scholarly journals Statistical Characteristics and Composite Environmental Conditions of Explosive Cyclones over the Japan Sea and Kuroshio/Kuroshio Extension

Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 17
Author(s):  
Shuqin Zhang ◽  
Gang Fu ◽  
Yu Zhang ◽  
Jianjun Xu ◽  
Yufeng Xue ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Kuroshio Extension ◽  
Japan Sea ◽  
Early Spring ◽  
Statistical Characteristics ◽  
Synoptic Scale ◽  
Explosive Cyclones ◽  
The Japan Sea ◽  
Upper Level Jet ◽  
The Kuroshio

Statistical characteristics and composite synoptic-scale environmental conditions of explosive cyclones (ECs) over the Japan Sea and Kuroshio/Kuroshio Extension are examined and compared using ERA5 atmospheric reanalysis to give a better understanding of their differences. ECs over the Japan Sea frequently occur in late autumn and early winter and those over the Kuroshio/Kuroshio Extension mainly occur in winter and early spring. The maximum deepening rate, minimum central sea level pressure and explosive-developing lifetime of ECs over the Kuroshio/Kuroshio Extension are generally larger, lower and longer, respectively, than those over the Japan Sea. ECs over the Kuroshio/Kuroshio Extension formed over the East China Sea tend to develop more rapidly, and weak and moderate ECs generally begin to develop explosively over the sea to the east of the Japan Islands, while the strong and super ECs over the sea to the south of Japan Islands have longer explosive-developing tracks. Composite analysis shows that synoptic-scale environmental conditions favoring rapid EC development over these two regions are significantly different. ECs over the Japan Sea have stronger baroclinicity and cyclonic vorticity, but weaker water vapor convergence and upper-level jet stream than those over the Kuroshio/Kuroshio Extension. The key factor contributing to the baroclinicity is the cold air intrusion over the Japan Sea and the strong warm current heating over the Kuroshio/Kuroshio Extension. The potential vorticity shows anomalies in upper and low levels for both EC areas and extends further downwards over the Japan Sea.

scholarly journals Influential Role of Moisture Supply from the Kuroshio/Kuroshio Extension in the Rapid Development of an Extratropical Cyclone

2015 ◽  
Vol 143 (10) ◽  
pp. 4126-4144 ◽  
Author(s):  
Hidetaka Hirata ◽  
Ryuichi Kawamura ◽  
Masaya Kato ◽  
Taro Shinoda
Keyword(s):  
Diabatic Heating ◽  
Rapid Development ◽  
Kuroshio Extension ◽  
Lower Troposphere ◽  
Active Role ◽  
Conveyor Belt ◽  
Synoptic Scale ◽  
Warm Front ◽  
The Kuroshio

Abstract This study focused on an explosive cyclone migrating along the southern periphery of the Kuroshio/Kuroshio Extension in the middle of January 2013 and examined how those warm currents played an active role in the rapid development of the cyclone using a high-resolution coupled atmosphere–ocean regional model. The evolutions of surface fronts of the simulated cyclone resemble the Shapiro–Keyser model. At the time of the maximum deepening rate, strong mesoscale diabatic heating areas appear over the bent-back front and the warm front east of the cyclone center. Diabatic heating over the bent-back front and the eastern warm front is mainly induced by the condensation of moisture imported by the cold conveyor belt (CCB) and the warm conveyor belt (WCB), respectively. The dry air parcels transported by the CCB can receive large amounts of moisture from the warm currents, whereas the very humid air parcels transported by the WCB can hardly be modified by those currents. The well-organized nature of the CCB plays a key role not only in enhancing surface evaporation from the warm currents but also in importing the evaporated vapor into the bent-back front. The imported vapor converges at the bent-back front, leading to latent heat release. The latent heating facilitates the cyclone’s development through the production of positive potential vorticity in the lower troposphere. Its deepening can, in turn, reinforce the CCB. In the presence of a favorable synoptic-scale environment, such a positive feedback process can lead to the rapid intensification of a cyclone over warm currents.

scholarly journals Unusually high sea level at the south coast of Japan in September 2011 induced by the Kuroshio

2020 ◽  
Author(s):  
Norihisa Usui ◽  
Koji Ogawa ◽  
Kei Sakamoto ◽  
Hiroyuki Tsujino ◽  
Goro Yamanaka ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
Phase Speed ◽  
Japan Sea ◽  
South Coast ◽  
The South ◽  
Characteristic Analysis ◽  
The Japan Sea ◽  
The Kuroshio

Abstract Using a coastal assimilation model, generation mechanism of unusually high sea level (UHSL) at the south coast of Japan in September 2011 is investigated. Both model results and tide gauge observations indicate that sea level rise associated with the UHSL event occurred twice in the middle and end of September. The first one, which is localized around the eastern part of the Seto Inland Sea, is caused by a cyclonic circulation in the Kii Channel formed as a result of northward migration of the Kuroshio axis toward Cape Shionomisaki. The second sea level rise, which is the main contributor to this UHSL event, is observed in wide areas not only at the south coast of Japan, but also at the coast of the Japan Sea. It is brought about by a coastal trapped wave (CTW) induced as a result of a fluctuation of the Kuroshio path to the south of the Boso Peninsula. The CTW with positive SSH anomalies propagates westward along the south coast of Japan, and then goes into the coast of the Japan Sea. Sensitivity experiments and a modal characteristic analysis indicate that the CTW is mainly characterized by the first mode baroclinic Kelvin wave. The phase speed for the first mode is calculated at 2.96 m s$$^{-1}$$ - 1 , which compares well with that estimated by tide gauge observations.

On the length and time scales of the power supply to the ocean between the meso-scale and the synoptic-scale

2020 ◽  
Author(s):  
Achim Wirth
Keyword(s):  
Gulf Stream ◽  
Kuroshio Extension ◽  
Surface Wind ◽  
Coarse Graining ◽  
Power Input ◽  
Ocean Dynamics ◽  
Synoptic Scale ◽  
Surface Wind Stress ◽  
Using Data ◽  
The Kuroshio

<p> The input of mechanical power to the ocean due to the surface wind-stress, in regions which correspond to different regimes of ocean dynamics, is considered using data from satellites observations. Its dependence on the coarse-graining range of the atmospheric and oceanic velocity in space from 0.5° to 10° and time from 6h to 40 days is determined.  In the area of the Gulf Stream and the Kuroshio extensions the dependence of the power-input on space-time coarse-graining  varies over tenfold for the coarse-graining considered. It decreases over twofold for the Gulf Stream extension and threefold for the Kuroshio extension, when the coarse-graining length-scale passes from a few degrees to 0.5° at a temporal coarse-graining scale of a few days. It increases over threefold in the Gulf Stream and the Kuroshio extensions when the coarse-graining passes from several days to 6h at a spatial coarse graining of a few degrees. The power input is found to increase monotonically with shorter coarse-graining in time. Its variation with coarse graining in space has no definite sign. Results show that including the dynamics at scales below a few degrees reduces considerably the power input by air-sea interaction in regions of strongly non-linear ocean currents.<br>  When the ocean velocities are not considered in the shear calculation the power-input is considerably (up to threefold) increased. The dependence of the power input on coarse graining in space and time is close to being multiplicatively separable in all regions and for most of the coarse-graining domain considered.</p>

scholarly journals Dynamical Modulation of Wintertime Synoptic-Scale Cyclone Activity over the Japan Sea due to Changbai Mountain in the Korean Peninsula

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Hiroyuki Shimizu ◽  
Ryuichi Kawamura ◽  
Tetsuya Kawano ◽  
Satoshi Iizuka
Keyword(s):  
Korean Peninsula ◽  
Japan Sea ◽  
Changbai Mountain ◽  
Mountain Range ◽  
Synoptic Scale ◽  
Cyclone Activity ◽  
Low Level ◽  
Budget Analysis ◽  
Eddy Heat Flux ◽  
The Japan Sea

The dynamical impact of the Changbai Mountain Range in the Korean Peninsula on the extratropical cyclone activity over the Japan Sea in early winter is examined using the Weather Research Forecasting model. We have conducted two independent long-term integrations over 15 winter months (December only) from 2000 to 2014 with and without modified topography. The results show that the Changbai Mountain Range plays a vital role in increasing cyclone track frequency, low-level poleward eddy heat flux, and the local deepening rate over the Japan Sea through enhancement of the lower-tropospheric baroclinic zone (LTBZ). This mountain range gives rise to activation of the synoptic-scale cyclone activity over that region. From our case study on three typical cyclones, it is found that mesoscale structures in the vicinity of a cyclone’s center are dynamically modulated when it passes through the LTBZ and that cyclogenesis is triggered around that zone. A vorticity budget analysis shows that the stretching term relevant to enhanced low-level convergence plays a dominant role in intensifying cyclonic vorticities. We confirmed that the composite features of the three typical cases are consistent with the statistical ones of the dynamical modulation of the Changbai Mountain on synoptic-scale cyclone activity.

scholarly journals Climatological features of strong winds caused by extratropical cyclones around Japan

2021 ◽  
Author(s):  
Hidetaka Hirata
Keyword(s):  
Seasonal Change ◽  
Japan Sea ◽  
Conveyor Belt ◽  
Reanalysis Data ◽  
Extratropical Cyclones ◽  
The Pacific ◽  
Explosive Cyclones ◽  
The Japan Sea ◽  
Horizontal Pressure ◽  
Strong Winds

AbstractWe examined the climatological features of strong winds associated with extratropical cyclones around Japan during 40 seasons between November-April from 1979/80 to 2018/19 using reanalysis data. Our assessments revealed that the extratropical cyclones caused most of the strong winds around Japan (80-90%). Notably, the contribution of explosively developing extratropical cyclones is larger (70-80%). The strong winds are mainly related to the warm conveyor belt (WCB) and cold conveyor belt (CCB) inside the explosive cyclones. Moreover, the strong winds tend to be distributed widely over the southwestern quadrant of the cyclones. This is due to the intensification of the horizontal pressure gradient between the mature cyclones and the Siberian high extending from the Eurasia continent to Japan. We investigated the regionality of strong winds by highlighting the three areas with high frequencies of strong winds: the area around Hokkaido (i.e., the northernmost island of Japan [area A]), and the areas around the Japan Sea side (area B) and the Pacific Ocean side (area C) of the main island of Japan. The features of the seasonal change in the frequency of the strong winds differ in each area, which reflects the seasonal change in the activities of the explosive cyclones. Moreover, the CCB, the head of the CCB and WCB, and the CCB and WCB bring the strong winds to areas A, B, and C, respectively. The timing of the appearance of these windstorms during the lifecycles of typical cases highlighted in this study is consistent with that observed in Europe.

Mercury in the Kuroshio and Oyashio regions and the Japan Sea

Nature ◽  
1975 ◽  
Vol 258 (5532) ◽  
pp. 224-225 ◽  
Author(s):  
K. MATSUNAGA ◽  
M. NISHIMURA ◽  
S. KONISHI
Keyword(s):  
Japan Sea ◽  
The Japan Sea ◽  
The Kuroshio

scholarly journals Determining the dependence of the power supply to the ocean on the length and time scales of the dynamics between the meso-scale and the synoptic-scale, from satellite data

2020 ◽  
Author(s):  
Achim Wirth
Keyword(s):  
Gulf Stream ◽  
Kuroshio Extension ◽  
Surface Wind ◽  
Coarse Graining ◽  
Power Input ◽  
Ocean Dynamics ◽  
Synoptic Scale ◽  
Surface Wind Stress ◽  
Using Data ◽  
The Kuroshio

Abstract. The input of mechanical power to the ocean due to the surface wind-stress, in regions which correspond to different regimes of ocean dynamics, is considered using data from satellites observations. Its dependence on the coarse-graining range of the atmospheric and oceanic velocity in space from 0.5° to 10° and time from  6 h to 40 days is determined. In the area of the Gulf Stream and the Kuroshio extensions the dependence of the power-input on space-time coarse-graining varies over tenfold for the coarse-graining considered. It decreases over twofold for the Gulf Stream extension and threefold for the Kuroshio extension, when the coarse-graining length-scale passes from a few degrees to 0.5° at a temporal coarse-graining scale of a few days. It increases over threefold in the Gulf Stream and the Kuroshio extensions when the coarse-graining passes from several days to 6 h at a spatial coarse graining of a few degrees. The power input is found to increase monotonically with shorter coarse-graining in time. Its variation with coarse graining in space has no definite sign. Results show that including the dynamics at scales below a few degrees reduces considerably the power input by air-sea interaction in regions of strongly non-linear ocean currents. When the ocean velocities are not considered in the shear calculation the power-input is considerably (up to threefold) increased. The dependence of the power input on coarse graining in space and time is close to being multiplicatively separable in all regions and for most of the coarse-graining domain considered.

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