云贵高原锋线的动态特征

The moving characteristics of frontal lines on the Yunnan-Guizhou Plateau

中文关键词:  云贵高原锋线  时空特征  动态特征  长持续锋线

英文关键词:Frontal line on the Yunnan-Guizhou Plateau  Spatial-temporal features  Moving characteristics  Long-duration frontal line

中文摘要:

      面向精细化的气象服务需求，为做到对云贵高原锋面系统变化的精准把控，深入认知其动态演变规律，基于50 a（1971—2020年）逐日台站观测资料，提出了一种利用线性拟合近似判定云贵高原地面锋线的方法，并通过综合分析锋线位置和锋线周边气象要素的空间分布和时间变化特征以及长持续锋线事件的锋线位置、走向变化，系统揭示了云贵高原锋线的移动特征，展现了云贵高原准“静”止锋的“动”态特征。结果表明，冷性锋线集中在102.5°—105°E，最大降温区在锋线东侧，暖性锋线集中在104.5°—105.75°E，最大升温区位于锋线西侧；锋线附近气象要素的变化与锋线的移动紧密相关，西进的锋线一般会伴随锋线附近的降温、升压和日照减少，东退的锋线则相反；根据长持续锋线事件的连续演变过程，可将锋线事件区分为静止、西移和东移3类，静止型出现次数最多，西移型可连续快速推进并伴随锋线南部的顺时针摆动，东移型出现频次较低且移速相对较慢。上述结果通过对云贵高原锋线，特别是其动态特征的客观定量描述，为该地区在锋线影响下各气象要素的精细化预报提供了重要参考。

英文摘要:

      A method to approximate the surface frontal line on the Yunnan-Guizhou Plateau by linear fitting is proposed. Through comprehensive analysis of the frontal line position, the spatial distribution and temporal variation of meteorological elements around the frontal line, as well as changes in the position and direction of the frontal line for long-lasting frontal line events, the movement characteristics of the frontal line on the Yunnan-Guizhou Plateau are systematically revealed. The cold (warm) frontal lines are concentrated in 102.5°—105°E (104.5°—105.75°E) and the maximum cooling (heating) zone is located on the eastern (western) side of the frontal line. The changes in meteorological elements around the frontal line are closely related to the movement of the frontal line. The westward moving frontal line usually brings cooling condition, increases surface air pressure, and reduces sunshine hours around the frontal line, while the eastward-moving frontal line often leads to opposite changes. According to the movement of long-lasting frontal line events, frontal line events can be divided into three types: Stationary, westward and eastward. The stationary frontal lines are the most in all the three types. The westward moving frontal line can advance continuously and quickly and is accompanied by a clockwise swing of the frontal line. The eastward moving frontal line has a lower frequency and a relatively low speed. Overall, with the objective and quantitative description of the frontal line, especially its dynamic characteristics, the above results can provide an important reference for the fine forecast of various meteorological elements on the Yunnan-Guizhou Plateau.