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<p>Drought and flood are not only related to the frequency and intensity of precipitation, but also have a good relationship with the duration of precipitation on multiple timescales. Based on the daily precipitation data from 391 stations and the monthly ERA-5 reanalysis data over Southwest China from June to August during 1981–2023, this study investigates the multi-timescale variability of precipitation duration in the region. The results reveal that the characteristics of multi-timescale variability in precipitation duration are particularly pronounced over the Yunnan-Guizhou Plateau (YGP), which is thus selected for detailed analysis. By examining the associated large-scale circulation patterns and their relationship with SSTA, the possible causes underlying the multi-timescale characteristics of precipitation duration are elucidated. It is found that: on the inter-decadal time scale, the positive phase of PDO favors the formation of anomalous anticyclonic circulation over the Bay of Bengal at 700&#xa0;hPa, which facilitates the transport of water vapor from the Bay of Bengal to the YGP, and resulting in longer durations of summer precipitation in the region. On the inter-annual time scale, the anomalous warming of SST in the equatorial western Indian Ocean favors the intensification of westerly anomalies over the northern Bay of Bengal, which facilitates the transport of water vapor from the Indian Ocean to the YGP, and causing the longer duration of summer precipitation.</p>

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Multi-timescale characteristics and possible causes of summer precipitation duration in Southwest China

  • 期刊论文

  • 发表日期：

    2026年1月9日

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  • Jie Zhou,
  • Junhu Zhao,
  • Yonghua Li,
  • Hongyv Tang,
  • Guolin Feng

摘要

Drought and flood are not only related to the frequency and intensity of precipitation, but also have a good relationship with the duration of precipitation on multiple timescales. Based on the daily precipitation data from 391 stations and the monthly ERA-5 reanalysis data over Southwest China from June to August during 1981–2023, this study investigates the multi-timescale variability of precipitation duration in the region. The results reveal that the characteristics of multi-timescale variability in precipitation duration are particularly pronounced over the Yunnan-Guizhou Plateau (YGP), which is thus selected for detailed analysis. By examining the associated large-scale circulation patterns and their relationship with SSTA, the possible causes underlying the multi-timescale characteristics of precipitation duration are elucidated. It is found that: on the inter-decadal time scale, the positive phase of PDO favors the formation of anomalous anticyclonic circulation over the Bay of Bengal at 700 hPa, which facilitates the transport of water vapor from the Bay of Bengal to the YGP, and resulting in longer durations of summer precipitation in the region. On the inter-annual time scale, the anomalous warming of SST in the equatorial western Indian Ocean favors the intensification of westerly anomalies over the northern Bay of Bengal, which facilitates the transport of water vapor from the Indian Ocean to the YGP, and causing the longer duration of summer precipitation.