Activity Characteristics of the East Asian Trough in CMIP5 Models

Chen, Xiong; Xing, Lei; Li, Xin; Li, Mingyang; Yang, Minghao

doi:10.3390/atmos9020067

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…We conducted the empirical orthogonal function (EOF) technique in the MedT region (25°-55°N, 0°-65°E) to extract the dominant modes and principal components (PCs) of the 500-hPa geopotential height variability of the MedT. The EOF analysis has been widely used in obtaining the dominant modes of atmospheric fields of various monsoon systems, such as the East Asian winter monsoon (Chen et al, 2014;Shi, 2021), EAT (Wang et al, 2009;Leung and Zhou, 2015;Chen et al, 2018), and MedT (Sen et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

Influence of the interannual variability of the Kuroshio Extension on the Mediterranean trough in the cold season

Jiang

Sun²,

Li³

et al. 2022

Front. Mar. Sci.

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The impacts of the Kuroshio Extension (KE) interannual fluctuation on the Mediterranean trough (MedT) and associated Euro-Mediterranean climate in wintertime are analyzed in this study. It appears that when the KE index is positive (corresponds to a stable KE state with sharp sea surface temperature front and subsided oceanic eddies), the MedT is observed to be stronger in the west of its climatological position, resulting in a colder condition to the west of the Black Sea and more precipitation in the East Mediterranean and Anatolia Plateau. The opposite atmospheric pattern holds when the KE index is negative (unstable KE state). The empirical orthogonal function analysis is performed on 500-hPa geopotential height to obtain the dominant modes of MedT. The results show the KE index is significantly correlated with the intensity and zonal displacement of MedT, with correlation coefficients of 0.57 and 0.40, respectively. The low-frequency Rossby wave activity and high-frequency eddies are revealed as the prominent contributors to this co-variability between the KE and MedT. The upward turbulent heat flux transport from the ocean to the atmosphere strengthened by the stable KE activates the Rossby waves propagating upward and westward to the MedT region, contributing to approximately 30% of the MedT deepening. Meanwhile, the KE-driven Rossby waves intensify the background baroclinicity to the north of the Mediterranean Sea and thus enhance the transient eddy activity, consequently leading to another 20% of the MedT amplification via the eddy–mean flow interaction. The findings highlight the impacts of the KE state on the meteorological conditions in the Euro-Mediterranean region, which can potentially optimize the forecast accuracies of the MedT and associated Euro-Mediterranean climate variability.

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Section: Methodsmentioning

confidence: 99%

Influence of the interannual variability of the Kuroshio Extension on the Mediterranean trough in the cold season

Jiang

Sun²,

Li³

et al. 2022

Front. Mar. Sci.

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“…Before and during the lifespan of this MCS, the northeastern coastal region of China was dominated by a deep, southwestward extending trough at the middle‐to‐upper levels, which could be traced back to 1200 UTC 26 April 2015 (Figure 1a). In the colder half of the year, the coastal region of East Asian is often occupied by a deep, semipermanent trough that is commonly known as the East Asian Trough (EAT) (Chen et al, 2018; Song et al, 2016; Wang et al, 2009). At the time, Jiangsu Province was located ahead of the upper‐level trough line and at the front‐left exit region of the East Asia upper‐tropospheric jet stream (EAJS) (Figure 2a).…”

Section: Case Overviewmentioning

confidence: 99%

The Initiation and Organization of a Severe Hail‐Producing Mesoscale Convective System in East China: A Numerical Study

2020

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The initiation and organization of a long‐duration hail‐producing mesoscale convective system (MCS) in eastern China are investigated using convection‐allowing simulations at 3‐km grid spacing with the Advanced Regional Prediction System. The lifecycle of this MCS is characterized by two stages. In the first stage, a series of convective storms are initiated along the northwest border of Jiangsu Provinces. These storms organize into a northwest southeast line as they moved southeastward, eventually organizing into an eastward moving bow‐echo structure during the second stage. Our analyses show that the storms initiate along a northwest‐southeast oriented convergence boundary set up between two low‐level mesoscale vortices, one to the northwest of Jiangsu Province and one over the East China Sea. Comparisons between the fake‐dry and control simulations show that the rearward (westward) spreading of a cold pool from another MCS proceeding the hail‐producing MCS plays a key role in generating and enhancing the vortex over Eastern China Sea. The tilting of baroclinically generated horizontal vorticity along the edge of the cold outflow creates a cyclonic and anticyclonic vortex couplet. The cyclonic vortex becomes the dominant East China Sea vortex as it is superposed onto the background cyclonic circulation. This cold outflow‐induced vortex also has strong impacts on the later organization of the hail‐producing MCS, leading to the eventual establishment of a bow‐echo structure. Finally, a three‐stage conceptual model for the initiation and organization of the long‐lasting multicellular MCS is proposed, and the understanding on the complex interactions between two MCSs will be helpful to operational forecasters.

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“…On the seasonal time scale, the variation of the EAT is closely related to the establishment and retreat of the East Asian winter monsoon (EAWM) circulation (Academia Sinica, 1957; Ye and Zhu, 1958). Whereas, the interannual variation of the EAT reflects the intensity of the EAWM (Chen et al ., 2018). Specifically, a deep EAT facilitates strong EAWM, which leads to cold anomalies over East Asia (Cui and Sun, 1999; Chen et al ., 2005; Wang et al ., 2009a; Huang et al ., 2012), a weak storm track over North Pacific (Lee et al ., 2010), and less (enhanced) precipitation over southern China (the Maritime Continent) (Wang and Chen, 2010; Wang and Feng, 2011).…”

Section: Introductionmentioning

confidence: 99%

A dynamical and numerical study of the effects of the topography of the Tibetan Plateau and westerly wind speed on the East Asian Trough

Liang

Gao

et al. 2021

Intl Journal of Climatology

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The effects of the topography of the Tibetan Plateau (TP) and westerly wind speed on the East Asian Trough (EAT) is discussed with analysis using a dynamical model, and verified with numerical experiments based on real cases. The dynamical model utilizes a complex terrain function to approximate the TP topography, and derives a stream function generated by the TP terrain. The numerical experiments used for the verification consider the influence of different TP terrain heights and westerly wind speeds. The results show that the topography of the TP has a prominent contribution to the intensity of the EAT, but little effect on its position. The topography of the TP in the westerly winds causes a low‐pressure trough to its east, which promotes a deepening of the EAT to the east side of the TP. In contrast, in the context of the TP, westerly wind speed has an important influence on the position of the EAT, but a minor impact on the deepening of the EAT. A larger westerly wind speed causes a more eastern position of the EAT. These findings indicate that the combination of large‐scale topography and westerly wind speed plays a key role in the evolution of the EAT, in the terms of intensity and position.

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Activity Characteristics of the East Asian Trough in CMIP5 Models

Cited by 4 publications

References 22 publications

Influence of the interannual variability of the Kuroshio Extension on the Mediterranean trough in the cold season

Influence of the interannual variability of the Kuroshio Extension on the Mediterranean trough in the cold season

The Initiation and Organization of a Severe Hail‐Producing Mesoscale Convective System in East China: A Numerical Study

A dynamical and numerical study of the effects of the topography of the Tibetan Plateau and westerly wind speed on the East Asian Trough

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