Predictability of Wintertime Stratospheric Circulation Examined Using a Nonstationary Fluctuation–Dissipation Relation

Inatsu, Masaru; Nakano, Nobuo; Kusuoka, Shigeo; Mukougawa, Hitoshi

doi:10.1175/jas-d-14-0088.1

Cited by 9 publications

(12 citation statements)

References 40 publications

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“…Resultantly, we have ten SSW events in the analysis period from 2001/02 to 2005/06 boreal winters, as shown later in the second column of Table 1 Note that the number of defined SSW events during a period from 2001/02 to 2005/06 winter is ten, which is 2.5 times larger than that of major SSW events based on the definition of Charlton and Polvani (2007) as shown in Fig. 10a of Inatsu et al (2015). This is because our definition of SSW events is lenient in comparison with that of major SSW events used in those studies.…”

Section: Features Of Stratospheric Circulationsmentioning

confidence: 85%

Predictability Changes of Stratospheric Circulations in Northern Hemisphere Winter

Ichimaru

Noguchi

Hirooka

et al. 2016

Journal of the Meteorological Society of Japan

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Practical predictability of the stratospheric circulation in the boreal winters during the period [2001][2002][2003][2004][2005][2006] has been examined using the archive of 1-month ensemble forecast datasets provided by the Japan Meteorological Agency. To investigate the predictability limit, two measures of the Root-Mean-Square Error (RMSE) and Anomaly Correlation (AC) have been used for the 10-hPa geopotential height field. In the winter stratosphere, an intermittent character of planetary wave activity causes two specific periods of the stratospheric circulation, i.e., an undisturbed phase with inactive planetary waves and a disturbed phase with active ones. Therefore, the predictability needs to be evaluated taking account of this feature. On the basis of careful consideration, the mean predictable period can be estimated to about 10 days during the disturbed phase; it is longer than the tropospheric predictable period of about 7 days. However, it exhibits large variability because of different growth rates of forecast errors caused by contributions of both wave and zonal-mean fields. During the undisturbed phase, the predictable period based on the AC is almost the same as that of the disturbed phase, although the predictable period based on the RMSE is extremely long, since the RMSE predictability is measured against the climatological standard deviation affected by disturbed phases. Therefore, the horizontal pattern of the stratospheric circulation is less predictable even though the forecast error is quite small.

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Section: Features Of Stratospheric Circulationsmentioning

confidence: 85%

Predictability Changes of Stratospheric Circulations in Northern Hemisphere Winter

Ichimaru

Noguchi

Hirooka

et al. 2016

Journal of the Meteorological Society of Japan

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“…SSWs themselves, however, remain hard to predict (e.g., Mukougawa and Hirooka 2004;Simmons et al 2005;Inatsu et al 2015). Furthermore, the generation of SSWs is still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Sudden Stratospheric Warmings and Anomalous Upward Wave Activity Flux

Birner

Albers

2017

SOLA

129

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Abrupt breakdowns of the polar winter stratospheric circulation such as sudden stratospheric warmings (SSWs) are a manifestation of strong two-way interactions between upward propagating planetary waves and the mean flow. The importance of sufficient upward wave activity fluxes from the troposphere and the preceding state of the stratospheric circulation in forcing SSWlike events have long been recognized. Past research based on idealized numerical simulations has suggested that the state of the stratosphere may be more important in generating extreme stratospheric events than anomalous upward wave fluxes from the troposphere. Other studies have emphasized the role of tropospheric precursor events. Here reanalysis data are used to define events of extreme stratospheric mean flow deceleration (SSWs being a subset) and events of extreme lower tropospheric upward planetary wave activity flux. While the wave fluxes leading to SSWlike events ultimately originate near the surface, the anomalous upward wave activity fluxes associated with these events primarily occur within the stratosphere. The crucial dynamics for forcing SSW-like events appear to take place in the communication layer just above the tropopause. Anomalous upward wave fluxes from the lower troposphere may play a role for some events, but seem less important for the majority of them.(Citation: Birner, T., and J. R. Albers, 2017: Sudden stratospheric warmings and anomalous upward wave activity flux. SOLA, 13A, 8−12,

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“…We thus have 4+m control parameters: m, h, ρ, µ * , and δ 1 , δ 2 , · · · , δ m for defining the multi-valued map F. Among them, we set the dimension of the 'phase space' m = 2 throughout the paper, following earlier studies [16,17,13,12].…”

Section: 2mentioning

confidence: 99%

Topological Computation Analysis of Meteorological Time-Series Data

Morita¹,

Inatsu²,

Kokubu³

2019

SIAM J. Appl. Dyn. Syst.

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A topological computation method (called the MGSTD method) is applied to noisy time-series data obtained from meteorological measurement. This method is based on the idea of the Morse decomposition, which is a decomposition of the dynamics into invariant sets, called the Morse sets, and their gradient-like connections. A Morse decomposition of a dissipative dynamical system can be obtained by dividing the phase space into grids and constructing a combinatorial multivalued map over the grids [4,6]. In the case of time-series data generated by a dynamical system, a combinatorial multi-valued map over the grids can be similarly constructed. However, time-series data obtained from real measurements (e.g., meteorological data) are often highly stochastic due to the presence of noise. A multi-valued map is then determined statistically by preferable transitions between the grids. We consider time-series data taken from the first two principal components of the pressure patterns in the troposphere and the stratosphere in the northern hemisphere, measured over 31 years, 90 days in each year × every 6 hours per day. The application of the MGSTD method to the troposphere data yields some particular transitions between the Morse sets, corresponding to specific motions in the phase space spanned by the principal components. The motions detected by our analysis are consistent with changes between characteristic pressure patterns that have been previously recognized in meteorological studies. A similar result is also obtained with the stratosphere data.

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Predictability of Wintertime Stratospheric Circulation Examined Using a Nonstationary Fluctuation–Dissipation Relation

Cited by 9 publications

References 40 publications

Predictability Changes of Stratospheric Circulations in Northern Hemisphere Winter

Predictability Changes of Stratospheric Circulations in Northern Hemisphere Winter

Sudden Stratospheric Warmings and Anomalous Upward Wave Activity Flux

Topological Computation Analysis of Meteorological Time-Series Data

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