Super East Asian monsoon Mei-yu in June and July 2020 tied to dissimilar-shifting upper-level westerlies

Liu, Caihong; Hu, Chundi; Yang, Song; Li, Lin; Wu, Zeming

doi:10.1016/j.atmosres.2022.106213

Cited by 10 publications

(10 citation statements)

References 65 publications

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“…Figure 2 displays monthly SST, 850‐hPa wind, and precipitation anomalies for June to September 2020 over the Indo‐Pacific region. The pattern of SST anomalies in the equatorial Pacific is reminiscent of weak La Niña‐like conditions as indicated by earlier studies (e.g., Chen et al ., 2022; Liu et al ., 2022). These negative SST anomalies are extended westward till the dateline from the South American coast during August and September 2020, while the westward extension is restricted to 140° W in June and July.…”

Section: Resultsmentioning

confidence: 99%

“…Liu et al . (2022) suggested that the East Asian westerly jet shifted southward due to a robust PJ mode in July 2020, whereas in June 2020 the East Asian westerly jet displaced northward in response to a high‐latitude Rossby wavetrain that originated from the western North Atlantic. Chen et al .…”

Section: Resultsmentioning

confidence: 99%

“…Over the East Asian region, the warm moist westerly jet conjunctively forms a zonally elongated quasi-stationary Meiyu-Baiu rain band from Central China to Japan (e.g., Sampe & Xie, 2010;Zhou & Yu, 2005), which is apparent in July 2020 (Figure 2f). Liu et al (2022) suggested that the East Asian westerly jet shifted southward due to a robust PJ mode in July 2020, whereas in June 2020 the East Asian westerly jet displaced northward in response to a high-latitude Rossby wavetrain that originated from the western North Atlantic. Chen et al (2022) concluded that during July the Meiyu-Baiu rainfall is extensively positive due to the stronger meridional convergence and stronger mid-upper tropospheric westerly jets associated with the barotropic circulation anomalies.…”

Section: 12mentioning

confidence: 99%

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Unusual subseasonal variability of Indian summer monsoon rainfall in 2020

Darshana,

Chowdary,

Parekh

et al. 2024

Quart J Royal Meteoro Soc

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Above‐normal all‐India summer monsoon (ISM) rainfall was received in 2020 with 109% of its long‐period average. According to the India Meteorological Department (IMD), ISM 2020 experienced robust month‐to‐month rainfall variations; in particular, the peak monsoon month of July 2020 witnessed deficit rainfall. The present study investigated the possible mechanisms that are responsible for the July 2020 deficit rainfall. Analysis revealed that the strong low‐level moisture divergence caused by the westward‐propagating atmospheric Rossby wave, induced by suppressed western North Pacific (WNP) convection, is primarily responsible for the July rainfall deficit. The WNP suppressed convection is linked to anomalous low‐level anticyclonic circulation. It is noted that the intense WNP anticyclone is maintained by the tropical Indian Ocean (TIO) warming‐induced atmospheric Kelvin waves and strong low‐level convergence over the Meiyu‐Baiu rainband. Unlike July, the strength of the WNP anticyclone and TIO warming are weaker in June and August. In addition to the observational analysis, the skill of the Climate Forecast System version‐2 (CFSv2) model in predicting the July rainfall at a lead of about two months is examined. Strong positive rainfall anomalies over India are predicted by the model in July, which is in contrast to the observations. Despite predicting the TIO warming, the model failed to capture the westward extension of the WNP anticyclone, which impacted the July rainfall prediction. To understand the importance of the WNP anticyclone on ISM rainfall, a CFSv2 sensitivity experiment is carried out by imposing strong negative sea surface temperature (SST) anomalies over the WNP region to excite the anticyclone. Both the westward extension of the WNP anticyclone and suppressed rainfall over the core monsoon region in July are captured by the model when low‐level circulation is imposed. The model sensitivity experiment strongly supports the role of the WNP anticyclone and its westward extension in inducing reduced rainfall in July 2020 over the monsoon trough region.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: 12mentioning

confidence: 99%

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Unusual subseasonal variability of Indian summer monsoon rainfall in 2020

Darshana,

Chowdary,

Parekh

et al. 2024

Quart J Royal Meteoro Soc

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“…The intense and persistent Meiyu precipitation in the mid‐lower Yangzte River basin in the summer of 2020 is a consequence of the negative phase of the PJ pattern, which is induced by the warm TIO SST anomalies (Takaya et al, 2020; Ding et al, 2021). The persistence of the PJ pattern substantially contributes to the Meiyu precipitation in July 2020 (Liu et al, 2022). The current study merely demonstrated the effects of the interdecadal variations of the PJ pattern on the East Asian summer precipitation.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

The role of SST forcing in the interdecadal variations of the Pacific‐Japan pattern in the late 1990s

Yan

et al. 2022

Intl Journal of Climatology

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The Pacific-Japan (PJ) pattern is the dominant teleconnection over East Asia, closely related to the summer precipitation on various time scales. However, studies on the connection between the interdecadal variations of the PJ pattern and sea surface temperature (SST) forcing are still limited. This study indicates that the relationship between the PJ pattern and ENSO presents a pronounced interdecadal change around 1997/1998. The PJ pattern shows a baroclinic structure over the northwest Pacific and a barotropic structure near Japan during 1979-1997, while its baroclinic structure in the tropics weakens remarkably during 1998-2021, with a southward shift of its midlatitude barotropic structure. As a result, the connection between the PJ pattern and summer precipitation over East Asia exhibits an interdecadal transition in the late 1990s.

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“…Meanwhile, sub-seasonal variability of the WNPSH is also influenced by the intra-seasonal processes over the Indian Ocean (e.g., Kim et al, 2021;Wang et al, 2021d;Zhang et al, 2021b;Liu et al, 2022;Wang et al, 2022). Zhang et al (2021b) and Liu et al (2021) argued that under the IOBW background the intense and long-lasting quasi-stationary Madden-Julian Oscillation in June and July (JJ) 2020 over the tropical Indian Ocean helped strengthen the low-level anticyclone over the WNP.…”

Section: The Indian Ocean and The Wnpshmentioning

confidence: 99%

Extreme Mei-yu in 2020: Characteristics, causes, predictability and perspectives

Liu,

Hu,

Yang

et al. 2023

Earth-Science Reviews

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Super East Asian monsoon Mei-yu in June and July 2020 tied to dissimilar-shifting upper-level westerlies

Cited by 10 publications

References 65 publications

Unusual subseasonal variability of Indian summer monsoon rainfall in 2020

Unusual subseasonal variability of Indian summer monsoon rainfall in 2020

The role of SST forcing in the interdecadal variations of the Pacific‐Japan pattern in the late 1990s

Extreme Mei-yu in 2020: Characteristics, causes, predictability and perspectives

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