|Last modified date：2023.10.06
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Reseacher Profiling Tool Kyushu University Pure
Doctor of Philosophy (Mie Univesity)
Country of degree conferring institution (Overseas)
Field of Specialization
Meteorology and Climate Dynamics
ORCID(Open Researcher and Contributor ID)
Total Priod of education and research career in the foreign country
Academic ActivitiesMembership in Academic Society
|Yuta Ando, Koji Yamazaki, Yoshihiro Tachibana, Masayo Ogi, Jinro Ukita, Detection of a climatological short break in the polar night jet in early winter and its relation to cooling over Siberia, ATMOSPHERIC CHEMISTRY AND PHYSICS, 10.5194/acp-18-12639-2018, 18, 17, 12639-12661, 2018.08, [URL], The polar night jet (PNJ) is a strong stratospheric westerly circumpolar wind at around 65 degrees N in winter, and the strength of the climatological PNJ is widely recognized to increase from October through late December. Remarkably, the climatological PNJ temporarily stops increasing during late November. We examined this "short break" in terms of the atmospheric dynamical balance and the climatological seasonal march. We found that it results from an increase in the upward propagation of climatological planetary waves from the troposphere to the stratosphere in late November, which coincides with a maximum of the climatological Eliassen-Palm (EP) flux convergence in the lower stratosphere. The upward propagation of planetary waves at 100 hPa, which is strongest over Siberia, is related to the climatological strengthening of the tropospheric trough over Siberia. We suggest that longitudinally asymmetric forcing by land-sea heating contrasts caused by their different heat capacities can account for the strengthening of the trough..
|Yuta Ando, Masayo Ogi, Yoshihiro Tachibana, Abnormal Winter Weather in Japan during 2012 Controlled by Large-Scale Atmospheric and Small-Scale Oceanic Phenomena, MONTHLY WEATHER REVIEW, 10.1175/MWR-D-14-00032.1, 143, 1, 54-63, 2015.01, [URL], Negative Arctic Oscillation (AO) and western Pacific (WP) indices persisted from October to December 2012 in the Northern Hemisphere. For the first time, the monthly AO and WP were both negative for three consecutive months since records have been kept. Although in general negative AO and WP phases cause Siberia, East Asia, and Japan to be abnormally cold, Japan was relatively warm in October 2012 even though both the AO and WP were strongly negative. The temperature of the Sea of Japan reached a record-breaking high in October 2012, and it was found that heating by these very warm waters, despite the small size of the Sea of Japan, overwhelmed the cooling effect of the strongly negative AO and WP in October. Linear regression analyses showed that Japan tends to be warm in years when the Sea of Japan is warm. Consequently, the temperature over Japan is controlled by interannual variations of small-scale oceanic phenomena as well as by large-scale atmospheric patterns. Previous studies have ignored such small-scale oceanic influences on island temperatures..
- THE JAPANESE SOCIETY OF SNOW AND ICE
- THE OCEANOGRAPHIC SOCIETY OF JAPAN
- THE JAPAN SOCIETY OF FLUID MECHANICS
- METEOROLOGICAL SOCIETY OF JAPAN
- JAPAN GEOSCIENCE UNION
- The Oceanography Society
- European Geosciences Union
- American Meteorological Society
- American Geophysical Union