Interannual and Decadal Modulations Recently Observed in the Pacific Storm Track Activity and East Asian Winter Monsoon

Nakamura, Hisashi; Izumi, Takeshi; Sampe, Takeaki

doi:10.1175/1520-0442(2002)015<1855:iadmro>2.0.co;2

Cited by 194 publications

(225 citation statements)

References 34 publications

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“…It is important to consider whether the EAWM influences rainfall variation over NEA. The regression pattern of TASMI with respect to geopotential height at 925 hPa (figure not shown) indicates that variations in TASM are linked to the strength of the Aleutian low, which is one of important reflections of EAWM variations (Nakamura et al, 2002;Gao, 2007). The correlation coefficient between TASM and the Aleutian low index (defined as the areal mean SLP over the domain 40°-60°N, 150°E-140°W) is 0.42, significant at the 0.01 level.…”

Section: Discussionmentioning

confidence: 98%

A possible cause of decreasing summer rainfall in northeast Australia

Li¹,

Feng²,

Li³

2011

Intl Journal of Climatology

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ABSTRACT:The NCEP/NCAR reanalysis and precipitation data from the Australian Bureau of Meteorology are used to analyse variability in rainfall during the austral summer (December-March, DJFM) in northeast Australia (NEA). NEA rainfall shows a marked decrease over the past 50 years, mainly in the austral summer. Our analysis reveals that the summer rainfall decrease in NEA is generally an interdecadal phenomenon. The declining trend has an imprint in the tropical Australian summer monsoon (TASM). Not only does TASM have a phase-to-phase influence on NEA summer rainfall at the interannual scale, it is also closely linked with interdecadal variation in NEA summer rainfall. Thus, the decrease in NEA at the interdecadal scale could be attributed to corresponding variation in TASM. Moreover, the coupled linkage between TASM and NEA summer rainfall appears to be largely independent of El Niño-Southern Oscillation. One possible reason for the interdecadal weakening trend in TASM is a sustained interdecadal warming trend in sea surface temperature (SST) over the Wharton Basin (100°-130°E, 20°-5°S). When the Wharton Basin is in a cold state, anomalous westerlies occur in the lower troposphere in the TASM region, and cyclonic circulation anomalies and rising flows occur in the low and middle troposphere over NEA, which are associated with a strong TASM situation, consequently favouring enhanced rainfall over NEA; the opposite occurs in the case of a warm Wharton Basin. SST over the Wharton Basin has shown a continuous warming trend over the past 60 years, contributing to the weakening of TASM and, consequently, a decrease in NEA summer rainfall.

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Section: Discussionmentioning

confidence: 98%

A possible cause of decreasing summer rainfall in northeast Australia

Li¹,

Feng²,

Li³

2011

Intl Journal of Climatology

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“…As the wintertime strong westerlies weaken, the synoptic eddy activity in the low-level tends to increase over the North Pacific (e.g., Nakamura 1992;Chang 2001;Nakamura et al 2002). Chang (2001) and Nakamura et al (2002) showed that the amplitude of the eddies under the weakend jet increases through strengthened vertical coupling due to an enhanced energy conversion from the mean-flow available potential energy into the eddy kinetic energy for growth. Hence, it is suggested that the convective activity increases in association with the enhancement of synoptic-eddy activity under the suppressed upper-level westerly in the EANP region.…”

Section: Summary and Discussionmentioning

confidence: 99%

The Madden-Julian Oscillation and Extratropical Teleconnection over East Asia during the Northern Winter in IPCC AR4 Climate Models

Takahashi

Yoneyama

Sato

et al. 2012

Journal of the Meteorological Society of Japan

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The reproducibility of the extratropical teleconnection in East Asia associated with the Madden-Julian Oscillation (MJO) during the boreal winter is evaluated in the 20 th century experiment (20C3M) outputs from 16 global climate models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). It is revealed that five of the models (BEST models) realistically simulate the MJOextratropical convection teleconnection. These models successfully represent the MJO convective signals better than the other models. Through analysis of the wave activity flux and Rossby wave source (RWS), the upper-level extratropical wave train induced by MJO convection is demonstrated to propagate northeastward along the Asian jet with its reinforcement, which eventually a¤ects the convective variability in East Asia. The BEST models pronouncedly reproduce the extratropical wave train and RWS. However, the other models produce unrealisCorresponding author: Chiharu Takahashi, Research Institute for Global Change, Japan Agency for MarineEarth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan. E-mail: takachi@jamstec.go.jp 6 2012, Meteorological Society of Japan tic or no extratropical wave trains due to unrealistically produced RWSs, although all models realistically exhibit the climatological absolute vorticity over the Asian jet as a waveguide. Furthermore, only the BEST models reproduce the low-level moisture transport with southerlies from the tropics into East Asia, which are associated with realistically reproduced anticyclonic circulation over the North Pacific, that is largely formed as a Rossbywave response to the cooling anomaly with meaningful suppressed convection over tropical western and central Pacific. In summary, correctly simulating the intensity of the MJO convection and its eastward propagation into the Pacific is necessary in order to predict the wintertime climate variability over East Asia.

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“…This state holds in midwinter and is often found in early and late winter, anti-correlated with seasonal variations in the storm track activity in the western North Pacific (Nakamura 1992). Moreover, Nakamura et al (2002) suggested that the intensity of storm activity is weak during winters with a strong Aleutian low pressure, and strong when the Aleutian 4 low pressure is weak. This seasonal and interannual variability of storm activity has been comprehensively studied, and is well understood (Nakamura et al 2004).…”

Section: Introductionmentioning

confidence: 93%

Wintertime extratropical cyclone frequency around Japan

Inatsu

Terakura

2011

Clim Dyn

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Data analysis and regional atmospheric model (RAM) experiments revealed key factors in the control of wintertime cyclone passage routes from Northeast Asia to the western North Pacific. The cyclone routes were independent of the global flow pattern in the interannual variability, while cyclone growth closely agreed with linear baroclinic theory. The RAM experiments with a different lateral boundary condition composed of a combination of monthly mean and transient components also showed that the upstream eddies are important for the track route, but the background states are not. Additionally, the RAM experiments showed that the mean flow controlled the growth rate of cyclones.

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Interannual and Decadal Modulations Recently Observed in the Pacific Storm Track Activity and East Asian Winter Monsoon

Cited by 194 publications

References 34 publications

A possible cause of decreasing summer rainfall in northeast Australia

A possible cause of decreasing summer rainfall in northeast Australia

The Madden-Julian Oscillation and Extratropical Teleconnection over East Asia during the Northern Winter in IPCC AR4 Climate Models

Wintertime extratropical cyclone frequency around Japan

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