Systematic observation of westward propagating cloud bands over the Arabian Sea during Indian Ocean Experiment (INDOEX) from Meteosat‐5 data
Systematic observation of westward propagating cloud bands over the Arabian Sea during Indian Ocean Experiment (INDOEX) from Meteosat‐5 data
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印度洋实验 (INDOEX) 期间利用 Meteosat-5 数据系统观测阿拉伯海上空向西传播的云带
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发表时间：
2003
期刊：
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通讯作者：
M. Desbois
中科院分区：
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作者：
F. Désalmand;A. Szantai;L. Picon;M. Desbois
[1]在印度洋实验的实地实验阶段，观测到平行于西印度海岸并向西传播的线状云。气象卫星5号图像用于描述这些事件的生命周期。在1999年旱季的四个时期（1999年1月15日、2月16日至19日、2月27日至3月7日和4月1日至3日），每天都观测到单云带，或主云带，然后是（多达10条）波浪状的次级平行云线。在这四个时段中，每天晚上都会产生一条云带或一组云带。它们的长度达到数百公里，宽度低于40公里，在某些情况下持续时间超过24小时。在领先云线后面观察到的较小云线较窄，相隔2-10公里。云顶温度比阿拉伯海低3-8°C，相当于夜间海拔500 - 1200米，白天低于2500米。云带以每秒13米左右的速度向西穿越阿拉伯海，比在周围地区测得的风速还要大。云带的运动与大气现象的波浪式传播相似，例如澳大利亚的牵牛花。不同情况的共同要素如下：当云带出现时，印度西南海岸附近的弱低空风，印度西北海岸附近的风具有偏北分量，西印度海岸沿着存在海陆风环流，以及阿拉伯海东北部存在高浓度污染物。然而，这些元素之间的现有物理链接（如果有的话）仍然需要调查。
[1] During the field experiment phase of the Indian Ocean Experiment (INDOEX), linear cloud formations parallel to the West Indian coast and propagating westward have been observed. Meteosat-5 images are used for the description of the life cycle of these events. Single cloud bands, or main cloud bands followed by (up to 10) secondary parallel cloud lines with a wavelike pattern, have been observed daily during four periods in the dry season of 1999 (15 January, 16–19 February, 27 February to 7 March, and 1–3 April 1999). During these four periods, one single cloud band or a packet of cloud bands is generated every day at nighttime. Their length reaches several hundreds of kilometers, their width lies below 40 km, and their duration in some cases exceeds 24 hours. The smaller cloud lines observed behind the leading cloud line are narrower and are separated by a distance of 2–10 km. Cloud tops are about 3–8°C colder than the Arabian Sea, corresponding to an altitude between 500 and 1200 m during the night and below 2500 m during daytime. Cloud bands travel westward over the Arabian Sea at a speed around 13 m/s, greater than the wind speed measured in the surrounding area. The motion of the cloud band presents similarities with the wavelike propagation of atmospheric phenomena such as the Australian morning glories. Common elements to the different cases are the following: weak low-level winds close to the southwestern Indian coast when the cloud bands appear, winds with a northerly component in the vicinity of the northwestern Indian coast, the presence of a sea-land breeze circulation along the West Indian coast, and the presence of high concentrations of pollutants over the northeastern Arabian Sea. However, existing physical links between these elements (if any) still have to be investigated.