upper-level trough

基本解释

They form in the upper-level trough, in the left side of the lower-level jet, and in the surface pre-frontal area.
它们发生在高空小槽底部，低空偏南风急流左侧和地面冷峰西端的南侧或准静止锋上的暧湿辐合区中。
qk.cams.cma.gov.cn
The main influencing weather systems are: upper-level westerly trough, southern branch trough, subtropical jet, strong low-level southwest jet and quasi-stationary shear line.
高空西风槽和南支槽及其前侧的副热带急流和低空强西南气流及准静止切变线是诱发福建省春季冰雹最主要的天气系统。
Through the analysis, it is shown that the Matsa s extratropical transition and the re-intensification are due to the intrusion of cold air from the upper-level trough into the typhoons circulation.
以一个在陆上长久维持并最终演变成温带气旋的登陆台风“麦莎”为研究对象，通过对其北上变性过程的分析发现，台风与中高纬西风槽的相互作用使得冷空气侵入是其变性加强的原因。