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国家级多源融合降水产品在汉江航道的适用性研究

Applicability study of national multi-source merged precipitation products in the Hanjiang waterway

  • 摘要: 为评估国家级多源融合降水产品(ART_5 km、ART_1 km,以下简称为两种产品)在汉江航道的适用性,本文采用二分类和连续变量指标,从对降水识别、降水强度、时空分布差异及典型降水过程等方面,系统检验2022—2023年两种产品在汉江航道的适用性。结果表明:(1) 两种产品对有无降水的识别能力有限,但在已发生降水的样本中,与气象观测站的相关性均较好,仅存在轻微系统性低估(小时尺度:-0.2 mm·h-1;日尺度:-0.3 mm·d-1),整体稳定性良好。(2) 两种产品对降水强度依赖性明显。对弱降水(<2 mm·h-1或小雨)识别和估测最优;小时尺度上,强降水系统性低估明显,极端降水易出现漏报;日尺度上,中雨及以上降水相关性仍较好(R>0.9)。(3) 空间分异特征显著。上游定量估测误差最明显;中游航段二分类识别最优;下游在强降水下识别性能下降且误差集中,但对过程演变捕捉能力仍较好。(4) 时间差异明显。弱降水全年误差最小且稳定;中等强度降水(2~20 mm·h-1或中到大雨)在3—4月、9—10月识别准确率最佳且定量估测偏差较小;强降水6—8月识别较优,但存在空间离散大、午后误差大和极端降水部分漏报等问题。(5) 典型降水过程分析显示,两种产品均能够有效捕捉汉江航道降水的时空演变特征(雨带移动、强降水中心位置与结构),ART_5km对20 mm·h-1以下降水的监测更优,ART_1km在强降水识别中更具优势。研究结果证明ART_5 km和ART_1 km产品可为汉江航道不同风险等级航运预警提供数据支撑,强降水经阈值优化后仍具参考价值。

     

    Abstract: To evaluate the applicability of national-level multi-source merged precipitation products (ART_5 km and ART_1 km, hereinafter referred to as the two products) over the Hanjiang waterway, this study employs binary (categorical) and continuous-variable metrics to systematically assess their performance over the Hanjiang waterway during 2022–2023, in terms of precipitation detection, intensity estimation, spatiotemporal distribution differences, and typical precipitation events. The results show that: (1) The two products exhibit limited skill in distinguishing the occurrence of precipitation; however, for samples where precipitation has actually occurred, both show good correlations with meteorological station observations, with only slight systematic underestimation (hourly scale: −0.2 mm·h-1; daily scale: −0.3 mm·d-1), indicating good overall stability. (2) The performance of both products depends markedly on precipitation intensity. They perform best in detecting and estimating weak precipitation (<2 mm·h-1 or light rain); at the hourly scale, heavy precipitation is subject to pronounced systematic underestimation, and extreme precipitation is prone to missed detection, whereas at the daily scale, precipitation of moderate rain and above still shows good correlations (R > 0.9). (3) Spatial variability is significant. The upper reaches show the largest quantitative estimation errors; the middle reaches yield the best binary detection performance; the lower reaches show degraded detection skill and concentrated errors under heavy precipitation, though the ability to capture process evolution remains satisfactory. (4) Temporal differences are evident. Weak precipitation has the smallest and most stable errors throughout the year; moderate-intensity precipitation (2~20 mm·h-1, or moderate to heavy rain) is best detected during March–April and September–October, with relatively small quantitative biases; heavy precipitation is better detected during June–August, though accompanied by large spatial dispersion, large afternoon errors, and partial missed detection of extreme precipitation. (5) Analysis of typical precipitation events shows that both products can effectively capture the spatiotemporal evolution of precipitation over the Hanjiang waterway (rainband movement, location and structure of heavy precipitation centers); ART_5 km performs better in monitoring precipitation below 20 mm·h-1, while ART_1 km has advantages in heavy precipitation detection. These results demonstrate that the ART_5 km and ART_1 km products can provide data support for shipping warnings at different risk levels along the Hanjiang waterway, and that heavy precipitation estimates, after threshold optimization, remain of reference value.

     

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