Effect of Large Cities on Wind Systems Over Kanto Plain When Heavy Rainfall Occurred in Tokyo

Inamura, Tomohiko; Izumi, Takeki; Matsuyama, Hiroshi

doi:10.2208/jsceja.65.915

Cited by 3 publications

(2 citation statements)

References 22 publications

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“…They also demonstrated that precipitation was increased by anthropogenic heat. Inamura et al (2009) found that the wind convergence around urban areas in Tokyo was enhanced by the urban effect.…”

Section: Introductionmentioning

confidence: 99%

Diagnostic Study of the Effects of a Large City on Heavy Rainfall as Revealed by an Ensemble Simulation: A Case Study of Central Tokyo, Japan

Inamura

Izumi

Matsuyama

2011

Journal of Applied Meteorology and Climatology

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This study was undertaken to investigate the effects of a large city on heavy rainfall in Tokyo, Japan, based on an ensemble simulation with a large number of members. An ensemble simulation (24 members) of eight brief heavy rainfall events that occurred from 1999 to 2007 was performed. The ensemble simulation was performed using five objective analysis datasets [Japanese 25-yr Reanalysis (JRA-25), Regional Analysis (RANAL), NCEP Final Operational Global Analysis (NCEP-FNL), NCEP-Department of Energy Global Reanalysis 2 (NCEP/DOE-R2), and Global Analysis (GANAL)]. Land-use distributions of two types were prepared for numerical simulations: actual land use and virtual land use, in which all urban land use was converted to vegetation. Each member was simulated using actual land use and virtual land use. The effects of the urban area were then assessed by comparing the results of these simulations. Results indicate no large differences in the wind systems of the Kanto plain (roughly 100 km 3 100 km), where Tokyo is located, even if cities were converted entirely to vegetation. The influence of cities on wind systems of this scale was negligible. However, changes of wind convergence were found leeward of the urban area, which increased the horizontal vapor flux there. The precipitation also increased there due to the urban effects, despite the decrease in vertical vapor flux from the land surface. It is concluded that urban effects for Tokyo alter the wind characteristics leeward of the urban area and develop wind convergence and rainfall there.

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Section: Introductionmentioning

confidence: 99%

Diagnostic Study of the Effects of a Large City on Heavy Rainfall as Revealed by an Ensemble Simulation: A Case Study of Central Tokyo, Japan

Inamura

Izumi

Matsuyama

2011

Journal of Applied Meteorology and Climatology

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“…Furthermore, Inamura et al (2009) showed in their numerical simulations that large cities located in the Kanto plain affect the convergence of surface winds when heavy rainfall occurred in Tokyo. According to Fujibe et al (2009), the afternoon precipitation in central Tokyo during summer has been increasing at a rate of 30% per century.…”

Section: Introductionmentioning

confidence: 99%

Relationship between the Upper-level Winds and the Horizontal Movement of Localized Heavy Rainfall in the Afternoon of Summer Days around Tokyo

Goto

Sato

2022

SOLA

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The horizontal movement vectors of the maximum rainfall area associated with local heavy rainfall around Tokyo in the afternoon of high-temperature summer days were analyzed using a numerical algorithm in order to investigate their relationship to the wind vectors in the free atmosphere. First, the movement vectors were objectively identified every 10 minutes from radar echo intensity data, and their time average from the onset to the termination of a heavy rainfall event was calculated. The results show that the 2 Upper-level Winds and Horizontal Movement of Localized Heavy Rainfall maximum areas of localized heavy rainfall around Tokyo most frequently move to the east-southeast and southeast. Moreover, the direction of movement is shifted to the right relative to the mean direction of the free atmospheric winds in most cases. It is also implied that water vapor supply from the south in the boundary layer plays a role in the rightward movement.

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Meteorological Characteristics of Local Heavy Rainfall in the Fukuoka Plain

Hisada

Sugihara²,

Matsunaga³

2015

J. Disaster Res.

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Heavy local rainfall has been increasingly observed in urban Fukuoka on fine summer afternoons in recent years. Such rainfall tends to occur suddenly on calm afternoons and is considered to be caused by local wind conditions influenced by local topography rather than by weather fronts or typhoons. This local rainfall is considered to be caused by a mechanism different from similar rainfalls occurring on fine Kanto plain afternoons. We set up 14 rain gauges in urban Fukuoka in this study to clarify and confirm actual local rainfall conditions there. Maximum local rain is about 64 km2lasting 10 to 30 minutes. The maximum 10-minute rainfall was 13.8 mm. The average surface air temperature on days with local rainfall differs 2°–3°C from that on fine days. Upper atmosphere humidity distribution differs greatly between fine days and those with heavy local rain. Accordingly, heavy local rain is more likely to occur if surface air temperature and humidity in upper atmosphere rise above a certain level. Some difference is seen between days of heavy local rainfall and fine day in terms of the K index (KI), a measure of atmospheric stability. We confirmed that the atmospheric state becomes more unstable on days with heavy local rainfall than on fine days. Heavy local rainfall often begins in either the eastern or western inland Fukuoka plain and moves toward the coast. That is, based on numerical simulation using the meteorological mesoscale weather research and forecasting (WRF) model, wind blowing opposite to the sea wind blows in the upper atmosphere, moving cumulonimbus clouds causing heavy local rainfall toward the coast. We also confirmed that heavy local rainfall tends to occur in eastern inland areas with wind from the west, but tends to occur in western areas with wind from the east. We therefore assumed that heavy local rainfall in urban Fukuoka was triggered by updrafts generated when wind struck the inland Fukuoka plain mountain system.

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Effect of Large Cities on Wind Systems Over Kanto Plain When Heavy Rainfall Occurred in Tokyo

Cited by 3 publications

References 22 publications

Diagnostic Study of the Effects of a Large City on Heavy Rainfall as Revealed by an Ensemble Simulation: A Case Study of Central Tokyo, Japan

Diagnostic Study of the Effects of a Large City on Heavy Rainfall as Revealed by an Ensemble Simulation: A Case Study of Central Tokyo, Japan

Relationship between the Upper-level Winds and the Horizontal Movement of Localized Heavy Rainfall in the Afternoon of Summer Days around Tokyo

Meteorological Characteristics of Local Heavy Rainfall in the Fukuoka Plain

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