The early summer seasonal change of Large-Scale circulation over east asia and its relation to change of the frontal features and frontal rainfall environment during 1991 summer

1995 ◽  
Vol 12 (2) ◽  
pp. 151-176 ◽  
Author(s):  
Gong-Wang Si ◽  
Kuranoshin Kato ◽  
Takao Takeda
Keyword(s):  
East Asia ◽  
Seasonal Change ◽  
Large Scale ◽  
Early Summer ◽  
Large Scale Circulation

Circulation Features Associated with the Record-Breaking Rainfall over South China in June 2017

2018 ◽  
Vol 31 (18) ◽  
pp. 7209-7224 ◽  
Author(s):  
Jianqi Sun ◽  
Jing Ming ◽  
Mengqi Zhang ◽  
Shui Yu
Keyword(s):  
East Asia ◽  
South China ◽  
North Atlantic ◽  
Large Scale ◽  
Wave Train ◽  
Western Pacific Subtropical High ◽  
Early Summer ◽  
Intense Rainfall ◽  
Maritime Continent ◽  
Anomalous Anticyclone

In June 2017, south China suffered from intense rainfall that broke the record spanning the previous 70 years. In this study, the large-scale circulations associated with the south China June rainfall are analyzed. The results show that the anomalous Pacific–Japan (PJ) pattern is a direct influence on south China June rainfall or East Asian early summer rainfall. In addition, the Australian high was the strongest in June 2017 during the past 70 years, which can increase the equatorward flow to northern Australia and activate convection over the Maritime Continent. Enhanced convection over the Maritime Continent can further enhance local meridional circulation along East Asia, engendering downward motion over the tropical western North Pacific and enhancing the western Pacific subtropical high (WPSH) and upward motion over south China, which increases the rainfall therein. In addition, a strong wave train pattern associated with North Atlantic air–sea interaction was observed in June 2017 at Northern Hemispheric mid- to high latitudes; it originated from the North Atlantic and propagated eastward to East Asia, resulting in an anomalous anticyclone over the Mongolian–Baikal Lake region. This anomalous anticyclone produced strong northerly winds over East Asia that encountered the southerly associated with the WPSH over south China, thereby favoring intense rainfall over the region. Case studies of June 2017 and climate research based on data during 1979–2017 and 1948–2017 indicate that the extremities of the atmospheric circulation over south Europe and Australian high and their coupling with the PJ pattern could be responsible for the record-breaking south China rainfall in June 2017.

Large-Scale Circulation Anomalies Associated with Extreme Heat in South Korea and Southern–Central Japan

2020 ◽  
Author(s):  
Ke Xu
Keyword(s):  
South Korea ◽  
East Asia ◽  
Large Scale ◽  
Extreme Heat ◽  
Central Japan ◽  
Large Scale Circulation ◽  
Westerly Jet ◽  
Anomalous Anticyclone ◽  
Wave Trains ◽  
Circulation Anomalies

<p>    The large-scale circulation anomalies associated with extreme heat (EH) in South Korea and southern–central Japan are examined using data during the time period 1979–2016. Statistical analysis indicates that EH days in these two regions are concentrated in July and August and tend to occur simultaneously. These EH days are therefore combined to explore the physical mechanisms leading to their occurrence. The composite results indicate that the anomalous atmospheric warming during EH days is dominantly caused by a significant subsidence anomaly, which is associated with a deep anomalous anticyclone over East Asia. Further investigation of the evolution of circulation anomalies suggests that the anomalous anticyclone over East Asia related to EH is primarily initiated by wave trains originating from upstream regions, which propagate eastward along the Asian westerly jet in the upper troposphere. These wave trains can be categorized into two types that are characterized by the precursor anticyclonic and cyclonic anomalies, respectively, over central Asia. The distinction between these two types of wave train can be explained by the wavenumbers of the Rossby waves, which are modulated by both the intensity and the shape of the Asian westerly jet as the background basic flow.</p>

Precipitation Characteristics over East Asia in Early Summer: Effects of the Subtropical Jet and Lower-Tropospheric Convective Instability

2017 ◽  
Vol 30 (20) ◽  
pp. 8127-8147 ◽  
Author(s):  
Chie Yokoyama ◽  
Yukari N. Takayabu ◽  
Takeshi Horinouchi
Keyword(s):  
East Asia ◽  
Convective Instability ◽  
Large Scale ◽  
Early Summer ◽  
Shallow Convection ◽  
The South ◽  
Subtropical Jet ◽  
High Dependency ◽  
Precipitation Characteristics ◽  
Stratiform Precipitation

Abstract A quasi-stationary front, called the baiu front, often appears during the early-summer rainy season in East Asia (baiu in Japan). The present study examines how precipitation characteristics during the baiu season are determined by the large-scale environment, using satellite observation three-dimensional precipitation data. Emphasis is placed on the effect of subtropical jet (STJ) and lower-tropospheric convective instability (LCI). A rainband appears together with a deep moisture convergence to the south of the STJ. Two types of mesoscale rainfall events (REs; contiguous rainfall areas), which are grouped by the stratiform precipitation ratio (SPR; stratiform precipitation over total precipitation), are identified: moderately stratiform REs (SPR of 0%–80%) representing tropical organized precipitation systems and highly stratiform REs (SPR of 80%–100%) representing midlatitude precipitation systems associated with extratropical cyclones. As the STJ becomes strong, rainfall from both types of mesoscale precipitation systems increases, with a distinct eastward extension of a midtropospheric moist region. In contrast, small systems appear regardless of the STJ, with high dependency on the LCI. The results indicate that the STJ plays a role in moistening the midtroposphere owing to ascent associated with secondary circulation to the south of the STJ, producing environments favorable for organized precipitation systems in the southern part of the rainband. The horizontal moisture flux convergence may also contribute to precipitation just along the STJ. On the other hand, the LCI plays a role in generating shallow convection. In high-LCI conditions, deep convection can occur without the aid of mesoscale organization.

scholarly journals Impact of orbitally-driven seasonal insolation changes on Afro-Asian summer monsoons through the Holocene

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Chi-Hua Wu ◽  
Pei-Chia Tsai
Keyword(s):  
East Asia ◽  
Large Scale ◽  
Late Summer ◽  
Early Summer ◽  
Valuable Insight ◽  
The Holocene ◽  
Upper Troposphere ◽  
Asian Summer ◽  
Seasonal Diversity ◽  
Insight Into

AbstractUnderstanding what drives a shift of the Afro–Asian summer monsoons from the continents to oceanic regions provides valuable insight into climate dynamics, changes, and modeling. Here we use data–model synthesis to focus on the differential seasonal responses of solar insolation and monsoons to orbital changes in the Holocene. We observe coordinated and stepwise seasonal evolution of summer monsoons across the mid-Holocene, suggesting the strengthening of the midlatitude jet stream as a bridge in the upper troposphere. Prior to the mid-Holocene, insolation had decreased considerably in early summer; the continental monsoons migrated southeastward, which corresponded to a more pronounced rainy season in coastal East Asia. In late summer, insolation did not decrease until the mid-Holocene. The continued weakening of the continental monsoons, combined with weakened insolation, rapidly enhanced the intrinsic dynamics over East Asia–Western North Pacific and accelerated a large-scale migration of the monsoon, suggesting orbital control of seasonal diversity.

scholarly journals Implications of a Decadal Climate Shift over East Asia in Winter: A Modeling Study

2010 ◽  
Vol 23 (18) ◽  
pp. 4989-5001 ◽  
Author(s):  
Song-You Hong ◽  
Yoo-Bin Yhang
Keyword(s):  
Climate Change ◽  
East Asia ◽  
Large Scale ◽  
Hydrological Cycle ◽  
East Asian ◽  
Lower Troposphere ◽  
Large Scale Circulation ◽  
Winter Climate ◽  
Climate Shift ◽  
Decadal Climate

Abstract This study investigates a decadal climate shift over East Asia in winter, focusing on the changes in hydrological cycle as well as large-scale circulation using the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM). The RSM is forced by perfect boundary conditions for winter (December–February) from 1979 to 2007. Analyses for two separate periods (1979–87 and 1999–2007) are performed to investigate the regional climate model’s ability to simulate climate change in precipitation as well as large-scale circulation. The RSM reproduces differences in large-scale features associated with winter climate change over East Asia when the winter monsoon is modulated on decadal time scales with its weakening pattern observed since the late 1980s. The model adequately reproduces a weakening of the Siberian high and shallowness of the Aleutian low in the lower troposphere and a weakened East Asian coastal trough and East Asian jet in the upper troposphere during 1999–2007, as compared to the first nine winters of 1979–87. Conversely, the decadal shift in precipitation is not well reproduced by the model. The model is capable of reproducing the power spectrum of daily precipitation with maxima at 8.5 days and 45 days in 1979–87, whereas widely spread peaks in 1999–2007 are not captured. The increase of precipitation due to parameterized convection is prominent. This study shows that the dynamical numerical model has a limited capability to reproduce the wintertime hydrological climate over East Asia associated with global warming in recent years.

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