Reduced Probability of 2020 June–July Persistent Heavy Mei-yu Rainfall Event in the Middle to Lower Reaches of the Yangtze River Basin under Anthropogenic Forcing

Tang, Haosu; Wang, Ziyue; Tang, Bin; Ma, Yunxiang; Pei, Lin; Tian, F.; Wang, Jun; Nanding, Nergui; Sparrow, Sarah; Tett, Simon F. B.; Dong, Buwen; Lott, Fraser C.

doi:10.1175/bams-d-21-0167.1

Cited by 13 publications

(9 citation statements)

References 9 publications

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“…In 2020, a large amount of rain fell over East Asia during the Meiyu-Baiu season from June to July, inducing many recordbreaking heavy rainfalls and great damage due to the floods and landslides (e.g., JMA 2020;Araki et al, 2021;Qiao et al, 2021). Previous studies indicated that the cause of this long-persisting Meiyu-Baiu season in 2020 combined the influences of multiple sources from the tropics, mid-and high latitudes, such as the Indian Ocean basin warming that can further be related to the 2019 super Indian Ocean Dipole (e.g., Takaya et al, 2020;Cai et al, 2022), teleconnections that related to the North Atlantic Oscillation and the Madden-Julian Oscillation (e.g., Liu et al, 2020;Horinouchi et al, 2021;Zhang et al, 2021), and the Arctic and global warming (e.g., Chen M et al, 2021;Nakamura and Sato 2022;Tang et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Impacts of moisture supply from the subtropical western Pacific on the subtropical high and the atmospheric river during the heavy rain of 2020 in Japan

Zhao

Manda²,

Guo³

et al. 2022

Front. Earth Sci.

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Our recent study suggested that moisture from the subtropical Western Pacific (WP) contributed the most to an atmospheric river (AR) event and the related heavy rainfall during the heavy rain of 2020 in Japan based on a Lagrangian approach. However, the actual role of moisture from the subtropical WP region in the AR and heavy rain formations remains unclear. To evaluate that, we conducted a set of numerical sensitivity experiments by adjusting the surface moisture supply over the subtropical WP region with factors of 0%, 50%, and 200%. The sensitivity experiments suggest that the reduced surface evaporation over the subtropical WP suppressed the local convective activity and decreased moisture content in the whole troposphere, leading to shallow and weak positive geopotential height anomalies. Although the slightly strengthened WP subtropical High (WPSH) and related anomalous anticyclonic circulation enhanced the southwesterly wind, convective activities along the Meiyu-Baiu front were still weakened due to the largely reduced moisture supply, resulting in another anomalous anticyclonic circulation over Japan but had much stronger and deeper structures. These two anomalous circulations and the reduced moisture modulated the AR over Japan, which eventually caused the weakened rainfalls and the northward migration of the rainband. By contrast, larger surface evaporation enhanced the local convective activities and weakened the dominant WPSH, resulting in the weakening and the southward migration of the AR. Overall, this study confirmed the large contributions of moisture supply from the subtropical WP region to the AR and related precipitation over Japan during the record-breaking Meiyu-Baiu season in 2020 via both dynamic and thermodynamic influences. In addition, it reveals that, although larger evaporation over the WP region would increase the total rainfalls but would not have led to more several rainfalls over certain regions, such as the relatively small Kyushu Island.

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Section: Introductionmentioning

confidence: 99%

Impacts of moisture supply from the subtropical western Pacific on the subtropical high and the atmospheric river during the heavy rain of 2020 in Japan

Zhao

Manda²,

Guo³

et al. 2022

Front. Earth Sci.

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“…On the basis of different event definitions, models [e.g., HadGEM3-GA6 and Coupled Model Intercomparison Project Phase 6 (CMIP6)], and conditioning degrees, several probabilistic attribution analyses were conducted with respect to the 2020-like Mei-yu rainfall and consistently reported a reduced likelihood (by ~50%) due to anthropogenic climate change (63)(64)(65). Revisiting anthropogenic dynamic changes in the models used in the 2020 event attribution, we find that the decreased probability of the underlying circulation patterns in response to anthropogenic forcings is to blame (fig.…”

Section: Discussionmentioning

confidence: 99%

Storyline attribution of human influence on a record-breaking spatially compounding flood-heat event

Wang,

Chen,

Tett

et al. 2023

Sci. Adv.

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Attribution of compound events informs preparedness for emerging hazards with disproportionate impacts. However, the task remains challenging because space-time interactions among extremes and uncertain dynamic changes are not satisfactorily addressed in the well-established attribution framework. For attributing the 2020 record-breaking spatially compounding flood-heat event in China, we conduct a storyline attribution analysis by designing simulation experiments via a weather forecast model, quantifying component-based attributable changes, and comparing with historical flow analogs. We quantify that given the large-scale circulation, anthropogenic influence to date has exacerbated the extreme Mei-yu rainfall in the mid-lower reaches of the Yangtze River during June–July 2020 by ~6.5% and warmed the co-occurring seasonal extreme heat in South China by ~1°C. Our projections show a further intensification of the compound event by the end of this century, with moderate emissions making the rainfall totals ~14% larger and the season ~2.1°C warmer in South China than the 2020 status.

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“…tropical anomalous SST boundary condition plus the long-lasting Madden-Julian Oscillation active phase over the Indian Ocean favored the formation and maintenance of Northwest Pacific (NWP) anomalous anticyclone (AAC) (Takaya et al, 2020;Zhang, Huang, et al, 2021;Zhou et al, 2021). The southeasterlies of AAC intensified the anomalous moisture transport from tropical oceans, thereby persistent intense rainfall over East Aisa as documented by numerous literatures (e.g., Cai et al, 2022;Hu et al, 2017;Liang et al, 2021;Tang et al, 2022;L. Zhang, Zhao, et al, 2021).…”

mentioning

confidence: 91%

Increasing 2020‐Like Boreal Summer Rainfall Extremes Over Northeast Indian Subcontinent Under Greenhouse Warming

Tang

Wang

et al. 2022

Geophysical Research Letters

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Extreme persistent rainfall poses serious impacts on human and natural systems, predominately through its related hydrogeological disasters. Due to sustained heavy downpours, the summer of 2020 was the second wettest on record over Northeast Indian subcontinent since 1901. Here, we find that this orographically anchored extreme rainfall event was largely associated with the anomalous anticyclone (AAC) over the Indo‐Northwest Pacific region and La Niña‐induced Walker circulation intensification. The overall effect of anthropogenic forcings contributed little to the occurrence probability of this event, because the warming and wetting effects of greenhouse gases were almost negated by anthropogenic aerosols. Climate models project a prominent increasing trend of such extreme event under future greenhouse‐induced warming due to increase in atmospheric water vapor and 2020‐like AAC frequency. Our findings thus call for scaling up climate change adaptation efforts for increasingly extreme persistent rainfall in highly populated but low‐resilience South Asian developing countries.

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Reduced Probability of 2020 June–July Persistent Heavy Mei-yu Rainfall Event in the Middle to Lower Reaches of the Yangtze River Basin under Anthropogenic Forcing

Cited by 13 publications

References 9 publications

Impacts of moisture supply from the subtropical western Pacific on the subtropical high and the atmospheric river during the heavy rain of 2020 in Japan

Impacts of moisture supply from the subtropical western Pacific on the subtropical high and the atmospheric river during the heavy rain of 2020 in Japan

Storyline attribution of human influence on a record-breaking spatially compounding flood-heat event

Increasing 2020‐Like Boreal Summer Rainfall Extremes Over Northeast Indian Subcontinent Under Greenhouse Warming

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