Interdecadal Variations of the East Asian Winter Monsoon and Their Association with Quasi-Stationary Planetary Wave Activity

Wang, Lin; Huang, Ronghui; Gu, Li; Chen, Wen; Liu, Kang

doi:10.1175/2009jcli2973.1

Cited by 182 publications

(123 citation statements)

References 31 publications

(38 reference statements)

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“…Climatologically last days of CDD appeared in later half of winter monsoon (see Supplement-2). Recently, Wang et al (2009) found that the East Asian winter monsoon became weaker since around the late 1980s. The weakening of the East Asian winter monsoon suggests a decrease of frequency and/or intensity of the cold surge from Siberia into the South China Sea and the Philippine Sea.…”

Section: Resultsmentioning

confidence: 99%

Trends in Precipitation Extremes over Southeast Asia

Endo

Matsumoto

Lwin³

2009

SOLA

142

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The authors investigate trends in precipitation extremes using daily precipitation data from Southeast Asian countries during 1950s to 2000s. Number of wet days, defined by a day with at least 1 mm of precipitation, tends to decrease over these countries, while average precipitation intensity of wet days shows an increasing trend. Heavy precipitation indices, which are defined by precipitation amount and percentile, demonstrate that the number of stations with significant upward trend is larger than that with significant downward trend. Heavy precipitation increases in southern Vietnam, northern part of Myanmar, and the Visayas and Luzon Islands in the Philippines, while heavy precipitation decreases in northern Vietnam. Annual maximum number of consecutive dry days decreases in the region where winter monsoon precipitation dominates. Decrease of precipitation event in the dry season is suggested in Myanmar.

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Section: Resultsmentioning

confidence: 99%

Trends in Precipitation Extremes over Southeast Asia

Endo

Matsumoto

Lwin³

2009

SOLA

142

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“…According to Wang and Chen (2010), EAWMIs can be classified into four types: (1) east-west pressure gradient indices (e.g., Wu and Wang 2002;Chan and Li 2004;Wang et al 2009b;Wang and Chen 2014), (2) low-level meridional wind indices (e.g., Ji et al 1997;Lu and Chan 1999;Yang et al 2002), (3) upper-level zonal wind shear indices (e.g., Jhun and Lee 2004;Zhu 2008;Li and Yang 2010), and (4) EA trough indices (e.g., Wang et al 2009a;Wang and He 2012). The EAWM-related circulation and air temperature anomalies are well delineated by these indices (Ji et al 1997;Jhun and Lee 2004;Chen 2010, 2014).…”

Section: Introductionmentioning

confidence: 99%

Winter climate changes over East Asian region under RCP scenarios using East Asian winter monsoon indices

2016

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that resemble the composite strong winter monsoon pattern are simulated more or less weakly in CMIP5 compared to the observation. However, the regressed fields of sea level pressure, surface air temperature, 500-hPa geopotential height, and 300-hPa zonal wind are well established with pattern correlations above 0.83 between CMIP5 and observation data. The differences between RCPs and Historical indicate strong warming, which increases with latitude, ranging from 1 to 5 °C under RCP4.5 and from 3 to 7 °C under RCP8.5 in the East Asian region. The anomalous southerly winds generally become stronger, implying weaker EAWMs in both scenarios. These features are also identified with fields regressed onto the indices in RCPs. The future projections reveal that the interannual variability of the indices will be maintained with an intensity similar to that of the present. The correlation between monsoon indices and Arctic Oscillation increases over time. On the other hand, the correlation between monsoon indices and North Atlantic Oscillation decreases.

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“…However, as seen in Fig. 1, and as suggested by previous studies (Hu and Tung, 2002;Wang et al, 2009), the amplitudes of planetary waves in the NH stratosphere always appear to be much larger than those in the troposphere, and thus, in this study, it is inadequate to compare the absolute amplitude values between stratospheric and tropospheric planetary waves and to show their respective dominant structures. Therefore, at a given vertical level, we normalise the amplitude of each wave component (k, l) by dividing the amplitude values by the maximum value among them, and refer them to as the normalised amplitudes.…”

Section: Spatial Spectral Expansionmentioning

confidence: 56%

“…Meanwhile, the PWV is important for the northÁsouth transport of momentum, heat and mass (Chen and Huang, 2002;Randel et al, 2002), and is related to regional and hemispheric climates (Chen et al, 2005;Wang et al, 2009). Previous theoretical studies have suggested a significant influence of mid-latitude westerly flow on the propagation and evolution of planetary waves (Rossby, 1939;Yeh, 1949;Kuo, 1956;Charney and Drazin, 1961).…”

Section: Introductionmentioning

confidence: 99%

Contrasting meridional structures of stratospheric and tropospheric planetary wave variability in the Northern Hemisphere

Sun

Jin

et al. 2014

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C TThe meridional structures of stratospheric and tropospheric planetary wave variability (PWV) over the Northern Hemisphere (NH) extratropics were investigated and compared using reanalysis data. By performing the spherical double Fourier series expansion of geopotential height data, the horizontal structures of PWV at each vertical level could be examined in the two-dimensional (2D) wavenumber (zonal and meridional wavenumbers) space. Comparing the amplitudes of wave components during the last three decades, the results suggested that the structures of PWV in the NH troposphere significantly differ from the stratospheric counterparts. The PWV in the troposphere shows multiple meridional wave-like structures, most pronounced for the meridional dipole; while in contrast, PWV in the stratosphere mainly shows large-scale zonal wave patterns, dominated by zonal waves 1 and 2, and have little wave-like fluctuation in the latitudinal direction. The dominant patterns of the NH PWV also show contrasting features of meridional structure between the stratosphere and the troposphere. As represented in the 2D wavenumber space, the leading two empirical orthogonal functions of PWV in the stratosphere largely exhibit the zonal wave 1 pattern, while those in the troposphere clearly show meridional wave-like structures and are dominated by the dipole. The refractive index was derived based on the zonal mean basic state to qualitatively interpret the observational findings. The results suggested that the basic state in the NH troposphere is much more favourable for latitudinally propagating stationary waves than the stratosphere. The difference in meridional structure between stratospheric and tropospheric planetary waves can be well captured in a linear baroclinic model with the observed zonal mean basic state. Furthermore, both theoretical and modelling analyses demonstrated that the fact that zonal wave patterns are preferred in the NH stratosphere may be partly attributable to the vertical curvature of the stratospheric zonal mean basic state.

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Interdecadal Variations of the East Asian Winter Monsoon and Their Association with Quasi-Stationary Planetary Wave Activity

Cited by 182 publications

References 31 publications

Trends in Precipitation Extremes over Southeast Asia

Trends in Precipitation Extremes over Southeast Asia

Winter climate changes over East Asian region under RCP scenarios using East Asian winter monsoon indices

Contrasting meridional structures of stratospheric and tropospheric planetary wave variability in the Northern Hemisphere

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