Factors affecting cold-air outbreaks east of the Rocky Mountains
Factors affecting cold-air outbreaks east of the Rocky Mountains
复制标题
影响落基山脉以东冷空气爆发的因素
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
R. Bleck
中科院分区：
文献类型：
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作者：
G. Hartjenstein;R. Bleck
摘要本文用一个两层等熵模式来研究控制落基山脉以东冷空气爆发严重程度的参数，特别是山脉的通道效应。我们仔细研究的案例是1989年2月初的冷空气爆发。研究的参数包括：（a）斜压性，表示为上下层纬向尺度速度的比值;（B）Rossby数;（c）地形高度;（d）冷空气团相对于山脊的初始纵向位置;（e）上层气流中波的存在。研究发现，Rossby数决定了冷空气爆发的强度，而斜压性、地形高度和冷空气团的初始位置则控制着山脉引导冷空气爆发的程度。美国中部上空的上层槽有利于爆发的演变。
Abstract A two-layer isentropic model is used to examine the parameters controlling the severity of cold-air outbreaks east of the Rocky Mountains, and in particular the channeling effect of the mountain range. The case that is scrutinized is the cold-air outbreak of early February 1989. The parameters investigated include (a) the baro-clinicity, expressed as the ratio of upper- to lower-layer zonal scale velocities, (b) the Rossby number; (c) the height of the topography;(d)the initial longitudinal position of the cold air mass relative to the mountain ridge; and (e) the presence of a wave in the upper-level flow. It is found that the Rossby number determines the intensity of a cold-air outbreak, whereas the baroclinicity as well as the height of the orography and the initial position of the cold air mass control the extent to which the outbreak is channeled by the mountain range. An upper-level trough over the central United States favors the evolution of an outbreak.