The 1985/86 Intraseasonal Oscillation and the Role of the Extratropics

Hsu, Huang‐Hsiung; Hoskins, Brian J.; Jin, Fei‐Fei

doi:10.1175/1520-0469(1990)047<0823:tioatr>2.0.co;2

Cited by 165 publications

(119 citation statements)

References 0 publications

Supporting

Mentioning

112

Contrasting

Order By: Relevance

“…Upper-level potential vorticity anomalies are known to propagate from the mid-latitudes into the tropics; this propagation is associated with NW-SE tilting troughs (64). They are accompanied by cold surges and can cause episodes of intense tropical convection that seem to be related to the intraseasonal oscillation in the tropics (65,66).…”

Section: Markov Chains Transition Matricesmentioning

confidence: 97%

“Waves” vs. “particles” in the atmosphere's phase space: A pathway to long-range forecasting?

Ghil

Robertson

2002

Proc. Natl. Acad. Sci. U.S.A.

168

169

View full text Add to dashboard Cite

Thirty years ago, E. N. Lorenz provided some approximate limits to atmospheric predictability. The details-in space and time-of atmospheric flow fields are lost after about 10 days. Certain gross flow features recur, however, after times of the order of 10 -50 days, giving hope for their prediction. Over the last two decades, numerous attempts have been made to predict these recurrent features. The attempts have involved, on the one hand, systematic improvements in numerical weather prediction by increasing the spatial resolution and physical faithfulness in the detailed models used for this prediction. On the other hand, theoretical attempts motivated by the same goal have involved the study of the large-scale atmospheric motions' phase space and the inhomogeneities therein. These ''coarse-graining'' studies have addressed observed as well as simulated atmospheric data sets. Two distinct approaches have been used in these studies: the episodic or intermittent and the oscillatory or periodic. The intermittency approach describes multiple-flow (or weather) regimes, their persistence and recurrence, and the Markov chain of transitions among them. The periodicity approach studies intraseasonal oscillations, with periods of 15-70 days, and their predictability. We review these two approaches, ''particles'' vs. ''waves,'' in the quantum physics analogy alluded to in the title of this article, discuss their complementarity, and outline unsolved problems.

show abstract

Section: Markov Chains Transition Matricesmentioning

confidence: 97%

“Waves” vs. “particles” in the atmosphere's phase space: A pathway to long-range forecasting?

Ghil

Robertson

2002

Proc. Natl. Acad. Sci. U.S.A.

168

169

View full text Add to dashboard Cite

show abstract

“…The triggering effect of cold-dry high PV air on the convection when it penetrated southward to warm moist surface has been reported in previous studies [e.g., Hsu et al, 1990]. In addition to the close correspondence with the PV anomaly, the specific humidity plot (Figure 2d) also reveals two northward-propagating events from 20°N to 35°N, which were associated with the northward-propagating convective perturbation seen in Figure 2a.…”

Section: Extreme Rainfall and Anomalous Large-scale Circulationmentioning

confidence: 99%

Roles of European blocking and tropical-extratropical interaction in the 2010 Pakistan flooding

Chen¹,

Hsu

Lin

et al. 2011

Geophys. Res. Lett.

Self Cite

147

134

View full text Add to dashboard Cite

A sequence of monsoon surges struck Pakistan and Northwestern India during late July‐early August 2010. The unusually heavy monsoon rainfall resulted in record‐breaking floods, which affected 20 million people with a death toll of near 3000. Simultaneously, a long‐lived blocking high appeared over Europe and Russia in middle June and persisted for nearly two months. Extreme flooding occurred when the southward penetration of extratropical potential vorticity in the deep trough east of the European blocking and the tropical monsoon surges arrived concurrently in Pakistan. This study demonstrates that the interaction between the tropical monsoon surges and the extratropical disturbances downstream of the European blocking was the key factor leading to the severe flooding in Pakistan. The 2010 La Niña condition contributed indirectly to the flooding by inducing a low‐level easterly anomaly in South and Southeast Asia, which weakened eastward moisture transport and helped enhance moisture transport (convergence) to (in) the Northern Arabian Sea and Pakistan.

show abstract

“…This type of case is mostly observed over the central Pacific and the Atlantic (Matthews and Kiladis, 1999;Lin et al, 2007) because the westerlies in these regions allow the Rossby waves to propagate into the deep Tropics. In addition, Hsu et al (1990) provided evidence that a Rossby wave train could propagate into the Indian Ocean and play a role in initiating a particular MJO event on 3 January 1986.…”

Section: Introductionmentioning

confidence: 63%

“…The existing hypotheses about MJO initiation can be roughly grouped into five categories: local discharge-recharge processes, extratropical influences, upstream effects of circumnavigating waves, stochastic forcing, and other factors such as atmospheric boundary-layer convergence and moisture, oceanic forcing, and midtropospheric thermodynamical forcing (Kemball-Cook and Weare, 2001;Matthews, 2008;Ray et al, 2009), among which the extratropical processes are regarded as important ingredients (Liebmann and Hartmann, 1984;Lau and Peng, 1987;Hsu et al, 1990;Lau et al, 1994;Matthews et al, 1996;Matthews and Kiladis, 1999;Lin et al, 2007;Matthews, 2008). Recently, some numerical studies have shown that the realistic MJO cannot be generated without disturbances from lateral/extratropical boundaries (Ray et al, 2009;Ray and Zhang, 2010), further suggesting the importance of the extratropical influences in the initiation of the MJO.…”

Section: Introductionmentioning

confidence: 78%

Observed triggering of tropical convection by a cold surge: implications for MJO initiation

Wang

Kodera

Chen

2012

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

The extratropical influence is an important mechanism in the initiation of the Madden-Julian Oscillation (MJO). Based on analyses of several datasets, this article demonstrates that the MJO case initiated in late January 2008 was strengthened by a preceding cold surge over West Asia when the MJO was at its initiation phase. The cold surge-related northerlies propagated southward along the east coast of Africa. The associated convergence on the edge of the surge enhanced ascending motion in the tropical western Indian Ocean and led to the onset of deep convection to the north of Madagascar. This process helped to amplify the MJO convection rapidly, as shown in the development of the moist static energy anomalies. In this way, the cold surge affected the behaviour of the MJO and modified the timing of its initiation to some extent. These results support previous studies that extratropical factors are important for the initiation of the MJO, and suggest that the subtropical cold surges are likely to strengthen and accelerate the build-up of deep MJO convection at the MJO initiation phase.

show abstract

The 1985/86 Intraseasonal Oscillation and the Role of the Extratropics

Cited by 165 publications

References 0 publications

“Waves” vs. “particles” in the atmosphere's phase space: A pathway to long-range forecasting?

“Waves” vs. “particles” in the atmosphere's phase space: A pathway to long-range forecasting?

Roles of European blocking and tropical-extratropical interaction in the 2010 Pakistan flooding

Observed triggering of tropical convection by a cold surge: implications for MJO initiation

Contact Info

Product

Resources

About