| 双雨带过程中的回流暖区暴雨个例对比研究 |
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| 引用本文： | 林确略,赵华生,林宝亭.双雨带过程中的回流暖区暴雨个例对比研究[J].热带气象学报,2020,36(6):721-733. |
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| 作者姓名： | 林确略 赵华生 林宝亭 |
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| 作者单位： | 1.玉林市气象局，广西 玉林 537000 |
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| 基金项目： | 中国气象局预报员专项项目CMAYBY2015-057广西自然科学基金项目2018JJA150083广西壮族自治区气象局气象科研项目桂气科2019M17 |
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| 摘 要： | 利用常规观测资料、NCEP 1 °×1 °FNL资料、自动站降水资料，对华南两次双雨带过程中的回流暖区暴雨个例进行了对比分析，结果表明:(1)与暖湿的南到西南气流相比，变性高压脊后部回流的东到东南气流具有一定干冷属性，边界层两支不同性质的气流汇合形成辐合渐近线和边界层锋区。回流暖区暴雨实际是先有回流、预先在东侧形成浅薄的冷池，后有高空槽加深东移、带来边界层西南风，与东南风辐合，形成低层辐合抬升条件，西南风暖平流使边界层锋区加强并缓慢东移，产生的暴雨。回流和高空槽均起到关键的作用；(2)回流暖区暴雨区域在边界层内具有弱对流性不稳定或湿中性层结、而在中低层具有明显对流性不稳定，其发生发展机制有别于锋前暖区暴雨和典型锋面暴雨；(3)边界层较大水平螺旋度与回流暖区暴雨有良好对应关系，对回流暖区暴雨预报有指示意义，是回流暖区暴雨区别于锋面暴雨的重要动力学特征；(4)回流暖区的水汽输送主要集中在850 hPa以下，以925 hPa最显著，北侧锋区的水汽输送主要集中在850~700 hPa；南北两支雨带低层的水汽输送通道可能存在部分重合，当南侧暖区雨带的对流发展起来后，部分水汽可能被南侧辐合系统截留，从而影响北侧的水汽输送强度。这可能是导致北雨带降雨强度不如南雨带的一个原因。
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| 关 键 词： | 华南 双雨带 回流 暖区暴雨 辐合渐近线 水平螺旋度 |
| 收稿时间： | 2020-01-03 |
ANCOMPARATIVE ANALYSIS ON BACKFLOW WARM-SECTOR RAINSTORM CASES IN DOUBLE RAIN BELTS PROCESS |
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| LIN Que-lue,ZHAO Hua-sheng,LIN Bao-ting.ANCOMPARATIVE ANALYSIS ON BACKFLOW WARM-SECTOR RAINSTORM CASES IN DOUBLE RAIN BELTS PROCESS[J].Journal of Tropical Meteorology,2020,36(6):721-733. |
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| Authors: | LIN Que-lue ZHAO Hua-sheng LIN Bao-ting |
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| Institution: | 1.Yulin Meteorological Bureau, Yulin 537000, China2.Institute of Meteorological Sciences of Guangxi, Nanning 530022, China |
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| Abstract: | By using routine observational data, 1 °×1 ° FNL data from the NCEP and precipitation data from Chinese automatic weather stations, the present study compared two typical cases of backflow warm-sector rainstorm in double rain belts process occurred in south China. The results were as follows. (1) Compared with warm and wet south to southwestern airflow, the southeastern airflow from the back of the denatured high-pressure ridge was dry and cold. Two different airflows on the boundary layer converged and formed convergence asymptote and mesoscale frontal zone. First, there was reflux, and a shallow cold pad was formed in the east; then, the high trough deepened and moved eastward, bringing with it southwestern wind of boundary layer and converging with southeastern wind, forming conditions for convergence and uplift of lower layer. Due to the warm advection of southwest wind, the boundary layer front developed and moved eastward slowly. Then the backflow warm-sector rainstorm occurred. Therefore, both backflow and high trough played a key role. (2) At the warm-sector rainstorm area, there were weak convective instability or wet neutral stratification in boundary layers, and obvious convective instability in low to middle layers. This formation mechanism was distinguished from warm-sector rainstorm ahead of fronts and typical frontal rainstorm. (3) Larger horizontal helicity on boundary layer indicated back-flow warm-sector rainstorm, and it was important dynamic characteristics which distinguished back-flow warm-sector rainstorm from frontal rainstorm. (4) On backflow warm-sector area, vapor transport was mainly concentrated below the layer of 850 hPa and was most significant on the layer of 925 hPa. On frontal area, vapor transport was mainly concentrated on the layer of 850~700 hPa. There might be some overlap of water vapor transport channels on the lower layer of two rain belts in north and south. When the convection of the southern rain belt in the warm zone developed, partial vapor might be intercepted by the southern convergence system. Thus, vapor transport intensity in the north might be affected. This might be one of the reasons why the rainfall intensity of the north rain belt was not as strong as that of the south. |
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| Keywords: | south China double rain belts backflow warm-sector rainstorm convergence asymptote horizontal helicity |
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