On the horizontal and temporal structure of noctilucent clouds as observed by satellite and lidar at ALOMAR (69N)
On the horizontal and temporal structure of noctilucent clouds as observed by satellite and lidar at ALOMAR (69N)
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ALOMAR（69N）卫星和激光雷达观测到的夜光云的水平和时间结构
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发表时间：
2012
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通讯作者：
Gary E. Thomas
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作者：
G. Baumgarten;Amal Chandran;J. Fiedler;Peter Hoffmann;N. Kaifler;J. Lumpe;A. Merkel;C. Randall;D. Rusch;Gary E. Thomas
分别从地面和空间对挪威北部(69°N，16°E)Alomar考察站上空的夜光云(NLC)和极地中层云(PMC)进行了同步和共同的体积观测。2008年8月5日的一个详细案例研究表明，测量的颗粒大小和光学性质的T矩阵模拟允许将这两种观测技术结合起来。从地面上，通过激光雷达探测相隔约40公里的两个位置的云的时间演变，在重合之前、期间和之后进行了观测。从太空中，AIM卫星上的CIPS仪器观测到了云层的水平结构。利用阿洛马站的中层雷达测风资料，计算了云粒子的平流，并将地面观测到的云的时间演变与卫星观测到的水平结构进行了比较。通过这种比较，可以估计云在多长时间内充当被动示踪器。我们发现，在这个事例研究中，大于约5公里×5公里的云结构和慢于约1分钟的振荡表现为与约300公里的水平尺度相对应的长达1小时的被动示踪物。然而，如果云层显示出亮度调制为20%的波动结构，微物理变化可能在分钟和公里的尺度上发生。
Simultaneous and common volume observations of Noctilucent Clouds (NLC) and Polar Mesospheric Clouds (PMC) have been performed above the ALOMAR research station in Northern Norway (69°N, 16°E) from ground and space, respectively. A detailed case study on August 5, 2008 shows that the measured particle sizes and T‐matrix simulations of the optical properties allow to combine the two observation techniques. From the ground, the observations were performed by lidar sounding of the temporal evolution of the cloud at two locations separated by about 40 km, before, during and after the coincidence. From space, the CIPS instrument onboard the AIM satellite observed the horizontal structure of the cloud. Using mesospheric radar wind measurements at ALOMAR the advection of the cloud particles is calculated and the temporal evolution of the cloud as seen from ground is compared with the horizontal structure observed from satellite. This comparison allows estimation of the timescales during which the clouds behave as passive tracers. We find that during this case study cloud structures larger than about 5 km × 5 km and oscillations slower than about one minute behaved like a passive tracer for up to one hour corresponding to horizontal scales of about 300 km. However, if the cloud shows wave structures with brightness modulations of 20% microphysical changes might take place on scales of minutes and kilometers.