A Numerical Study of the Local Downslope Wind &amp;ldquo;Yamaji-kaze&amp;rdquo; in Japan

Saitō, Kazuo

doi:10.2151/jmsj1965.72.2_301

Cited by 37 publications

(3 citation statements)

References 35 publications

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“…This strongly stratified layer was not found in the soundings at Tateno. A flow over the mountain causes a lee side downslope wind, in a certain range of the stability and the flow regime (Saito 1994). The descending motion locally leads to adiabatic heating.…”

Section: Daytime Evolution Of the Local Frontmentioning

confidence: 99%

Vertical Structure of Local Fronts Observed in Kanto, Japan

Seino¹,

Yoshikado

Kobayashi

et al. 2003

Journal of the Meteorological Society of Japan

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This paper focuses on two cases of a local front that formed ahead of a synoptic cold front under a southwesterly inflow in the Kanto region.Vertical sounding data provided by an observation network of the Tsukuba Area Precipitation Studies (TAPS) enabled a detailed investigation of the mesoscale structure in the vicinity of the local front from its formation through dissipation. Despite some differences in synoptic features, the local front exhibited essential similarities in vertical structure between the two cases, as well as in horizontal structure. The local front, with WSW-ENE orientation, was well defined even in the daytime. A stable layer with a thickness of about 400 m formed on the cold side of the developed local front. As in the upper layer of warm inflow, southwesterly winds prevailed in this stable layer, except for the lowest 50-200 m. The maintenance mechanism of the local front is discussed. The evolution of the local front largely depends on the development of the stable layer on its cold side. In both cases, frontal formation began in the nighttime. A nocturnal cooling on the land surface contributed to forming a cold air mass on the northern side of the local front. In addition, the southwesterly inflow caused warming just above the surface-based cooling layer, which intensified the stratification. Furthermore, the observed vertical structure suggests that the locally modified circulation affected the frontal evolution. Two orographic effects on the circulation, 1) intensification of the inflow over the eastern part, and 2) downslope wind over the western part, both related to the mountains in the west of the Kanto region are expected. Especially, the downslope wind can reasonably explain the daytime persistence of the local front through the enhancement of stratification by adiabatic warming, and resultant influences on the mass transport.

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Section: Daytime Evolution Of the Local Frontmentioning

confidence: 99%

Vertical Structure of Local Fronts Observed in Kanto, Japan

Seino¹,

Yoshikado

Kobayashi

et al. 2003

Journal of the Meteorological Society of Japan

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“…To estimate directional variations, key phenomena are local topographic winds (e.g. downslope windstorms, DWs; gap winds, GWs), which have proven damaging to infrastructures (Arakawa, 1968;Saito, 1994). They generally originate from consistent directions determined by the terrain shape and are closely related to pressure patterns.…”

Section: Introductionmentioning

confidence: 99%

Assessment of extreme local topographic winds and their future changes from a massive high-resolution ensemble climate dataset

Kitano,

Ohba,

Soda

et al. 2023

Hydrological Research Letters

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The estimation of extreme wind speeds, their directional variation, and potential future changes is essential for windresistant design and is possible using climate models. Accurate evaluations of local topographic winds such as downslope windstorms and gap winds require highresolution calculation and many ensemble years. However, few climate databases satisfy both requirements and none have been validated for extreme wind speeds.We assessed directional extreme wind speeds using a massive high-resolution ensemble climate dataset (d4PDF-5km-DS) for Hokkaido Island, Japan. Despite some issues due to limited reproducibility of spring extratropical cyclones, downslope windstorms caused by large mountains are reproduced well, indicating decreasing wind speed under predicted future climate. The findings suggest future climatic conditions may influence extreme topographic wind speeds.

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“…The south foehn blows across the Sea of Japan side of Honshu (main island of Japan) (Arakawa et al, 1982;, Hokkaido (Mori and Sato, 2014), and Shikoku (Saito and Ikawa, 1993;Saito, 1994). The south foehn on the Hokuriku region in Honshu is the representative foehn in Japan.…”

Section: Introductionmentioning

confidence: 99%

Japan's south foehn on the Toyama Plain: Dynamical or thermodynamical mechanisms?

Kusaka

Nishi

Kakinuma

et al. 2021

Intl Journal of Climatology

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Japanese society has recently taken a greater interest in foehn warming because it has caused record-breaking high temperatures and sudden damage to rice crops. This is the first comprehensive climatological study focused on Japan's south foehn, which blows across the Toyama Plain in the Hokuriku region. Climatological analyses, including an objective selforganizing map and subjective analysis of 198 south foehn cases, revealed that $68.2% of the foehns occurred while an extratropical cyclone was passing through the Sea of Japan. Approximately 19.7% of the remaining foehns blew while an anticyclone covered Japan. Only 5.1% of all foehns occurred during a typhoon, but very high temperatures occurred when typhoons were approaching. Foehns were observed in all seasons but tended to blow more often in spring, when there are many migratory anticyclones and cyclones.Most of the foehns begin at night and end or pause during the day. This is due to the removal of the nocturnal stable layer and the development of a local daytime pressure gradient on the lee side. The dynamical mechanism provides the primary explanation for Japan's south foehn. Surprisingly, the foehns with precipitation on windward mountains slopes accounted for only $19.2% of all cases, with $40.0% being typhoon cases. Most of these are likely of multiple type; a pure thermodynamical type of foehn is a rare occurrence. Numerical simulations and back trajectory analyses for 76 selected foehn cases revealed that the majority of the air parcels originated from the south and passed straight over the Hida Highlands, between two mountain ranges, as a hybrid type of gap and foehn winds.

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A Numerical Study of the Local Downslope Wind “Yamaji-kaze” in Japan

Cited by 37 publications

References 35 publications

Vertical Structure of Local Fronts Observed in Kanto, Japan

Vertical Structure of Local Fronts Observed in Kanto, Japan

Assessment of extreme local topographic winds and their future changes from a massive high-resolution ensemble climate dataset

Japan's south foehn on the Toyama Plain: Dynamical or thermodynamical mechanisms?

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