Multiscale Features and Triggering Mechanisms of the Warm-Sector Heavy Rainfall Accompanied by Warm Shear Along the Yangtze–Huaihe Coastal Regions

Yiping Yu aKey Laboratory of Meteorology Disaster, Ministry of Education, Joint International Research Laboratory of Climate and Environment Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China

Search for other papers by Yiping Yu in
Current site
Google Scholar
PubMed
Close
https://orcid.org/0009-0001-0322-2560
,
Ling Zhang aKey Laboratory of Meteorology Disaster, Ministry of Education, Joint International Research Laboratory of Climate and Environment Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China

Search for other papers by Ling Zhang in
Current site
Google Scholar
PubMed
Close
,
Liuxian Song bSuqian Meteorological Bureau, Suqian, China

Search for other papers by Liuxian Song in
Current site
Google Scholar
PubMed
Close
,
Wei Li aKey Laboratory of Meteorology Disaster, Ministry of Education, Joint International Research Laboratory of Climate and Environment Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China

Search for other papers by Wei Li in
Current site
Google Scholar
PubMed
Close
,
Lu Zhou cChangsha Meteorological Bureau, Changsha, China

Search for other papers by Lu Zhou in
Current site
Google Scholar
PubMed
Close
, and
Lin Ouyang dInstitute for Climate and Application Research, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China

Search for other papers by Lin Ouyang in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Using high-resolution hourly precipitation data and ERA5 reanalysis data, this study employs the K-means method to categorize 32 cases of warm-sector heavy rainfall events accompanied by a warm-type shear line (WSWR) along the Yangtze–Huaihe coastal region (YHCR) from April to September during 2010–17. Considering the synoptic system features of WSWR by K means, the result reveals 15 southwest type (SW-type) and 17 south-biased type (S-type) WSWR events. Composite analysis illuminates the distinct dynamic and thermodynamic features of each type. For the SW-type WSWR, the maximum value of water vapor is concentrated around 850 hPa in the lower troposphere. The YHCR is located at the intersection of the exit area of the 850-hPa synoptic low-level jet (LLJ) and the entrance area of the 600-hPa jet. The suction effects, combined with the location of YHCR on the left side of the boundary layer jet (BLJ), facilitate the triggering of local convection. Conversely, the S-type WSWR shows peak water vapor in the boundary layer. Before the onset of WSWR events, a warm, humid tongue indicated by pseudoequivalent potential temperature θse is present in the boundary layer, signified by substantial unstable energy. The BLJ aids mesoscale ascent on its terminus, enhancing convergence along the coastline. The BLJ also channels unstable energy and water vapor to the YHCR, causing significant rainfall. Typical case studies of both types show similar environmental backgrounds. The scale analysis shows mesoscales of dynamic field are crucial in shaping both types of WSWR, while the large-scale and meso-α-scale dynamic field facilitate the transportation of moist and warm airflow.

© 2024 American Meteorological Society. This published article is licensed under the terms of the default AMS reuse license. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Ling Zhang, lingzhang@nuist.edu.cn

Abstract

Using high-resolution hourly precipitation data and ERA5 reanalysis data, this study employs the K-means method to categorize 32 cases of warm-sector heavy rainfall events accompanied by a warm-type shear line (WSWR) along the Yangtze–Huaihe coastal region (YHCR) from April to September during 2010–17. Considering the synoptic system features of WSWR by K means, the result reveals 15 southwest type (SW-type) and 17 south-biased type (S-type) WSWR events. Composite analysis illuminates the distinct dynamic and thermodynamic features of each type. For the SW-type WSWR, the maximum value of water vapor is concentrated around 850 hPa in the lower troposphere. The YHCR is located at the intersection of the exit area of the 850-hPa synoptic low-level jet (LLJ) and the entrance area of the 600-hPa jet. The suction effects, combined with the location of YHCR on the left side of the boundary layer jet (BLJ), facilitate the triggering of local convection. Conversely, the S-type WSWR shows peak water vapor in the boundary layer. Before the onset of WSWR events, a warm, humid tongue indicated by pseudoequivalent potential temperature θse is present in the boundary layer, signified by substantial unstable energy. The BLJ aids mesoscale ascent on its terminus, enhancing convergence along the coastline. The BLJ also channels unstable energy and water vapor to the YHCR, causing significant rainfall. Typical case studies of both types show similar environmental backgrounds. The scale analysis shows mesoscales of dynamic field are crucial in shaping both types of WSWR, while the large-scale and meso-α-scale dynamic field facilitate the transportation of moist and warm airflow.

© 2024 American Meteorological Society. This published article is licensed under the terms of the default AMS reuse license. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Ling Zhang, lingzhang@nuist.edu.cn
Save
  • Barnes, S. L., 1973: Mesoscale objective map analysis using weighted time-series observations. NOAA Tech. Memo. ERL NSSL-62, 66 pp., https://repository.library.noaa.gov/view/noaa/17647/noaa_17647_DS1.pdf.

  • Bolton, D., 1980: The computation of equivalent potential temperature. Mon. Wea. Rev., 108, 10461053, https://doi.org/10.1175/1520-0493(1980)108<1046:TCOEPT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Chen, Y., and P. Zhai, 2014: Two types of typical circulation pattern for persistent extreme precipitation in central–eastern China. Quart. J. Roy. Meteor. Soc., 140, 14671478, https://doi.org/10.1002/qj.2231.

    • Search Google Scholar
    • Export Citation
  • Chen, Y., Y. Chen, T. Chen, and H. He, 2016: Characteristics analysis of warm-sector rainstorms over the middle-lower reaches of the Yangtze River. Meteor. Monogr., 42 (6), 724731.

    • Search Google Scholar
    • Export Citation
  • Chen, Y., Y. Luo, and B. Liu, 2022: General features and synoptic-scale environments of mesoscale convective systems over South China during the 2013–2017 pre-summer rainy seasons. Atmos. Res., 266, 105954, https://doi.org/10.1016/j.atmosres.2021.105954.

    • Search Google Scholar
    • Export Citation
  • Dong, F., X. Zhi, L. Zhang, and C. Ye, 2021: Diurnal variations of coastal boundary layer jets over the northern South China Sea and their impacts on diurnal cycle of rainfall over southern China during the early-summer rainy season. Mon. Wea. Rev., 149, 33413363, https://doi.org/10.1175/MWR-D-20-0292.1.

    • Search Google Scholar
    • Export Citation
  • Draxler, R., and G. D. Hess, 1998: An overview of the HYSPLIT_4 modelling system for trajectories, dispersion, and deposition. Aust. Meteor. Mag., 47, 295308.

    • Search Google Scholar
    • Export Citation
  • Draxler, R., B. Stunder, G. Rolph, A. Stein, and A. Taylor, 2009: HYSPLIT4 User’s Guide. NOAA Air Resources Laboratory, 316 pp., http://www.arl.noaa.gov/documents/reports/hysplit_user_guide.pdf.

  • Du, Y., and G. Chen, 2019a: Heavy rainfall associated with double low-level jets over southern China. Part II: Convection initiation. Mon. Wea. Rev., 147, 543565, https://doi.org/10.1175/MWR-D-18-0102.1.

    • Search Google Scholar
    • Export Citation
  • Du, Y., and G. Chen, 2019b: Climatology of low-level jets and their impact on rainfall over southern China during the early-summer rainy season. J. Climate, 32, 88138833, https://doi.org/10.1175/JCLI-D-19-0306.1.

    • Search Google Scholar
    • Export Citation
  • Du, Y., G. Chen, B. Han, L. Bai, and M. Li, 2020: Convection initiation and growth at the coast of South China. Part II: Effects of the terrain, coastline, and cold pools. Mon. Wea. Rev., 148, 38713892, https://doi.org/10.1175/MWR-D-20-0090.1.

    • Search Google Scholar
    • Export Citation
  • Du, Y., Y. Shen, and G. Chen, 2022: Influence of coastal marine boundary layer jets on rainfall in South China. Adv. Atmos. Sci., 39, 782801, https://doi.org/10.1007/s00376-021-1195-7.

    • Search Google Scholar
    • Export Citation
  • Fang, Y., H. Chen, Y. Lin, C. Zhao, Y. Lin, and F. Zhou, 2021: Classification of northeast China cold vortex activity paths in early summer based on K-means clustering and their climate impact. Adv. Atmos. Sci., 38, 400412, https://doi.org/10.1007/s00376-020-0118-3.

    • Search Google Scholar
    • Export Citation
  • Hersbach, H., and Coauthors, 2020: The ERA5 global reanalysis. Quart. J. Roy. Meteor. Soc., 146, 19992049, https://doi.org/10.1002/qj.3803.

    • Search Google Scholar
    • Export Citation
  • Huang, S. S., 1986: The Heavy Rain during the Pre-summer Period Over Southern China (in Chinese). Guangdong Technology Press, 244 pp.

  • Kim, M., and R. S. Ramakrishna, 2005: New indices for cluster validity assessment. Pattern Recognit. Lett., 26, 23532363, https://doi.org/10.1016/j.patrec.2005.04.007.

    • Search Google Scholar
    • Export Citation
  • Liu, X., Y. Luo, L. Huang, D.-L. Zhang, and Z. Guan, 2020: Roles of double low-level jets in the generation of coexisting inland and coastal heavy rainfall over South China during the presummer rainy season. J. Geophys. Res. Atmos., 125, e2020JD032890, https://doi.org/10.1029/2020JD032890.

    • Search Google Scholar
    • Export Citation
  • Luo, Y., and Coauthors, 2017: The Southern China Monsoon Rainfall Experiment (SCMREX). Bull. Amer. Meteor. Soc., 98, 9991013, https://doi.org/10.1175/BAMS-D-15-00235.1.

    • Search Google Scholar
    • Export Citation
  • Ning, G., and Coauthors, 2023: Large-scale moisture transport and local-scale convection patterns associated with warm-sector heavy rainfall over South China. Atmos. Res., 285, 106637, https://doi.org/10.1016/j.atmosres.2023.106637.

    • Search Google Scholar
    • Export Citation
  • Rousseeuw, P. J., 1987: Silhouettes: A graphical aid to the interpretation and validation of cluster analysis. J. Comput. Appl. Math., 20, 5365, https://doi.org/10.1016/0377-0427(87)90125-7.

    • Search Google Scholar
    • Export Citation
  • Shen, Y., P. Zhao, Y. Pan, and J. Yu, 2014: A high spatiotemporal gauge-satellite merged precipitation analysis over China. J. Geophys. Res. Atmos., 119, 30633075, https://doi.org/10.1002/2013JD020686.

    • Search Google Scholar
    • Export Citation
  • Shi, Y., Z. Jiang, Z. Liu, and L. Li, 2020: A Lagrangian analysis of water vapor sources and pathways for precipitation in East China in different stages of the East Asian summer monsoon. J. Climate, 33, 977992, https://doi.org/10.1175/JCLI-D-19-0089.1.

    • Search Google Scholar
    • Export Citation
  • Song, L., L. Zhang, Q. Ma, F. Dong, and X. Zhi, 2022: Objective identification and analysis of warm-sector rainstorm with warm shear pattern over Yangtze-Huaihe River region. Chin. J. Atmos. Sci., 47, 1709–1722, https://doi.org/10.3878/j.issn.1006-9895.2207.21220.

    • Search Google Scholar
    • Export Citation
  • Sun, J., Y. Zhang, R. Liu, S. Fu, and F. Tian, 2019: A review of research on warm-sector heavy rainfall in China. Adv. Atmos. Sci., 36, 12991307, https://doi.org/10.1007/s00376-019-9021-1.

    • Search Google Scholar
    • Export Citation
  • Wu, M., and Y. Luo, 2016: Mesoscale observational analysis of lifting mechanism of a warm-sector convective system producing the maximal daily precipitation in China mainland during pre-summer rainy season of 2015. J. Meteor. Res., 30, 719736, https://doi.org/10.1007/s13351-016-6089-8.

    • Search Google Scholar
    • Export Citation
  • Xin, F., D. Peng, R. Liu, and S. C. Liu, 2022: Moisture sources for the weather pattern classified extreme precipitation in the first rainy season over South China. Int. J. Climatol., 42, 60276041, https://doi.org/10.1002/joc.7576.

    • Search Google Scholar
    • Export Citation
  • Zhan, R.-F., J.-P. Li, J.-H. He, and L. Qi, 2008: A case study of double ridges of subtropical high over the western North Pacific: The role in the 1998 second Mei-Yu over the Yangtze River valley. J. Meteor. Soc. Japan, 86, 167181, https://doi.org/10.2151/jmsj.86.167.

    • Search Google Scholar
    • Export Citation
  • Zhang, F., Q. Zhang, Y. Du, and H. Kong, 2018: Characteristics of coastal low-level jets in the Bohai Sea, China, during the early warm season. J. Geophys. Res. Atmos., 123, 13 76313 774, https://doi.org/10.1029/2018JD029242.

    • Search Google Scholar
    • Export Citation
  • Zhang, L., D. Zhao, T. Zhou, D. Peng, and C. Xiao, 2021: Moisture origins and transport processes for the 2020 Yangtze River valley record-breaking Mei-Yu rainfall. Adv. Atmos. Sci., 38, 21252136, https://doi.org/10.1007/s00376-021-1097-8.

    • Search Google Scholar
    • Export Citation
  • Zhang, L., X. Ma, S. Zhu, Z. Guo, X. Zhi, and C. Chen, 2022: Analyses and applications of the precursor signals of a kind of warm sector heavy rainfall over the coast of Guangdong, China. Atmos. Res., 280, 106425, https://doi.org/10.1016/j.atmosres.2022.106425.

    • Search Google Scholar
    • Export Citation
  • Zhao, Y., J. Cheng, G. Feng, R. Zhi, Z. Zheng, and Z. Zhang, 2022: Analysis of the atmospheric direct dynamic source for the westerly extended WPSH and record-breaking plum rain in 2020. Climate Dyn., 59, 12331251, https://doi.org/10.1007/s00382-022-06186-4.

    • Search Google Scholar
    • Export Citation
  • Zhou, T.-J., and R.-C. Yu, 2005: Atmospheric water vapor transport associated with typical anomalous summer rainfall patterns in China. J. Geophys. Res., 110, D08104, https://doi.org/10.1029/2004JD005413.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 242 242 16
Full Text Views 96 96 7
PDF Downloads 82 82 10