in-situ observation: 2
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Uncovering the relationships among air pollution (aerosols, PM2.5), wildfires, snow and ice, and climate change in the Arctic and cryosphere for a sustainable society in the future!
An atmospheric scientist working in the Arctic and cryosphere, tackling wildfires, air quality, snow and ice, and climate change
I am conducting a wide range of research on wildfires and their air quality (aerosols and PM2.5), including analysis and prediction of the factors that cause them and impact assessment (climate, health, economy, etc.), using various research methods from observation to data analysis and modeling.
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Figure 1b from Yasunari et al. (2018, Sci. Rep.). Daily mean PM2.5 concentration on July 25, 2014, calculated using NASA's MERRA-2 reanalysis data. The white circle indicates the location of Sapporo City.
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A commercial version of the PM2.5 measurement system for cold regions, updated from the prototype in Yasunari et al. (2022, J. Environ. Manage.). Anyone can purchase it from Tanaka Co., Ltd. (http://kktanaka.co.jp/products; the iron box and the low-cost PM2.5 sensor must be obtained separately)
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A climate (atmospheric circulation) pattern that can likely cause co-occurrences of European heatwaves and wildfires in Siberia and subarctic North America (Alaska and Canada), as discovered in Yasunari et al. (2021, Environ. Res. Lett.): the pattern was named the circum-Arctic wave (CAW) pattern because it is a pattern in which anticyclonic circulation is arranged to surround the Arctic. The figure is from Figure 9 of the paper (created by the current “Science Manga Studio Co., Ltd.”: https://www.sciencemanga.jp/).
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In Yasunari et al. (2024, Atmos. Sci. Lett.), the authors used the commercial PM2.5 measurement system for cold regions and, for the first time, performed the local ambient air quality observation (i.e., PM2.5 measurement) in Qaanaaq, northwest Greenland, in the summer of 2022. They also captured the worsened air quality during the local open waste burning (the figure is the Graphic Abstract of the paper).
Research
In recent years, we have been hearing more and more news about wildfires. Large-scale wildfires can transport air pollution (PM2.5) not only to the area where they occur but also to areas downwind, potentially affecting the people who live there. For this reason, it is necessary to identify the causes of wildfires and the atmospheric aerosols (air pollution) they produce and assess the diverse effects (such as climate, health, social and economic) that follow. In addition, it is extremely important to predict these effects based on the knowledge gained from the perspective of taking measures for people living in the downwind area from where the fires occur. To achieve the above objectives, we have developed a portable PM2.5 measurement system for cold regions, conducting multi-location observations of air quality such as PM2.5, analyzing large-scale global data (satellite, model, re-analysis data, etc.), and conducting research using various methods such as machine learning prediction (we are also conducting joint research with NASA and interdisciplinary research).
Teppei J. Yasunari Specially Appointed Associate ProfessorPh.D. in the field of Earth System Science -
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Simultaneous Observation of Electrical Properties and Structural Changes Using an Electron Microscope
The relationships between electrical properties and structural changes can be evaluated and validated
An electronic device fragment is placed in the electron microscope, and a movable probe electrode is applied to it, enabling observation by the electron microscope while evaluating its electrical characteristics. A MOSFET is connected to the sample side electrode to suppress excessive current. It allows evaluation of the correlation between electrical characteristics and structural changes and is useful to investigate the cause of failures.
Research
Our in-situ electron microscopy system is capable of three-terminal device measurements using two movable probes and a fixed sample holder as electrodes. A MOS transistor is inserted in the sample holder to limit the excess current flow due to stray capacitance.
Microelectronic devices that are almost ready for practical application include devices such as phase-change memory and resistance change memory that can predict structural changes accompanying resistance changes. It is difficult to confirm the mechanism of resistance changes in microdevices due to their high operating speed and nanoscale structure, but this system enables the evaluation of such a mechanism and helps to efficiently investigate the cause of the defective operation and ensure its reliability. By using this system, we can also effectively confirm the operating functions and evaluate the causes of defects in nanostructured functional devices, such as nanomachines and nanostructured secondary batteries, which are expected to be further developed in the future.
