Abstract
Accurate prediction of the convection initiation (CI) in urban areas is still a challenge. A heavy rainfall event, missed by the 9-km regional operational modeling system, occurred in the coastal urban area of the Shanghai metropolitan region (SMR) in the late morning on 28 July 2020 on the warm side to the south of the Meiyu front. In this study, observational analyses and convection-permitting simulations with a resolution of 3 km were conducted to investigate the CI mechanism of this rainfall event. The results showed that the CI was due to the interaction of urban heat island (UHI), northwesterly outflows from the Meiyu front precipitation system (MFPS), and northeasterly sea winds. First, the UHI created a lifting condition producing adiabatic cooling and the vertical moisture transport in the urban region. Then, the mesolow generated by the UHI induced and enhanced local low-level convergence near the CI region and accelerated the northwesterly outflows and the northeasterly sea winds as they converged to the UHI. The convection was triggered as a result of the strengthened low-level convergence when the enhanced northwesterly outflows and northeasterly sea winds approached the updraft zone caused by the UHI center. Sensitivity experiments with either the urban area of the SMR removed or the MFPS suppressed further revealed that the enhancement of the low-level convergence was mainly contributed by the UHI. The outflows and sea winds transported cold and moist air to the CI region and partly offset the negative contribution of the urban drying effect to the low-level relative humidity to facilitate the development of the deep moist absolute unstable layer during the CI. In addition, the MFPS also contributed to the enhancement of the northeasterly sea winds by influencing the land–sea pressure contrast on the north of the SMR.
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References
Bornstein, R., and Q. L. Lin, 2000: Urban heat islands and summertime convective thunderstorms in Atlanta: Three case studies. Atmos. Environ., 34, 507–516, doi: https://doi.org/10.1016/S1352-2310(99)00374-X.
Bryan, G. H., and J. M. Fritsch, 2000: Moist absolute instability: The sixth static stability state. Bull. Amer. Meteor. Soc., 81, 1207–1230, doi: https://doi.org/10.1175/1520-0477(2000)081<1287:MAITSS>2.3.CO;2.
Changnon, S. A. Jr., F. A. Huff, and R. G. Semonin, 1971: MET-ROMEX: An investigation of inadvertent weather modification. Bull. Amer. Meteor. Soc., 52, 958–968, doi: https://doi.org/10.1175/1520-0477(1971)052<0958:MAIOIW>2.0.CO;2.
Clark, P., N. Roberts, H. Lean, et al., 2016: Convection-permitting models: A step-change in rainfall forecasting. Meteor. Appl., 23, 165–181, doi: https://doi.org/10.1002/met.1538.
Ding, Y. H., 1992: Summer monsoon rainfalls in China. J. Meteor. Soc. Japan, 70, 373–396, doi: https://doi.org/10.2151/jmsj1965.70.1B_373.
Du, Y., G. X. Chen, B. Han, et al., 2020: Convection initiation and growth at the coast of South China. Part I: Effect of the marine boundary layer jet. Mon. Wea. Rev., 148, 3847–3869, doi: https://doi.org/10.1175/MWR-D-20-0089.1.
Dudhia, J., 1989: Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model. J. Atmos. Sci., 46, 3077–3107, doi: https://doi.org/10.1175/1520-0469(1989)046<3077:NSOCOD>2.0.CO;2.
Feng, J. M., Y. L. Wang, Z. G. Ma, et al., 2012: Simulating the regional impacts of urbanization and anthropogenic heat release on climate across China. J. Climate, 25, 7187–7203, doi: https://doi.org/10.1175/JCLI-D-11-00333.1.
Fu, X. S., X. Q. Yang, and X. G. Sun, 2019: Spatial and diurnal variations of summer hourly rainfall over three super city clusters in eastern China and their possible link to the urbanization. J. Geophys. Res. Atmos., 124, 5445–5462, doi: https://doi.org/10.1029/2019JD030474.
Gero, A. F., and A. J. Pitman, 2006: The impact of land cover change on a simulated storm event in the Sydney basin. J. Appl. Meteor. Climatol., 45, 283–300, doi: https://doi.org/10.1175/JAM2337.1.
Grimm, N. B., S. H. Faeth, N. E. Golubiewski, et al., 2008: Global change and the ecology of cities. Science, 319, 756–760, doi:https://doi.org/10.1126/science.1150195.
Guan, P. Y., G. X. Chen, W. X. Zeng, et al., 2020: Corridors of Mei-Yu-season rainfall over Eastern China. J. Climate, 33, 2603–2626, doi: https://doi.org/10.1175/JCLI-D-19-0649.1.
Guo, X. L., D. H. Fu, and J. Wang, 2006: Mesoscale convective precipitation system modified by urbanization in Beijing city. Atmos. Res., 82, 112–126, doi: https://doi.org/10.1016/j.atmosres.2005.12.007.
He, Z. W., Q. H. Zhang, L. Q. Bai, et al., 2017: Characteristics of mesoscale convective systems in central East China and their reliance on atmospheric circulation patterns. Int. J. Climatol., 37, 3276–3290, doi: https://doi.org/10.1002/joc.4917.
He, Z. W., Q. H. Zhang, K. Zhao, et al., 2018: Initiation and evolution of elevated convection in a nocturnal squall line along the Meiyu front. J. Geophys. Res. Atmos., 123, 7292–7310, doi: https://doi.org/10.1029/2018JD028511.
Hersbach, H., B. Bell, P. Berrisford, et al., 2020: The ERA5 global reanalysis. Quart. J. Roy. Meteor. Soc., 146, 1999–2049, doi: https://doi.org/10.1002/qj.3803.
Hong, S. Y., Y. Noh, and J. Dudhia, 2006: A new vertical diffusion package with an explicit treatment of entrainment processes. Mon. Wea. Rev., 134, 2318–2341, doi: https://doi.org/10.1175/MWR3199.1.
Hua, S. F., X. Xu, and B. J. Chen, 2020: Influence of multiscale orography on the initiation and maintenance of a precipitating convective system in North China: A case study. J. Geophys. Res. Atmos., 125, e2019JD031731, doi: https://doi.org/10.1029/2019JD031731.
Huang, Y. J., Y. B. Liu, Y. W. Liu, et al., 2019: Mechanisms for a record-breaking rainfall in the coastal metropolitan city of Guangzhou, China: Observation analysis and nested very large eddy simulation with the WRF model. J. Geophys. Res. Atmos., 124, 1370–1391, doi: https://doi.org/10.1029/2018JD029668.
Jiang, X. L., Y. L. Luo, D. L. Zhang, et al., 2020: Urbanization enhanced summertime extreme hourly precipitation over the Yangtze River Delta. J. Climate, 33, 5809–5826, doi: https://doi.org/10.1175/JCLI-D-19-0884.1.
Kain, J. S., 2004: The Kain–Fritsch convective parameterization: An update. J. Appl. Meteor. Climatol., 43, 170–181, doi: https://doi.org/10.1175/1520-0450(2004)043<0170:TKCPAU>2.0.CO;2.
Li, H. Q., X. P. Cui, and D. L. Zhang, 2017a: On the initiation of an isolated heavy-rain-producing storm near the central urban area of Beijing metropolitan region. Mon. Wea. Rev., 145, 181–197, doi: https://doi.org/10.1175/MWR-D-16-0115.1.
Li, H. Q., X. P. Cui, and D. L. Zhang, 2017b: Sensitivity of the initiation of an isolated thunderstorm over the Beijing metropolitan region to urbanization, terrain morphology and cold outflows. Quart. J. Roy. Meteor. Soc., 143, 3153–3164, doi: https://doi.org/10.1002/qj.3169.
Liang, P., and Y. H. Ding, 2017: The long-term variation of extreme heavy precipitation and its link to urbanization effects in Shanghai during 1916–2014. Adv. Atmos. Sci., 44, 321–334, doi: https://doi.org/10.1007/s00376-016-6120-0.
Liang, X., S. Miao, J. Li, et al., 2018: SURF: Understanding and predicting urban convection and haze. Bull. Amer. Meteor. Soc., 99, 1391–1413, doi: https://doi.org/10.1175/BAMS-D-16-0178.1.
Liu, W. D., H. L. You, and J. X. Dou, 2009: Urban-rural humidity and temperature differences in the Beijing area. Theor. Appl. Climatol., 96, 201–207, doi: https://doi.org/10.1007/s00704-008-0024-6.
Luo, L. P., M. Xue, and K. F. Zhu, 2020: The initiation and organization of a severe hail-producing mesoscale convective system in East China: A numerical study. J. Geophys. Res. Atmos., 125, e2020JD032606, doi: https://doi.org/10.1029/2020JD032606.
Luo, X., M. Xue, and J. F. Fei, 2018: Simulation and analysis of the initiation of a squall line within a Meiyu frontal system in East China. Atmosphere, 9, 183, doi: https://doi.org/10.3390/atmos9050183.
Luo, Y. L., and Y. R. X. Chen, 2015: Investigation of the predictability and physical mechanisms of an extreme-rainfall-producing mesoscale convective system along the Meiyu front in East China: An ensemble approach. J. Geophys. Res. Atmos., 120, 10,593–10,618, doi: https://doi.org/10.1002/2015JD023584.
Luo, Y. L., Y. Gong, and D. L. Zhang, 2014: Initiation and organizational modes of an extreme-rain-producing mesoscale convective system along a Mei-Yu front in East China. Mon. Wea. Rev., 142, 203–221, doi: https://doi.org/10.1175/MWR-D-13-00111.1.
Luo, Y. L., J. H. Zhang, M. Yu, et al., 2023: On the influences of urbanization on the extreme rainfall over Zhengzhou on 20 July 2021: A convection-permitting ensemble modeling study. Adv. Atmos. Sci., 40, 393–409, doi: https://doi.org/10.1007/s00376-022-2048-8.
Miao, S. G., F. Chen, Q. C. Li, et al., 2011: Impacts of urban processes and urbanization on summer precipitation: A case study of heavy rainfall in Beijing on 1 August 2006. J. Appl. Meteor. Climatol, 50, 806–825, doi: https://doi.org/10.1175/2010JAMC2513.1.
Mlawer, E. J., S. J. Taubman, P. D. Brown, et al., 1997: Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res. Atmos., 102, 16,663–16,682, doi: https://doi.org/10.1029/97JD00237.
Niu, G. Y., Z. L. Yang, K. E. Mitchell, et al., 2011: The community Noah land surface model with multiparameterization options (Noah-MP): 1. Model description and evaluation with local-scale measurements. J. Geophys. Res. Atmos., 116, D12109, doi: https://doi.org/10.1029/2010JD015139.
Niyogi, D., P. Pyle, M. Lei, et al., 2011: Urban modification of thunderstorms: An observational storm climatology and model case study for the Indianapolis urban region. J. Appl. Meteor. Climatol., 50, 1129–1144, doi: https://doi.org/10.1175/2010JAMC1836.1.
Nystrom, R. G., and F. Q. Zhang, 2019: Practical uncertainties in the limited predictability of the record-breaking intensification of Hurricane Patricia (2015). Mon. Wea. Rev., 147, 3535–3556, doi: https://doi.org/10.1175/MWR-D-18-0450.1.
Ooi, M. C. G., A. Chan, K. Subramaniam, et al., 2017: Interaction of urban heating and local winds during the calm intermonsoon seasons in the tropics. J. Geophys. Res. Atmos., 122, 11,499–11,523, doi: https://doi.org/10.1002/2017JD026690.
Rozoff, C. M., W. R. Cotton, and J. O. Adegoke, 2003: Simulation of St. Louis, Missouri, land use impacts on thunderstorms. J. Appl. Meteor. Climatol., 42, 716–738, doi: https://doi.org/10.1175/1520-0450(2003)042<0716:SOSLML>2.0.CO;2.
Schumacher, R. S., and R. H. Johnson, 2008: Mesoscale processes contributing to extreme rainfall in a midlatitude warm-season flash flood. Mon. Wea. Rev., 136, 3964–3986, doi: https://doi.org/10.1175/2008MWR2471.1.
Skamarock, W. C., J. B. Klemp, J. Dudhia, et al., 2021: A Description of the Advanced Research WRF Model Version 4.3. NCAR Tech, Note, NCAR/TN-556+STR, 145 pp, doi:https://doi.org/10.5065/1dfh-6p97.
Song, X. M., J. Y. Zhang, A. AghaKouchak, et al., 2014: Rapid urbanization and changes in spatiotemporal characteristics of precipitation in Beijing metropolitan area. J. Geophys. Res. Atmos., 119, 11,250–11,271, doi: https://doi.org/10.1002/2014JD022084.
Sun, X. Y., Y. L. Luo, X. Y. Gao, et al., 2021: On the localized extreme rainfall over the Great Bay Area in South China with complex topography and strong UHI effects. Mon. Wea. Rev., 149, 2777–2801, doi: https://doi.org/10.1175/MWR-D-21-0004.1.
Tan, J. G., L. M. Yang, C. S. B. Grimmond, et al., 2015: Urban integrated meteorological observations: Practice and experience in Shanghai, China. Bull. Amer. Meteor. Soc., 96, 85–102, doi: https://doi.org/10.1175/BAMS-D-13-00216.1.
Thompson, G., P. R. Field, R. M. Rasmussen, et al., 2008: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part II: Implementation of a new snow parameterization. Mon. Wea. Rev., 136, 5095–5115, doi: https://doi.org/10.1175/2008MWR2387.1.
Toth, Z., and E. Kalnay, 1993: Ensemble forecasting at NMC: The generation of perturbations. Bull. Amer. Meteor. Soc., 74, 2317–2330, doi: https://doi.org/10.1175/1520-0477(1993)074<2317:EFANTG>2.0.CO;2.
Trier, S. B., C. A. Davis, D. A. Ahijevych, et al., 2006: Mechanisms supporting long-lived episodes of propagating nocturnal convection within a 7-Day WRF model simulation. J. Atmos. Sci., 63, 2437–2461, doi: https://doi.org/10.1175/JAS3768.1.
Wang, J., J. M. Feng, and Z. W. Yan, 2015: Potential sensitivity of warm season precipitation to urbanization extents: Modeling study in Beijing-Tianjin-Hebei urban agglomeration in China. J. Geophys.Res. Atmos., 120, 9408–9425, doi: https://doi.org/10.1002/2015JD023572.
Wang, Q. W., Y. Zhang, K. F. Zhu, et al., 2021: A case study of the initiation of parallel convective lines back-building from the south side of a Mei-yu front over complex terrain. Adv. Atmos. Sci., 38, 717–736, doi: https://doi.org/10.1007/s00376-020-0216-2.
Weckwerth, T. M., 2000: The effect of small-scale moisture variability on thunderstorm initiation. Mon. Wea. Rev., 128, 4017–4030, doi: https://doi.org/10.1175/11520-0493(2000)/29<4017:TEOSSM>2.0.CO;2.
Wei, M. Z., Z. Toth, R. Wobus, et al., 2008: Initial perturbations based on the ensemble transform (ET) technique in the NCEP global operational forecast system. Tellus A, 60, 62–79, doi:https://doi.org/10.1111/j.1600-0870.2007.00273.x.
Williams, A. P., R. E. Schwartz, S. Iacobellis, et al., 2015: Urbanization causes increased cloud base height and decreased fog in coastal Southern California. Geophys. Res. Lett., 22, 1527–1536, doi: https://doi.org/10.1002/2015GL063266.
Wong, K. K., and R. A. Dirks, 1978: Mesoscale perturbations on airflow in the urban mixing layer. J. Appl. Meteor. Climatol., 17, 677–688, doi: https://doi.org/10.1175/1520-0450(1978)017<0677:MPOAIT>2.0.CO;2.
Wu, M. W., and Y. L. 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, 719–736, doi: https://doi.org/10.1007/s13351-016-6089-8.
Wu, M. W., Y. L. Luo, F. Chen, et al., 2019: Observed link of extreme hourly precipitation changes to urbanization over coastal South China. J. Appl. Meteor. Climatol., 58, 1799–1819, doi: https://doi.org/10.1175/JAMC-D-18-0284.1.
Wu, Y. L., J. Z. Sun, Z. M. Ying, et al., 2021: Effects of local-scale orography and urban heat island on the initiation of a record-breaking rainfall event. J. Geophys. Res. Atmos., 126, e2021JD034839, doi: https://doi.org/10.1029/2021JD034839.
Xu, X. D., G. A. Ding, L. G. Bian, et al., 2004: Characteristics of atmospheric envinronment of boundary layer structure of city community in BECAPEX and integrate influence. Acta Meteor. Sinica, 62, 663–671, doi: https://doi.org/10.11676/qxxb2004.064. (in Chinese)
Yang, L., J. A. Smith, M. L. Baeck, et al., 2014: Impact of urbanization on heavy convective precipitation under strong large-scale forcing: A case study over the Milwaukee-Lake Michigan region. J. Hydrometeor., 15, 261–278, doi: https://doi.org/10.1175/JHM-D-13-020.1.
Yang, L., J. Smith, and D. Niyogi, 2019: Urban impacts on extreme monsoon rainfall and flooding in complex terrain. Geophys. Res. Lett., 46, 5918–5927, doi: https://doi.org/10.1029/2019GL083363.
Yang, P., G. Y. Ren, and P. C. Yan, 2017a: Evidence for a strong association of short-duration intense rainfall with urbanization in the Beijing urban area. J. Climate, 30, 5851–5870, doi: https://doi.org/10.1175/JCLI-D-16-0671.1.
Yang, P., G. Y. Ren, and W. Hou, 2017b: Temporal-spatial patterns of relative humidity and the urban dryness island effect in Beijing city. J. Appl. Meteor. Climatol., 56, 2221–2237, doi: https://doi.org/10.1175/JAMC-D-16-0338.1.
Yin, J. F., D. L. Zhang, Y. L. Luo, et al., 2020: On the extreme rainfall event of 7 May 2017 over the coastal city of Guangzhou. Part I: Impacts of urbanization and orography. Mon. Wea. Rev., 148, 955–979, doi: https://doi.org/10.1175/MWR-D-19-0212.1.
Yu, M., and Y. M. Liu, 2015: The possible impact of urbanization on a heavy rainfall event in Beijing. J. Geophys. Res. Atmos., 120, 8132–8143, doi: https://doi.org/10.1002/2015JD023336.
Zhang, C. L., F. Chen, S. G. Miao, et al., 2009: Impacts of urban expansion and future green planting on summer precipitation in the Beijing metropolitan area. J. Geophys. Res. Atmos., 114, D02116, doi: https://doi.org/10.1029/2008JD010328.
Zhang, D. L., 2020: Rapid urbanization and more extreme rainfall events. Sci. Bull., 65, 516–518, doi: https://doi.org/10.1016/j.scib.2020.02.002.
Zhang, D. L., Y. X. Shou, R. R. Dickerson, et al., 2011: Impact of upstream urbanization on the urban heat island effects along the Washington-Baltimore corridor. J. Appl. Meteor. Climatol., 50, 2012–2029, doi: https://doi.org/10.1175/JAMC-D-10-05008.1.
Zhang, M., and D. L. Zhang, 2012: Subkilometer simulation of a torrential-rain-producing mesoscale convective system in East China. Part I: Model verification and convective organization. Mon. Wea. Rev., 140, 184–201, doi: https://doi.org/10.1175/MWR-D-11-00029.1.
Zhang, M. R., Z. Y. Meng, Y. P. Huang, et al., 2019: The mechanism and predictability of an elevated convection initiation event in a weak-lifting environment in central-eastern China. Mon. Wea. Rev., 147, 1823–1841, doi: https://doi.org/10.1175/MWR-D-18-0400.1.
Zhang, X., Y. H. Yang, B. D. Chen, et al., 2021: Operational precipitation forecast over China using the Weather Research and Forecasting (WRF) model at a gray-zone resolution: Impact of convection parameterization. Wea. Forecasting, 36, 915–928, doi: https://doi.org/10.1175/WAF-D-20-0210.1.
Zhang, Y. Z., S. G. Miao, Y. J. Dai, et al., 2017: Numerical simulation of urban land surface effects on summer convective rainfall under different UHI intensity in Beijing. J. Geophys. Res. Atmos., 122, 7851–7868, doi: https://doi.org/10.1002/2017JD026614.
Zhou, X. Q., Y. J. Zhu, D. C. Hou, et al., 2017: Performance of the new NCEP Global Ensemble Forecast System in a parallel experiment. Wea. Forecasting, 32, 1989–2004, doi: https://doi.org/10.1175/WAF-D-17-0023.1.
Acknowledgments
The authors are grateful to NCEP for providing the NCEP-GEFS data (https://www.nco.ncep.noaa.gov/pmb/products/gens/) and to ECMWF for providing the ERA5 data (https://cds.climate.copernicus.eu). The authors are thankful to the editor, two anonymous reviewers, and Dr. Qiuping Wang for their help improving the manuscript.
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Supported by the National Key Research and Development Program of China (2017YFC1501902) and Natural Science Foundation of Shanghai Science and Technology Committee (21ZR1457700).
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Gao, Y., Wang, X., Xie, Y. et al. Convection Initiation of a Heavy Rainfall Event in the Coastal Metropolitan Region of Shanghai on the South Side of the Meiyu Front. J Meteorol Res 37, 149–173 (2023). https://doi.org/10.1007/s13351-023-2161-3
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DOI: https://doi.org/10.1007/s13351-023-2161-3