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长三角地区强对流天气下对流性大风环境参数特征

Environmental Parameters of Severe Convective Winds under Convection Fields over the Yangtze River Delta

  • 摘要: 对流性大风是长三角地区频发的强对流灾害性天气之一,具有突发性强、局地性显著和破坏力大等特征,对社会经济与人民生命财产安全构成严重威胁。然而,当前业务预报对对流性大风的预报评分普遍较低,亟需探索更具区域适应性的潜势预报方法。本文基于2016–2022年长三角地区八级以上对流性大风个例资料,系统分析了大风发生的大气环境特征,重点比较了传统物理量参数与新构建参数在随机森林模型中的判别性能。结果表明,单一热力或动力参数的判别能力有限,而基于物理机制启发构建的新参数在特征重要性排序中显著领先,体现了多参数融合的有效性。随机森林模型在样本有限的条件下仍表现稳健,在常规测试集(2016–2021)和独立验证集(2022)上的AUC值分别达到0.792与0.744的AUC。尽管模型总体精确率偏低,但召回率较高,表明其对大风事件具有较强的捕捉能力。研究表明,冷池强度、中低层温度递减率、垂直风切变和相对湿度等因子是影响长三角地区对流性大风发生的关键环境要素。本研究尝试构建新参数LR04SHIP、LR16CAPE、RH02SHIP显著提升了潜势预报的物理可解释性与应用价值,为完善区域化对流性大风预报指标体系、提升灾害性天气预警能力提供了科学参考依据。

     

    Abstract: Severe convective winds (also known as thunderstorm gusts) represent a frequent hazardous convective weather phenomena in the Yangtze Reiver Delta region of China. Known for their sudden onset, high locality, and destructive potential, these events pose serious threats to economic activities public safety. However, operational forecasting of such winds remains challenging, with generally low prediction scores, indicating an urgent need for more regionally adaptive potential forecast methods. Using documented cases of level-8 or above severe convective winds (≥17.2 m/s) in the Yangtze River Delta from 2016 to 2022, this study systematically examined the environmental conditions associated with these severe wind events with a particular focus on comparing the performance of conventional physical parameters and newly developed predictors within a random forest framework. The results show that individual thermodynamic or dynamic parameters have limited discriminative power, whereas the newly constructed parameters, designed based on physical mechanisms, rank highly in feature importance, demonstrating the value of parameter integration. The random forest model performs robustly even with a limited sample size, achieving AUC values of 0.792 on the conventional test set (2016–2021) and 0.744 on an independent validation et (2022). Although the overall precision is relatively low, the high recall rate indicates a strong ability to capture severe wind events. The study identifies cold pool intensity, mid-low layer lapse rates, vertical wind shear, relative humidity as key factors influencing severe convective wind occurrence in the Yangtze River Delta. These findings suggest that the new parameters LR04SHIP,LR16CAPE and RH02SHIP proposed in this study enhance the interpretability and practical utility of convective wind forecasting, thereby, providing a scientific basis for improving region-specific prediction indicators and early warning capabilities for severe convective weather.

     

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