Diagnostic comparison of wintertime East Asian subtropical jet and polar-front jet: Large-scale characteristics and transient eddy activities

2011 ◽  
Vol 25 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Xuejuan Ren ◽  
Xiuqun Yang ◽  
Tianjun Zhou ◽  
Jiabei Fang
Keyword(s):  
Large Scale ◽  
East Asian ◽  
Polar Front ◽  
Transient Eddy ◽  
Subtropical Jet ◽  
Scale Characteristics ◽  
Polar Front Jet

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.

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.

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.

Parts of South-east Asia may adopt nuclear post-2030

2021 ◽  
Keyword(s):  
East Asia ◽  
Nuclear Power ◽  
Large Scale ◽  
East Asian ◽  
Energy Development ◽  
South East Asia ◽  
Asian Countries ◽  
Content Type ◽  
Electricity Grid ◽  
Renewable Energy Development

Significance It is the only country in South-east Asia with a large-scale nuclear plant, although this was never loaded with fuel. Other countries in the region have tentative plans to develop nuclear power programmes. Impacts The current absence of nuclear power programmes will help avert the diversion of capital from renewable energy development in the region. South-east Asian countries with small, non-power reactors, built for research, will try to maintain these facilities. Across the region, the need for electricity grid investment will increase as more decentralised generation sources are deployed.

scholarly journals Small-scale characteristics of extremely high latitude aurora

2009 ◽  
Vol 27 (9) ◽  
pp. 3335-3347 ◽  
Author(s):  
J. A. Cumnock ◽  
L. G. Blomberg ◽  
A. Kullen ◽  
T. Karlsson ◽  
Keyword(s):  
High Latitude ◽  
Large Scale ◽  
Small Scale ◽  
Strong Correlations ◽  
Polar Cap ◽  
Plasma Flows ◽  
Ionospheric Convection ◽  
Local Closure ◽  
Scale Characteristics

Abstract. We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF By. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.

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