Asymmetric Relationship between the Meridional Displacement of the Asian Westerly Jet and the Silk Road Pattern

2018 ◽  
Vol 35 (4) ◽  
pp. 389-396 ◽  
Author(s):  
Xiaowei Hong ◽  
Riyu Lu ◽  
Shuanglin Li
Keyword(s):  
Silk Road ◽  
Westerly Jet ◽  
Meridional Displacement ◽  
Silk Road Pattern ◽  
The Silk Road

scholarly journals The Meridional Displacement of the Summer Asian Jet, Silk Road Pattern, and Tropical SST Anomalies

2016 ◽  
Vol 29 (10) ◽  
pp. 3753-3766 ◽  
Author(s):  
Xiaowei Hong ◽  
Riyu Lu
Keyword(s):  
Significant Relationship ◽  
Statistical Significance ◽  
Silk Road ◽  
Tropospheric Temperature ◽  
Temperature Anomalies ◽  
Western Asia ◽  
Meridional Displacement ◽  
Leading Mode ◽  
Silk Road Pattern ◽  
Sst Anomalies

Abstract The Silk Road pattern (SRP), which depicts the teleconnection pattern along the Asian jet, has been extensively investigated and commonly described as the leading mode of upper-tropospheric meridional wind anomalies in summer. In this study, the SRP is identified as having a significant relationship with the meridional displacement of the Asian jet (JMD), which manifests as the leading mode of upper-tropospheric zonal wind anomalies. This significant relationship is confirmed by the correlation coefficient between the indices for JMD and SRP, which is 0.39 and reaches statistical significance at the 0.01 level. When the Asian jet is in a northward (southward) displacement, the phase of SRP tends to be shown as anticyclonic (cyclonic) anomalies over western Asia and East Asia and cyclonic (anticyclonic) anomalies over Europe and central Asia. The authors propose an internal atmospheric mechanism for this relationship. In addition, it is found that the JMD is significantly affected by the tropical surface temperature anomalies. In particular, the negative (positive) SST anomalies in the tropical central and eastern Pacific of the preceding spring lead to significant cooler (warmer) tropical tropospheric temperatures in summer and may induce the northward (southward) displacement of the Asian jet through modifying the meridional gradient of tropospheric temperatures. The tropical tropospheric temperature anomalies may also affect the SRP through the JMD.

scholarly journals Interdecadal Variations of the Silk Road Pattern

2017 ◽  
Vol 30 (24) ◽  
pp. 9915-9932 ◽  
Author(s):  
Lin Wang ◽  
Peiqiang Xu ◽  
Wen Chen ◽  
Yong Liu
Keyword(s):  
Wave Train ◽  
Atlantic Multidecadal Oscillation ◽  
Teleconnection Pattern ◽  
Silk Road ◽  
Boreal Summer ◽  
Northeastern Asia ◽  
Western Asia ◽  
Silk Road Pattern ◽  
Decadal Climate ◽  
The Silk Road

Based on several reanalysis and observational datasets, this study suggests that the Silk Road pattern (SRP), a major teleconnection pattern stretching across Eurasia in the boreal summer, shows clear interdecadal variations that explain approximately 50% of its total variance. The interdecadal SRP features a strong barotropic wave train along the Asian subtropical jet, resembling its interannual counterpart. Additionally, it features a second weak wave train over the northern part of Eurasia, leading to larger meridional scale than its interannual counterpart. The interdecadal SRP contributes approximately 40% of the summer surface air temperature’s variance with little uncertainty and 10%–20% of the summer precipitation’s variance with greater uncertainty over large domains of Eurasia. The interdecadal SRP shows two regime shifts in 1972 and 1997. The latter shift explains over 40% of the observed rainfall reduction over northeastern Asia and over 40% of the observed warming over eastern Europe, western Asia, and northeastern Asia, highlighting its importance to the recent decadal climate variations over Eurasia. The Atlantic multidecadal oscillation (AMO) does not show a significant linear relationship with the interdecadal SRP. However, the Monte Carlo bootstrapping resampling analysis suggests that the positive (negative) phases of the spring and summer AMO significantly facilitate the occurrence of negative (positive) phases of the interdecadal SRP, implying plausible prediction potentials for the interdecadal variations of the SRP. The reported results are insensitive to the long-term trends in datasets and thereby have little relevance to externally forced climate change.

Potential Predictability of the Silk Road Pattern and the Role of SST as Inferred from Seasonal Hindcast Experiments of a Coupled Climate Model

2020 ◽  
Vol 33 (22) ◽  
pp. 9567-9580
Author(s):  
Ronald Kwan Kit Li ◽  
Chi Yung Tam ◽  
Ngar Cheung Lau ◽  
Soo Jin Sohn ◽  
Joong Bae Ahn
Keyword(s):  
North Atlantic ◽  
Silk Road ◽  
Potential Predictability ◽  
The North ◽  
Silk Road Pattern ◽  
The North Atlantic ◽  
Upper Level ◽  
The Silk Road ◽  
Wind Bias

AbstractThe Silk Road pattern (SR) is a leading mode of atmospheric circulation over midlatitude Eurasia in boreal summer. Its temporal phase is known to be unpredictable in many models. Previous studies have not reached a clear consensus on the role of sea surface temperature (SST) associated with SR. By comparing seasonal hindcasts from the Pusan National University (PNU) coupled general circulation model with reanalysis, we investigate if there are any sources of predictability originating from the SST. It was found that the PNU model cannot predict SR temporally. In fact, SR is associated with El Niño–Southern Oscillation (ENSO) in the model hindcasts, in contrast to reanalysis results in which SR is more associated with North Atlantic SST anomalies. The PNU system, however, shows potential predictability in SR associated with tropical Pacific SST. Bias in stationary Rossby waveguides is proposed as an explanation for the SR–ENSO relationship in hindcast runs. Model upper-level wind bias in the North Atlantic results in a less continuous waveguide connecting the North Atlantic to Asia, and may hinder wave propagations induced by North Atlantic SST to trigger SR. On the other hand, model upper-level wind bias in the subtropical western Pacific may favor westward propagation of zonally elongated waves from the ENSO region to trigger SR. This study implies that the role of SST with regard to SR can be substantially changed depending on the fidelity of model upper-level background winds.

Limitations of Seasonal Predictability for Summer Climate over East Asia and the Northwestern Pacific

2012 ◽  
Vol 25 (21) ◽  
pp. 7574-7589 ◽  
Author(s):  
Yu Kosaka ◽  
J. S. Chowdary ◽  
Shang-Ping Xie ◽  
Young-Mi Min ◽  
June-Yi Lee
Keyword(s):  
East Asia ◽  
El Niño ◽  
El Nino ◽  
Silk Road ◽  
Northwestern Pacific ◽  
Seasonal Predictability ◽  
Coupled Models ◽  
Summer Climate ◽  
Silk Road Pattern ◽  
The Silk Road

Predictability of summer climate anomalies over East Asia and the northwestern Pacific is investigated using observations and a multimodel hindcast ensemble initialized on 1 May for the recent 20–30 yr. Summertime East Asia is under the influence of the northwestern Pacific subtropical high (PASH). The Pacific–Japan (PJ) teleconnection pattern, a meridional dipole of sea level pressure variability, affects the northwestern PASH. The forecast models generally capture the association of the PJ pattern with the El Niño–Southern Oscillation (ENSO). The Silk Road pattern, a wave train along the summer Asian jet, is another dominant teleconnection that influences the northwestern PASH and East Asia. In contrast to the PJ pattern, observational analysis reveals a lack of correlations between the Silk Road pattern and ENSO. Coupled models cannot predict the temporal phase of the Silk Road pattern, despite their ability to reproduce its spatial structure as the leading mode of atmospheric internal variability. Thus, the pattern is rather unpredictable at monthly to seasonal lead, limiting the seasonal predictability for summer in East Asia. The anomalous summer of 2010 in East Asia is a case in point, illustrating the interference by the Silk Road pattern. Canonical anomalies associated with a decayed El Niño and developing La Niña would have the PJ pattern bring a cold summer to East Asia in 2010. In reality, the Silk Road pattern overwhelmed this tendency, bringing a record-breaking hot summer instead. A dynamical model experiment indicates that European blocking was instrumental in triggering the Silk Road pattern in the 2010 summer.

scholarly journals A Mechanism for the Recently Increased Interdecadal Variability of the Silk Road Pattern

2019 ◽  
Vol 32 (3) ◽  
pp. 717-736 ◽  
Author(s):  
Claudia Christine Stephan ◽  
Nicholas P. Klingaman ◽  
Andrew G. Turner
Keyword(s):  
South Asia ◽  
Time Scales ◽  
Prediction Models ◽  
Decadal Variability ◽  
Causal Effect ◽  
Vertical Motion ◽  
Silk Road ◽  
The North ◽  
Silk Road Pattern ◽  
The Silk Road

The Silk Road pattern (SRP) teleconnection manifests in summer over Eurasia, where it is associated with substantial temperature and precipitation anomalies. The SRP varies on interannual and decadal scales; reanalyses show an increase in its decadal variability around the mid-1970s. Understanding what drives this decadal variability is particularly important, because contemporary seasonal prediction models struggle to predict the phase of the SRP. Based on analysis of observations and multiple targeted numerical experiments, this study proposes a mechanism for decadal SRP variability. Causal effect network analysis confirms a positive feedback loop between the eastern portion of the SRP pattern and vertical motion over India on synoptic time scales. Anomalies over a larger region of subtropical South Asia can reinforce a background state that projects onto the positive or negative SRP through this mechanism. This effect is isolated and confirmed in targeted numerical simulations. The transition from weak to strong decadal variability in the mid-1970s is consistent with more spatially coherent interannual precipitation variability over subtropical South Asia. Furthermore, results suggest that oceanic variability does not directly force the SRP. Nevertheless, sea surface temperatures in the North Atlantic and the North Pacific may indirectly affect the SRP by modulating South Asian rainfall on decadal time scales.

scholarly journals Excitation Mechanisms of the Teleconnection Patterns Affecting the July Precipitation in Northwest China

2012 ◽  
Vol 25 (22) ◽  
pp. 7834-7851 ◽  
Author(s):  
Guosen Chen ◽  
Ronghui Huang
Keyword(s):  
Northwest China ◽  
Silk Road ◽  
Central Pacific ◽  
Tropical Rainfall ◽  
Teleconnection Patterns ◽  
Excitation Mechanisms ◽  
Silk Road Pattern ◽  
Rainfall Variations ◽  
The Silk Road ◽  
Tropical Heating

Abstract Using observational rainfall data and atmospheric reanalysis data, the precipitation variations in Northwest China during July and the corresponding atmospheric teleconnection patterns are studied. The results indicate that the leading modes of July precipitation variations in Northwest China are affected by the Silk Road pattern and the Europe–China (EC) pattern. The analysis suggests that the circumglobal teleconnection (CGT) could be considered as the interannual component of the Silk Road pattern. To investigate the excitation mechanisms for the CGT pattern and EC pattern on interannual time scales, the singular value decomposition (SVD) analysis is performed between 200-hPa meridional wind velocity over the region of (30°–60°N, 30°–130°E) and tropical rainfall between (15°S and 30°N). The results suggest that the tropical heating anomalies most responsible for the CGT pattern are located over the North Indian Ocean, and the tropical heating anomalies most responsible for EC pattern are located over equatorial central Pacific, Indonesia, and tropical Atlantic. The tropical heating anomalies excite the CGT pattern and EC pattern by inducing divergent flow at the upper troposphere, and the advections of vorticity by the divergent component of the flow act as effective Rossby wave sources. Further analysis indicates that the tropical rainfall anomalies responsible for the CGT pattern and EC pattern are the leading modes of tropical rainfall variations, and these modes of tropical rainfall variations are related to the SST anomalies.

scholarly journals Comparison between the interannual and decadal components of the Silk Road pattern

2018 ◽  
Vol 11 (3) ◽  
pp. 270-274 ◽  
Author(s):  
Xiao-Wei HONG ◽  
Shu-Hang XUE ◽  
Ri-Yu LU ◽  
Yu-Yun LIU
Keyword(s):  
Silk Road ◽  
Silk Road Pattern ◽  
The Silk Road

Interdecadal Variations in the Frequency of Persistent Hot Events in Boreal Summer over Midlatitude Eurasia

2019 ◽  
Vol 32 (16) ◽  
pp. 5161-5177 ◽  
Author(s):  
Ning Shi ◽  
Yicheng Wang ◽  
Xiaoqiong Wang ◽  
Pinyu Tian
Keyword(s):  
Time Scale ◽  
Wave Train ◽  
Northern China ◽  
Stationary Wave ◽  
Silk Road ◽  
Boreal Summer ◽  
Western Asia ◽  
Silk Road Pattern ◽  
The Silk Road ◽  
Circulation Changes

ABSTRACT Based on the daily Japanese 55-year Reanalysis (JRA-55) dataset, this study reveals that southern Europe/western Asia (SEWA) and northern China are two large-scale regions that have exhibited consistent interdecadal variations in the frequency of persistent hot events (PHEs). Over the past 58 summers, the period approximately from 1973 to 1996 represents an inactive period for the occurrence of PHEs over the two regions, whereas the antecedent and subsequent periods are active periods. At the subseasonal time scale, the regional PHEs over SEWA are characterized by quasi-stationary wave train anomalies aloft from the northwest Atlantic to Europe, while the regional PHEs over northern China are characterized by quasi-stationary wave train anomalies over the Eurasian continent. The persistence of the quasi-stationary anomalies is associated with the Rossby wave propagation. Moreover, the energy extraction from the basic flow is also favorable for their persistence. Our study reveals that the above typical circulation anomalies for the PHEs over both SEWA and northern China are in phase with the background circulation changes during the two active periods. Thus, the interdecadal changes in background circulation can modulate the frequency of PHEs over the two regions simultaneously. Further analysis reveals that the background circulation changes are closely related to the interdecadal variation in the Silk Road pattern based on their similarities in both spatial pattern and temporal variation. The sea surface temperature over four particular regions seems to facilitate the phase shifts in the Silk Road pattern on the interdecadal time scale.

Sign in / Sign up

Export Citation Format

Share Document