An Aerological Study on the Pre-summer Rainy Season in Japan

Matsumoto, Seiichi; Itoo, H.; Arakawa, Akio

doi:10.2151/jmsj1923.32.4_85

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…However, further studies are necessary, in order to clarify the problems relating to the subject. There are many studies on the Bai-u pheno menon, a large number of which particularly focus on the divisions within the Bai-u season (MATSUMOTO et al, 1954;YOSHINO,1965;MIZUKOSHI, 1986). Before going on to comparisons, it should be noted that, where the criteria for the division of the Bai-u season, considered space-scale and meteorological elements are concerned, the pres ent study differs from other studies on a similar subject.…”

Section: Periodicities In the Bai-u Seasonmentioning

confidence: 99%

Secular Changes of the Bai-u Season in Japan

Murata

1987

Geogr. Rev. Jpn, Ser B

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The Bai-u season between the beginning of the eighteenth century and 1895 was reconstructed with the aid of weather records entered in old diaries. Long-term tendencies and periodicities of the Bai-u season were investigated by linking the reconstructed data to that of an instrumentally observed time.Generally speaking, with regard to its beginning, end and duration, there are no significant differences between the Bai-u season in the historical time and in the instrumental time.Thus, the implication is that the characteristics of the Bai-u season in the Little Ice Age were the same as those in the post-Little Ice Age. The duration of the Bai-u season revealed a strong positive correlation with the end of the Bai-u season in both the historical and the instrumental time. The time series of the end and the duration of the Bai-u season indicated a longer cycle of around sixty years. It was also observed that three great famines were associated with late endings of the Bai-u season.In particular, the Tohoku District was adversely affected by cool summers during the years when the end of the Bai-u season was late.I.

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Section: Periodicities In the Bai-u Seasonmentioning

confidence: 99%

Secular Changes of the Bai-u Season in Japan

Murata

1987

Geogr. Rev. Jpn, Ser B

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“…A similar wet season in southern China is associated with distur-bances in the form of velocity convergences in the monsoonal southwesterly currents 12 ). It has been suggested that the Baiu rains are heavier over Japan when a single jet prevails and less when there is a double jet 13 . In other words, when the confluence of the summer East-Asian jets occurs to the west of Japan, usually over the margins of the continent, Baiu rains are abnormally heavy, and when the confluence occurs farther to the east, over the western Pacific, the rains are less abundant.…”

Section: Figmentioning

confidence: 99%

Climate as related to the Jet Stream in the Orient

Trewartha¹

1958

erd

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Southern Hemisphere baroclinic activity in seasonal forecasts

Trentini,

Calmanti,

Dell’Aquila

et al. 2024

Bull. of Atmos. Sci.& Technol.

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Accurate prediction of mid-latitude baroclinic activity is extremely relevant for understanding global climate dynamics and improving long-term weather forecasts. However, current seasonal forecast models struggle to accurately represent the variability of baroclinic activity in the Southern Hemisphere, which may affect their reliability and usefulness. Baroclinic instability in the mid-latitudes is a significant component of the climate system, as it is associated with the meridional transport of a large amount of energy and momentum. Therefore, the ability of the models to correctly predict the properties of the atmospheric circulation in this latitudinal region is a very important requirement. The aim of this study is to estimate the energy of atmospheric phenomena typical of the mid-latitudes, such as baroclinic perturbations, and to understand how seasonal forecasts can be practically used to assess the energy transfer in the atmosphere. We compare the Southern Hemisphere mid-latitude winter variability of the seasonal forecasts of the ECMWF, DWD and Météo France forecasting systems with the ERA5 reanalysis. The analysis is performed by computing the Hayashi spectra of the 500-hPa geopotential height field. Both the reanalysis and the seasonal forecast show a series of peaks in the spectral region of eastward-travelling waves, which corresponds to the high frequency and high wavenumber domain. We quantify the amount of energy released from the atmosphere by calculating the Baroclinic Amplitude Index. The results suggest that seasonal forecasts may not accurately capture the variability of geopotential height power spectra in the Southern Hemisphere, which poses a challenge in correctly distributing the energy over spatial and temporal dimensions. This study will show that this problem is particularly pronounced for wavenumber 4 over a period of 8 days. This misrepresentation likely contributes to the uncertainties in precipitation forecasting, with discrepancies exacerbated by a suboptimal description of baroclinic instability and dynamical components in the models. Our findings highlight the need for an improved representation of baroclinic processes in seasonal forecast models, which could lead to substantial advancements in long-term weather prediction capabilities and in a more complete understanding of climate dynamics.

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An Aerological Study on the Pre-summer Rainy Season in Japan

Cited by 4 publications

References 18 publications

Secular Changes of the Bai-u Season in Japan

Secular Changes of the Bai-u Season in Japan

Climate as related to the Jet Stream in the Orient

Southern Hemisphere baroclinic activity in seasonal forecasts

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