Seasonal and Diurnal Changes in Cirrus Clouds as Seen in Four Years of Observations with the VAS
Seasonal and Diurnal Changes in Cirrus Clouds as Seen in Four Years of Observations with the VAS
复制标题
VAS 四年观测中看到的卷云的季节和日变化
DOI：
10.1175/1520-0450(1992)031
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
K. Strabala
中科院分区：
文献类型：
--
作者：
W. Menzel;D. Wylie;K. Strabala
在过去的4年里，GOES VAS在15 μm二氧化碳吸收带的多光谱观测一直被用来编制美国大陆的云量统计。CO2技术计算云顶压力和有效发射率，并可靠地区分透明卷云和不透明云。透明卷云的出现频率呈现出很小的季节性变化，在所有季节中，它们通常有25%-30%的时间出现。对流云的日变化与落基山脉和美国东南部对流的日变化相对应，在对流云活动之后，卷云的日变化增加了20%。在冬季的几个月里，没有发现透明卷云的日变化。将卷云与一些常见的大气特征联系起来的尝试表明，大多数卷云发生在动力学参数表明垂直运动上升的地方，但这并不意味着卷云的形成。
Abstract GOES VAS multispectral observations in the carbon dioxide absorption band at 15 μm have been used to compile cloud-cover statistics over the continental United States for the past 4 years. The CO2 technique calculates both cloud-top pressures and effective emissivities and reliably distinguishes semitransparent cirrus from opaque clouds. The frequency of semitransparent cirrus clouds exhibits small seasonal variation; they are generally present 25%–30% of the time in all seasons. Diurnal variations of semitransparent cirrus are found only in the summer months and correspond to diurnal variations in convection in the Rocky Mountains and southeastern United States, increases of 20% in cirrus are noted subsequent to the convective cloud activity. In the winter months, no diurnal change in semitransparent cirrus is detected. Attempts to correlate cirrus with some common atmospheric features reveal that a majority of cirrus occurred where dynamic parameters indicate rising vertical motion but that con...