Upper‐tropospheric relative humidity observations and implications for cirrus ice nucleation
Upper‐tropospheric relative humidity observations and implications for cirrus ice nucleation
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DOI：
10.1029/98gl01089
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发表时间：
1998-05
影响因子：
5.2
通讯作者：
A. Heymsfield;L. Miloshevich;C. Twohy;G. Sachse;S. Oltmans
中科院分区：
文献类型：
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作者：
A. Heymsfield;L. Miloshevich;C. Twohy;G. Sachse;S. Oltmans
在地形波云和卷云环境中获得的相对湿度（RH）测量值用于研究对流层上部冰晶成核所需的随温度变化的RH，RHnuc（T）。高冰-在晴朗的空气中的过饱和度-有利于维持飞机的尾迹，但低于RHnuc，因此不足以形成卷云-并不罕见。早期的研究结果支持中纬度大陆环境中的RHnuc从温度高于−39°C的水饱和度下降到−55°C的75%RH。在-55 °C以下测定RHnuc的不确定性部分来自微物理仪器的尺寸检测限制，但对SUCCESS实验数据的分析表明，-55 °C以下的RHnuc在70%至88%之间。在海岸外获得的少量数据表明，RHnuc也可能取决于气溶胶的性质。
Relative humidity (RH) measurements acquired in orographic wave cloud and cirrus environments are used to investigate the temperature‐dependent RH required to nucleate ice crystals in the upper troposphere, RHnuc(T). High ice‐supersaturations in clear air—conducive to the maintenance of aircraft contrails yet below RHnuc and therefore insufficient for cirrus formation—are not uncommon. Earlier findings are supported that RHnuc in mid‐latitude, continental environments decreases from water‐saturation at temperatures above −39°C to 75% RH at −55°C. Uncertainty in determining RHnuc below −55°C results in part from size detection limitations of the microphysical instrumentation, but analysis of data from the SUCCESS experiment indicates that RHnuc below −55°C is between 70 and 88%. A small amount of data acquired off‐shore suggests the possibility that RHnuc may also depend on properties of the aerosols.