Cumulus Heating and CISK in the Extratropical Atmosphere. Part I: Polar Lows and Comma Clouds
Cumulus Heating and CISK in the Extratropical Atmosphere. Part I: Polar Lows and Comma Clouds
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温带大气中的积云加热和 CISK。
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
Han‐Ru Cho
中科院分区：
文献类型：
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作者：
G. Craig;Han‐Ru Cho
摘要 将斜压不稳定性Eady模型与波动CISK相结合，探讨温带地区积云加热的影响和CISK的可能性。对于静止状态的扰动，没有内在的时间尺度，但是可以通过求解方程来求解位势趋势。研究发现，除非加热超过阈值，否则 CISK 扰动不会增长。当边界层含水量增加、静稳定性降低或对流层中热量分布较低时，该值会减小。对于小加热速率，斜压基本态的扰动类似于斜压波，加热主要用于降低有效静态稳定性，从而导致更快的生长和更短的波长。然而，随着加热的增加，不稳定性逐渐呈现出纯CISK扰动的特征。转换级别显示出与 CISK c 中的阈值相同的模型参数依赖性...
Abstract The effects of cumulus heating and the possibility of CISK in extratropical latitudes are explored by combining the Eady model of baroclinic instability with wave-CISK. For perturbations about a state of rest, there is no intrinsic time scale, however the equations can be solved for geopotential tendency. It was found that CISK disturbances could not grow unless the heating exceeded a threshold value. This value is reduced when the boundary layer moisture content is increased, the static stability decreased, or the heating distributed lower in the troposphere. Perturbations about a baroclinic basic state, for small heating rates resemble a baroclinic wave with heating acting mainly to reduce the effective static stability, resulting in faster growth and shorter wavelengths. However, as the heating is increased, the instability gradually takes on the characteristics of the pure CISK disturbance. The transition level shows the same dependencies on model parameters as for the threshold in the CISK c...