On Northern Hemisphere Wave Patterns Associated with Winter Rainfall Events in China

Stephan, Claudia Christine; Ng, Yan Ho; Klingaman, Nicholas P.

doi:10.1007/s00376-018-7267-7

Cited by 7 publications

(6 citation statements)

References 23 publications

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“…These experiments were previously analyzed by Stephan et al (2018b), where more details of the simulations are given. Stephan et al (2018a) showed that these simulations well capture extratropical Rossby wave propagation over Eurasia.…”

Section: Simulationsmentioning

confidence: 75%

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

2019

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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.

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Section: Simulationsmentioning

confidence: 75%

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

2019

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“…Orthogonal Teleconnections (EOT) has been applied in China (Stephan et al, 2017a(Stephan et al, , 2017b(Stephan et al, , 2018.…”

Section: Analysis Of the Dipole-based Statistical Modelmentioning

confidence: 99%

Seasonal rainfall forecasting for the Yangtze River basin using statistical and dynamical models

Qian

Chen

et al. 2019

Intl Journal of Climatology

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Summer monsoon rainfall forecasting in the Yangtze River basin is highly valuable for water resource management and for the control of floods and droughts. However, improving the accuracy of seasonal forecasting remains a challenge. In this study, a statistical model and four dynamical global circulation models (GCMs) are applied to conduct seasonal rainfall forecasts for the Yangtze River basin. The statistical forecasts are achieved by establishing a linear regression relationship between the sea surface temperature (SST) and rainfall. The dynamical forecasts are achieved by downscaling the rainfall predicted by the four GCMs at the monthly and seasonal scales. Historical data of monthly SST and GCM hindcasts from 1982-2010 are used to make the forecast. The results show that the SST-based statistical model generally outperforms the GCM simulations, with higher forecasting accuracy that extends to longer lead times of up to 12 months. The SST statistical model achieves a correlation coefficient up to 0.75 and the lowest mean relative error of 6%. In contrast, the GCMs exhibit a sharply decreasing forecast accuracy with lead times longer than 1 month. Accordingly, the SST statistical model can provide reliable guidance for the seasonal rainfall forecasts in the Yangtze River basin, while the results of GCM simulations could serve as a reference for shorter lead times. Extensive scope exists for further improving the rainfall forecasting accuracy of GCM simulations.

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“…The Silk Road pattern (SRP) is a large-scale summertime teleconnection of the upper-level winds over Europe and Asia (Enomoto et al 2003). It is a manifestation of the Rossby waves that form in the subtropical westerly jet (SWJ), where the SWJ acts as a waveguide due to the meridional change in zonal winds (Hoskins and Karoly 1981, Enomoto et al 2003, Stephan et al 2018. It can be considered as the Asian branch of the circumglobal teleconnection (Ding and Wang 2005).…”

Section: Introductionmentioning

confidence: 99%

Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

Muetzelfeldt

Schiemann

Turner

et al. 2023

Environ. Res. Commun.

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The Silk Road pattern (SRP) is analysed on intraseasonal timescales over summer using empirical orthogonal functions (EOFs) of the meridional wind at 200 hPa. The ﬁrst two principal components explain almost equal amounts of variance, hence both are required to represent the intraseasonal SRP. The associated spatial loadings are 90° out of phase with each other, providing evidence that propagating oscillations are a natural mode of variability of the intraseasonal SRP. This is supported by Hovmöller diagrams of the meridional wind at 200 hPa and by phase diagrams of the ﬁrst two EOFs, which both show a predominantly eastward-propagating oscillation. The oscillations are identiﬁed as plausibly being Rossby waves by means of waveguide theory. The subtropical westerly jet and East Asian rainfall patterns are found to be dependent on the phase of the oscillation: wet anomalies occur to the east of troughs in the jet, which are also regions where local jet entrances cause upper-level divergence via an ageostrophic circulation. Dry anomalies occur to the west of troughs, which are regions of upper-level convergence. The time-delayed location of the summer Mei Yu front relative to its climatology is dependent on the phase of the oscillation: when there is an upper-level trough located over the Korean Peninsula, the Mei Yu front is likely to be located further north than normal 3–8 days later, before returning to its climatological position. This suggests that the phase of the intraseasonal SRP acts as a potential source of predictability of the location of the Mei Yu front, which might allow for better prediction of the associated rains.

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On Northern Hemisphere Wave Patterns Associated with Winter Rainfall Events in China

Cited by 7 publications

References 23 publications

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

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

Seasonal rainfall forecasting for the Yangtze River basin using statistical and dynamical models

Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

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