Meso-&amp;beta;-scale Vortices Developing along the Japan-Sea Polar-Airmass Convergence Zone (JPCZ)Cloud Band : Numerical Simulation

Nagata, Masashi

doi:10.2151/jmsj1965.71.1_43

Cited by 57 publications

(29 citation statements)

References 26 publications

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“…Several observational and numerical studies (e.g., Matsumoto et al 1967;Ninomiya 1989;Ninomiya and Hoshino 1990;Nagata 1993;Ninomiya et al 1996Ninomiya et al , 2004Yoshizaki et al 2004) showed that mesoscale circulation systems were generated in the polar-air streams over the Japan Sea, under the influence of the synoptic-scale disturbances. Such phenomena are not studied in this report, because of the insufficient time and horizontal resolution of the observations.…”

Section: Discussionmentioning

confidence: 99%

“…Detailed studies about variations of the polar-air outbreak over the Japan Sea are also needed for the verification of simulations by regional models (e.g., Yamagishi 1980b;Nagata 1993;Yoshizaki et al 2004) and simulations by the atmospheric general circulation models (e.g., Ninomiya et al 2006) of the polar-air outbreak and the airmass transformation. This is the basic motivation of this article.…”

Section: Introductionmentioning

confidence: 99%

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Synoptic-Scale Variations in the Polar Air-Mass Transformed over the Japan Sea

Ninomiya

2007

Journal of the Meteorological Society of Japan

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The present report studies synoptic-scale variations of the polar air-mass transformed over the Japan Sea, during the ''East Japan Sea Observation'' in the winters of 1976 and 1977. Rawinsonde observation data at a research vessel are used, in addition to data at operational upper observation stations and the objective analysis data.The multi-layer structure of the transformed air-mass, including the unstable lowest layer and the mixed layer capped by the stable layer, is formed in the transformed airmass over the Japan Sea. The mixed layer, which includes the sub-cloud layer and the cloud layer, is characterized by nearly vertically-uniform equivalent potential temperature. The height of the mixed layer top is 1000-1500 m, on the average, over the Japan Sea. The height increases toward the south, and reaches 2000-2500 m over the coastal area of Japan.The height of the mixed layer top, and the apparent total heat source in the transformed air-mass, vary widely in association with the synoptic-scale changes of polar-air outbreak. The height of the mixed layer top tends to increase in association with the increase of the apparent total heat source in the mixed layer, and the decrease of the vertical stability in the lower-middle troposphere. The snowfall depth over the coastal area of Japan tends to increase in association with the increase of the apparent total heat source over the Japan Sea. The important synoptic conditions for the occurrence of the heavy snowfalls are the intense polar-air outbreak, and/or the passage of the cold vortex or the deep cold trough over the Japan Sea.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synoptic-Scale Variations in the Polar Air-Mass Transformed over the Japan Sea

Ninomiya

2007

Journal of the Meteorological Society of Japan

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“…In the actual atmosphere, the polar-air streams indicate complicated variations under the influence of the mountains in the Continent (Nagata 1993). Sometimes, the polar mesoscale cyclones generate over the Asian coastal areas (Ninomiya 1989).…”

Section: Discussionmentioning

confidence: 99%

“…The precipitation simulated in his experiment is @1/5 of the observed precipitation. Nagata (1993) intended to simulate the Japan Sea Polar-air Convergence Zone (JPCZ; the shear zone over the western Sea of Japan occasionally induced on the lee of the high mountains in the Continent) and mesoscale vortexes formed along the JPCZ in 24 January 1990, by using an one-way triple-nested (horizontal resolution; 6, 18 and 54 km) regional primitive model. The inner finest-mesh domain of the model is @(500 km) 2 , which covers the western part of the Sea of Japan.…”

Section: Comparison With the Regional Model Simulationmentioning

confidence: 99%

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Polar-Air Outbreak and Air-Mass Transformation over the East Coast of Asia as Simulated by an AGCM

Ninomiya

Nishimura

Suzuki

et al. 2006

Journal of the Meteorological Society of Japan

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The present report studies features of the polar-air outbreak and the associated air-mass transformation over the east coast of Asia simulated in an AGCM (T106L52: a primitive equation spectral model, which has 52 s-levels and triangular spectral truncation at wave-number 106) that used climatological SST in comparison with the features described in several observational studies.The large-scale circulations are properly reproduced for January Y07 (the 7th year after the spin up integration). A typical case of polar-air outbreak simulated in January is studied in detail. During the polar-air outbreak, cyclonic northwesterly polar-air streams over the Sea of Japan and the northwestern Pacific, and anticyclonic northeasterly polar-air streams over the East China Sea and the South China Sea are reasonably simulated. During the polar-air outbreak, the sensible and latent heat fluxes simulated over the Sea of Japan reach to @150 and @250 W m À2 , while those over the East China Sea reach to @75 and @250 W m À2 , respectively. These simulated fluxes agree with the fluxes evaluated in observational studies. The multi-layer structure of the transformed air-mass, including the unstable surface layer, the subcloud layer, and the cloud layer capped by the stable layer, simulated over the coastal areas of Asia is consistent with the observations for the cases of typical polar-air outbreak.However, the precipitation over the coastal areas of Japan simulated during the polar-air outbreak is significantly small as compared with the observation. This is due to the insufficient horizontal resolution of the T106L52 to simulate mesoscale circulation systems which induce snowfalls. In addition, the duration of the polar-air outbreak simulated in the AGCM is relatively short as compared with that in the real atmosphere, since the anticyclone over the continent tends to extend eastward in the model.

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Dynamical role of the Changbai Mountains and the Korean Peninsula in the wintertime quasi‐stationary convergence zone over the Sea of Japan

Shinoda

Kawamura

Kawano

et al. 2020

Intl Journal of Climatology

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This study focused on a quasi-stationary convergence zone over the Sea of Japan (Japan Sea polar airmass convergence zone, JPCZ) in early winter and examined how the Changbai Mountains and the Korean Peninsula play an influential role in the formation and maintenance of the JPCZ and associated precipitation amounts in the coastal regions of central and western Japan. We performed numerical simulations with and without modified topography of the Changbai Mountains and the Korean Peninsula using a regional atmospheric model. The results show that the presence of the mountains is largely responsible for the JPCZ formation and usually contributes to the reduction of precipitation in the coastal regions. If specific conditions are satisfied, however, it can trigger heavy precipitation. One condition is the rapid growth of mesoscale eddies off the Sea of Japan coast under strong low-level wind convergence. The precipitation band involved in the enhanced eddies slowly migrates southward and reaches the coastal regions, causing heavy snowfall. Another condition is the change in background monsoonal flows associated with synoptic-scale cyclone development due to the orographic effect. The resultant background flows may help sustain a significant amount of precipitation in the coastal regions. Under the prevailing JPCZ, the mountains play two contradictory roles in modulating precipitation amounts in the coastal regions. K E Y W O R D S convergence zone, heavy snowfall, mesoscale disturbances 1 | INTRODUCTION The Sea of Japan coastal region of mainland Japan receives extremely heavy snowfall when the East Asian winter monsoon dominates. It has long been known that such heavy snowfall events are often involved in a quasistationary convergence zone over the Sea of Japan. Asai (1988) named it the Japan Sea polar airmass convergence zone (JPCZ) and reviewed its association with mesoscale disturbances developing over the Sea of Japan. Using a primitive model, Nagata et al. (1986) and Nagata (1987, 1991) investigated the formation mechanism of the JPCZ and emphasized that three major factors are indispensable for JPCZ formation: the presence

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Meso-β-scale Vortices Developing along the Japan-Sea Polar-Airmass Convergence Zone (JPCZ)Cloud Band : Numerical Simulation

Cited by 57 publications

References 26 publications

Synoptic-Scale Variations in the Polar Air-Mass Transformed over the Japan Sea

Synoptic-Scale Variations in the Polar Air-Mass Transformed over the Japan Sea

Polar-Air Outbreak and Air-Mass Transformation over the East Coast of Asia as Simulated by an AGCM

Dynamical role of the Changbai Mountains and the Korean Peninsula in the wintertime quasi‐stationary convergence zone over the Sea of Japan

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