supports our daily lives. Weather models require higher spatiotemporal resolutions to prepare for extreme weather disasters and reduce the uncertainty of predictions. The accuracy of the initial state of the weather simulation is also critical; thus, we need more advanced data assimilation (DA) technology. By combining resolution and ensemble size, we have achieved the world’s largest weather DA experiment using a global cloud-resolving model and an ensemble Ka
Abstract. In this paper, we propose the design and implementation of an ensemble data assimilation (DA) framework for weather prediction at a high resolution and with a large ensemble size. We consider the deployment of this framework on the data throughput of file input/output (I/O) and multi-node communication. As an instance of the application of the proposed framework, a local ensemble transform Kalman filter (LETKF) was used with a Non-hydrostatic Icosahedral Atmospheric Model (NICAM) for t
We summarize the optimization and performance evaluation of the Nonhydrostatic ICosahedral Atmospheric Model (NICAM) on two different types of supercomputers: the K computer and TSUBAME2.5. First, we evaluated and improved several kernels extracted from the model code on the K computer. We did not significantly change the loop and data ordering for sufficient usage of the features of the K computer, such as the hardware-aided thread barrier mechanism and the relatively high bandwidth of the memo
Abstract. The molecular hydrogen (H2) in the troposphere is highly influenced by the strength of H2 uptake by the terrestrial soil surface. The global distribution of H2 and its uptake by the soil are simulated by using a model called CHemical AGCM for Study of Environment and Radiative forcing (CHASER), which incorporates a 2-layered soil diffusion/uptake process component. The simulated distribution of deposition velocity over land reflects regional climate and has a global average of 3.3 × 10
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