scholarly journals Concurrent variation between the East Asian subtropical jet and polar front jet during persistent snowstorm period in 2008 winter over southern China

2013 ◽  
Vol 118 (12) ◽  
pp. 6360-6373 ◽  
Author(s):  
Zhijie Liao ◽  
Yaocun Zhang
Keyword(s):  
Southern China ◽  
East Asian ◽  
Polar Front ◽  
Subtropical Jet ◽  
Polar Front Jet ◽  
Concurrent Variation

scholarly journals The Impact of the East Asian Subtropical Jet and Polar Front Jet on the Frequency of Spring Persistent Rainfall over Southern China in 1997–2011

2015 ◽  
Vol 28 (15) ◽  
pp. 6054-6066 ◽  
Author(s):  
Dan-Qing Huang ◽  
Jian Zhu ◽  
Yao-Cun Zhang ◽  
Jun Wang ◽  
Xue-Yuan Kuang
Keyword(s):  
Water Vapor ◽  
Southern China ◽  
East Asian ◽  
Lower Troposphere ◽  
Polar Front ◽  
Remarkable Feature ◽  
Upper Troposphere ◽  
Subtropical Jet ◽  
The Impact ◽  
Polar Front Jet

Abstract Spring persistent rainfall (SPR) over southern China has great impact on its society and economics. A remarkable feature of the SPR is high frequency. However, SPR frequency obviously decreases over the period of 1997–2011. In this study, the possible causes have been investigated from the perspective of the individual and concurrent effects of the East Asian subtropical jet (EASJ) and East Asian polar front jet (EAPJ). A close relationship is detected between SPR frequency and EASJ intensity (but not EAPJ intensity). Associated with strong EASJ, abundant water vapor is transported to southern China by the southwesterly flow, which may trigger the SPR. Additionally, frequencies of both strong EASJ and weak EAPJ events are positively correlated with SPR frequency. Further investigation of the concurrent effect indicates a significant positive correlation between the frequencies of SPR and the strong EASJ–weak EAPJ configuration. Associated with this configuration, southwesterly flow strengthens in the lower troposphere, while northerly wind weakens in the upper troposphere. This provides a dynamic and moist condition, as enhanced ascending motion and intensified convergence of abundant water vapor over southern China, which favors the SPR. All analyses suggest that the EASJ may play a dominant role in the SPR occurrence and that the EAPJ may play a modulation role. Finally, a possible mechanism maintaining the strong EASJ–weak EAPJ configuration is proposed. Significant cooling over the northeastern Tibetan Plateau may induce a cyclone anomaly in the upper troposphere, which could result in an accelerating EASJ and a decelerating EAPJ.

scholarly journals The Different Configurations of the East Asian Polar Front Jet and Subtropical Jet and the Associated Rainfall Anomalies over Eastern China in Summer

2014 ◽  
Vol 27 (21) ◽  
pp. 8205-8220 ◽  
Author(s):  
Dan-Qing Huang ◽  
Jian Zhu ◽  
Yao-Cun Zhang ◽  
An-Ning Huang
Keyword(s):  
Kinetic Energy ◽  
North Pacific ◽  
East Asian ◽  
Eastern China ◽  
Polar Front ◽  
La Niña ◽  
La Nina ◽  
Subtropical Jet ◽  
Polar Front Jet ◽  
Sst Anomalies

Abstract To investigate the concurrent impacts of the East Asian polar front jet (EAPJ) and subtropical jet (EASJ) on the summer rainfall over eastern China, positive (strengthened EAPJ with weakened EASJ) and negative (weakened EAPJ with strengthened EASJ) configurations are identified. In the positive configuration, rainfall decreases in the northern part of eastern China and increases in the southern part, vice versa in the negative configuration. The possible mechanisms maintaining the two jet configurations are further proposed from the perspectives of sea surface temperature (SST) and synoptic-scale transient eddy activities (STEA). In the positive configuration, meridional distributed cold–warm SST anomalies over the eastern North Pacific may induce regional circulation and meridional temperature gradient anomalies, which can strengthen the EAPJ and weaken the EASJ. The central Pacific La Niña–like SST anomalies are related with the Arctic vortexlike anomalies in the stratosphere, which may strengthen the EAPJ. Furthermore, the divergence of Eliassen–Palm vectors and the conversion from eddy kinetic energy to mean kinetic energy over the active region of the EAPJ may strengthen the EAPJ, vice versa for the weakened EASJ. In the negative configuration, associated with the warm SST anomalies over the western North Pacific, the enhanced convective activities may lead to a strengthened EASJ via meridional teleconnection. The teleconnection may be intensified by the strengthened easterly vertical shear. Additionally, eastern Pacific La Niña–like SST anomalies may intensify the Walker circulation, which may strengthen the EASJ via the Hadley circulation. The STEA-related anomalies are almost opposite those in the positive configuration, especially for the weakened EAPJ.

scholarly journals Seasonal Variations of the Synoptic-Scale Transient Eddy Activity and Polar Front Jet over East Asia

2010 ◽  
Vol 23 (12) ◽  
pp. 3222-3233 ◽  
Author(s):  
Xuejuan Ren ◽  
Xiuqun Yang ◽  
Cuijiao Chu
Keyword(s):  
East Asia ◽  
Seasonal Variations ◽  
East Asian ◽  
Polar Front ◽  
Transient Eddy ◽  
Synoptic Scale ◽  
Wind Fields ◽  
The North ◽  
Upper Level ◽  
Polar Front Jet

Abstract Seasonal variations of the synoptic-scale transient eddy activity (STEA) and the jet streams over East Asia are examined through analysis of the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data. Extracted from the 6-hourly upper-level wind fields, the distribution of the jet core numbers exhibits a distinct geographical border for the East Asian subtropical jet (EASJ) and the East Asian polar front jet (EAPJ) at the latitudes of the northern Tibetan Plateau (TP). In the cool seasons, two branches of the STEA and low-level baroclinicity exist over the East Asian landmass, accompanied by the two-jet state of the EASJ and EAPJ. In the warm seasons, a single jet pattern of the EASJ along the north flank of the TP is accompanied by the weakened STEA over the mid- to high latitudes of East Asia. Further analysis shows two distinct features of the seasonal variations of the STEA over East Asia, compared with that over the North Pacific. First, during the transitional period of April–June, the main STEA band over East Asia migrates northward dramatically, in conjunction with the EAPJ shifting in the same direction. Second, both the upper-level STEA and the lower-level baroclinicity poleward of the TP are prosperous in spring. The relationship between the STEA, baroclinicity, vertical wind shear, and static stability in the EAPJ region in different seasons is further investigated. It is found that in addition to the time-mean wind fields, the rapid increase in the sensible heat flux poleward side of the TP region in spring and the associated boundary layer processes are partially responsible for the spring prosperity of the local baroclinicity and the STEA.

An Evaluation of Some Condensation Trail Observations

1955 ◽  
Vol 36 (2) ◽  
pp. 73-79
Author(s):  
Hal H. Dunning ◽  
N. E. La Seur
Keyword(s):  
Lower Stratosphere ◽  
Theoretical Work ◽  
Polar Front ◽  
Jet Streams ◽  
Upper Troposphere ◽  
Subtropical Jet ◽  
Synoptic Features ◽  
Trail Formation ◽  
Polar Front Jet

Observations made on ten routine B-47 training missions are used to evaluate present theoretical work on formation of exhaust condensation trails, and these observations are then correlated with the structure of the upper troposphere and lower stratosphere, to determine synoptic features typically associated with favorable and unfavorable conditions for trail formation For the altitudes considered broad areas of trail formation were found to occur only between the polar front and the sub-tropical jet streams. Broad areas unfavorable to trail formation were found to be located on the cyclonic shear side of the polar front jet and on the anticyclonic shear side of the subtropical jet. Agreement between these observations and theory is good.

scholarly journals The combined effect of two westerly jet waveguides on heavy haze in the North China Plain in November and December 2015

2020 ◽  
Vol 20 (8) ◽  
pp. 4667-4680 ◽  
Author(s):  
Xiadong An ◽  
Lifang Sheng ◽  
Qian Liu ◽  
Chun Li ◽  
Yang Gao ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Rossby Waves ◽  
Southern China ◽  
Polar Front ◽  
The North ◽  
Westerly Jet ◽  
The North China Plain ◽  
Polar Front Jet ◽  
Subtropical Westerly Jet

Abstract. Severe haze occurred in the North China Plain (NCP) from November to December 2015, with a wide spatial range and long duration. In this paper, the combined effect of the anomalous stationary Rossby waves within two westerly jet waveguides on this haze event in the NCP is investigated based on observational visibility data and NCEP/NCAR reanalysis data. The results show that circulation anomalies in Eurasia caused by the propagation of anomalous stationary Rossby wave energy along two waveguides within the westerly jet originating from the Mediterranean were responsible for haze formation in the NCP. The Rossby waves propagated eastward along the subtropical westerly jet and the polar front jet, causing an anomalous anticyclone over the Sea of Japan and anticyclonic wind shear at 850 hPa over the NCP, which enhanced the anomalous descent in the middle and lower troposphere and subsequently resulted in a stable lower atmosphere. Furthermore, the anomalous stationary Rossby waves propagating along the polar front jet weakened the East Asia trough and Ural ridge and strengthened the anomalous southerly wind at 850 hPa over the coastal areas of eastern China, decelerating the East Asia winter monsoon. The above meteorological conditions modulated haze accumulation in November and December 2015. Meanwhile, continuous rainfall related to ascending motion due to Rossby wave propagation along the waveguide provided by the subtropical westerly jet occurred in a large area of southern China. The associated latent heat release acted as a heat source, intensifying the ascending motion over southern China so that the descending motion over the NCP was strengthened, favoring the maintenance of severe haze. This study elucidates the formation and maintenance mechanism of large-scale haze in the NCP in late fall and boreal winter.

scholarly journals Mid-Holocene variability of the East Asian monsoon based on bulk organic δ13C and C/N records from the Pearl River estuary, southern China

The Holocene ◽  
2011 ◽  
Vol 22 (6) ◽  
pp. 705-715 ◽  
Author(s):  
Fengling Yu ◽  
Yongqiang Zong ◽  
Jeremy M Lloyd ◽  
Melanie J Leng ◽  
Adam D Switzer ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Southern China ◽  
East Asian ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
The Pearl River Estuary ◽  
The Pearl River
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