The Growth and Triggering Mechanisms of the PNA: A MJO-PNA Coherence

Mori, Masato; Watanabe, Masahiro

doi:10.2151/jmsj.86.213

Cited by 170 publications

(159 citation statements)

References 43 publications

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“…These results demonstrate that the wave train (A1-C1-A2 in Fig. 3c) along the Asian jet is excited by the divergent wind anomaly associated with MJO convection located over Indian Ocean, which is in agreement with the findings by Mori and Watanabe (2008). They showed the excitation of a wave train by divergent winds associated with the MJO along the Asian jet and its development into the PNA (Pacific North American) pattern.…”

Section: Evolution Of Extratropical Circulation Anomalysupporting

confidence: 90%

“…The MJO extratropical circulation appears to be a mixture of the direct Rossby wave response to tropical heating and interaction between the divergent and rotational flow embedded in Rossby wave-like disturbances (e.g., Hsu 1996). The MJO-related circulation anomalies can extract energy from the mean flow by barotropic conversion (e.g., Hsu 1996;Matthews et al 2004;Mori and Watanabe 2008).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Evolution Of Extratropical Circulation Anomalysupporting

confidence: 90%

Section: Introductionmentioning

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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“…To first order, this PNA-like response can be predicted with simple linearized barotropic models forced with upper tropospheric divergence in the tropical Pacific (e.g., Branstator 1985;Hoskins and Karoly 1981;Seo and Son 2012). Consistent with this basic mechanism, observational studies have found that the positive (negative) phase of the PNA is more common during and after MJO-related enhanced (suppressed) convection over the western and central tropical Pacific (e.g., Ferranti et al 1990;Higgins and Mo 1997;Johnson and Feldstein 2010;Knutson and Weickmann 1987;Mori and Watanabe 2008). However, non-barotropic mechanisms are also needed to explain the timing, location and amplitude of the PNA response (e.g., Higgins and Mo 1997;Hsu 1996;Trenberth et al 1998).…”

Section: Introductionmentioning

confidence: 81%

“…The mechanisms leading to these relationships have been studied extensively on seasonal timescales (see Trenberth et al 1998 for a review) as well as on intraseasonal timescales, such as those associated with the MJO (e.g., Ferranti et al 1990;Higgins and Mo 1997;Johnson and Feldstein 2010;Matthews et al 2004;Mori and Watanabe 2008;Seo and Son 2012). At both of these timescales, increased (decreased) convection over the equatorial central Pacific is associated, to first order, with an enhancement (reduction) in upper level divergence, an extension (retraction) of the Pacific subtropical jet, and associated modification of midlatitude storm tracks.…”

Section: Introductionmentioning

confidence: 99%

The impact of the MJO on clusters of wintertime circulation anomalies over the North American region

Riddle¹,

Stoner²,

et al. 2012

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Recent studies have shown that the MaddenJulian Oscillation (MJO) impacts the leading modes of intraseasonal variability in the northern hemisphere extratropics, providing a possible source of predictive skill over North America at intraseasonal timescales. We find that a k-means cluster analysis of mid-level geopotential height anomalies over the North American region identifies several wintertime cluster patterns whose probabilities are strongly modulated during and after MJO events, particularly during certain phases of the El Niño-Southern Oscillation (ENSO). We use a simple new optimization method for determining the number of clusters, k, and show that it results in a set of clusters which are robust to changes in the domain or time period examined. Several of the resulting cluster patterns resemble linear combinations of the Arctic Oscillation (AO) and the Pacific/North American (PNA) teleconnection pattern, but show even stronger responses to the MJO and ENSO than clusters based on the AO and PNA alone. A cluster resembling the positive (negative) PNA has elevated probabilities approximately 8-14 days following phase 6 (phase 3) of the MJO, while a negative AO-like cluster has elevated probabilities 10-20 days following phase 7 of the MJO. The observed relationships are relatively well reproduced in the 11-year daily reforecast dataset from the National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). This study statistically links MJO activity in the tropics to common intraseasonal circulation anomalies over the North American sector, establishing a framework that may be useful for improving extended range forecasts over this region.Keywords The Madden-Julian Oscillation (MJO) Á Tropical-extratropical connections Á Intraseasonal climate variability Á Extended range prediction Á Cluster analysis Á Model hindcasts Á The Arctic Oscillation (AO) Á

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“…Thus, the typical value of E k used in our study is 2.3e-05 s −1 , which corresponds to BL damping time scale of approximately 0.5 day. This value is as the same as that used in Mori and Watanabe (2008). This value is also used to compensate the neglected effects of complex nonlinear processes.…”

Section: The Sensitivity Of Solutions To Model Parametersmentioning

confidence: 99%

A general theoretical framework for understanding essential dynamics of Madden–Julian oscillation

Wang

Chen

2016

Clim Dyn

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The Growth and Triggering Mechanisms of the PNA: A MJO-PNA Coherence

Cited by 170 publications

References 43 publications

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

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

The impact of the MJO on clusters of wintertime circulation anomalies over the North American region

A general theoretical framework for understanding essential dynamics of Madden–Julian oscillation

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