《海洋预报》| 暖季华北及周边沿海地区低空急流的统计特征

暖季华北及周边沿海地区低空急流的统计特征

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作者：熊书梦^{1 2 3}赵宇^{1 2}

单位：

1. 南京信息工程大学气候系统预测与变化应对全国重点实验室/气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏南京 210044;
2. 南京信息工程大学大气科学学院, 江苏南京 210044;
3. 广西壮族自治区气象科学研究所, 广西南宁 530022

分类号：P458

出版年·卷·期（页码）：2025·42·第六期（83-94）

摘要：利用2008—2023年欧洲中期天气预报中心0.25°×0.25°的1 h间隔的ERA5再分析资料，统计分析了华北及周边沿海地区暖季（5—8月）低空急流（LLJ）的特征，并分析了与天气系统相关的低空急流（SLLJ）和边界层急流（BLJ）的形成和日变化机制。结果表明：华北及周边沿海地区5—8月BLJ和SLLJ的发生频率都呈逐月递减态势；BLJ在辽宁、太行山以东地区以及渤海和黄海海面较活跃，SLLJ在内蒙古、辽宁和山东较活跃；BLJ有明显的日变化特征，夜间BLJ的发生频率远高于白天，峰值出现在01时左右。SLLJ的生成与西风槽和西太平洋副热带高压的活动有关，常在西风槽前发生。BLJ的生成受下垫面影响很大，辽宁中北部因其两边高、中间低的“狭管”地形成为BLJ的高发区；夜间边界层湍流摩擦减弱以及非地转风在科氏力作用下的顺时针旋转使夜间边界层风速增大，因此BLJ在夜间多发。

关键词：低空急流天气尺度低空急流边界层急流华北沿海

Abstract：The characteristics of low-level jet（LLJ） over North China and the surrounding coastal areas during the warm season（May to August） of 2008—2023 are statistically analyzed based on the ERA5 reanalysis data at a resolution of 0.25°×0.25°, 1 h interval from the European Centre for Medium-Range Weather Forecasts. The formation and diurnal variation mechanisms of the synoptic system-related low-level jet（SLLJ） and boundary layer jet（BLJ） are discussed. The results show that the occurrence frequencies of both the BLJ and SLLJ in North China and the surrounding coastal areas from May to August show a decreasing trend. The BLJ is more active in Liaoning, east of the Taihang Mountains, and over the Bohai and Yellow Sea surfaces. The SLLJ is more active in Inner Mongolia, Liaoning, and Shandong. The BLJ has obvious diurnal variation, with a much higher occurrence frequency at night than during the day, and its peak occurs around 01:00. The formation of the SLLJ is related to the activities of the westerly trough and Western Pacific subtropical high, and the SLLJ often happens in front of a westerly trough. The formation of the BLJ is greatly affected by the underlying surface: the central and northern part of Liaoning, with its "tube" terrain, high on both sides and low in the middle, becomes a high-frequency area for the BLJ. The weakening of boundary layer turbulence friction and the clockwise rotation of ageostrophic wind under the action of the Coriolis force increase the wind speed in the boundary layer at night, making the BLJ more frequent at night.

Key words：low-level jet; synoptic system-related low-level jet; boundary layer jet; North China; coastal area