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首页> 外文会议>International Laser Radar Conference >CLOUD BACKSCATTER PHASE FUNCTION AND EMITTANCE OF LOW AND MIDLEVEL CLOUDS FROM LIRAD-TYPE MEASUREMENTS FROM CALIPSO
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CLOUD BACKSCATTER PHASE FUNCTION AND EMITTANCE OF LOW AND MIDLEVEL CLOUDS FROM LIRAD-TYPE MEASUREMENTS FROM CALIPSO

机译：来自Calipso的Lirad型测量的Lirrad型测量的云反向散射阶段功能和低音云的磁阻

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Lidar/Radiometer (LIRAD) observations from the ground have yielded values of the cloud backscatter-to-extinction ratio and emittance of midlevel and boundary layer clouds, as well as of the more common cirrus observations. The cloud backscatter-to-extinction ratio is numerically equal to the cloud particle backscatter phase function, when suitably normalised. CALIPSO will be launched in early 2005 and will carry a two-wavelength depolarisation lidar together with a scanning infrared filter radiometer. Thus CALIPSO is ideal for LIRAD-type observations. Although midlevel and boundary layer water clouds tend to have higher optical depths than cirrus clouds, LIRAD observations of midlevel clouds and boundary layer clouds indicate that cases of semitransparent water clouds do occur. The backscatter phase function of water clouds is also much more constant than that for ice clouds. Theoretical studies indicate that the total variation of backscatter phase function in water clouds is about +- 5%. An advantage of this small variation is that the integrated backscatter can be used also for calibration of the lidar instrument or, alternatively, estimation of the multiple scattering factor in the backscatter. An inherent difficulty in observations of water clouds is that the typical cellular nature of stratocumulus and altocumulus clouds implies that the field of view of the lidar may not be cloud-filled at any one time. Thus a signal from an unfilled field of view could be confused with that from a cloud of lower optical depth. Further, the field of view of the infrared radiometer is different from that of the lidar. In order to calibrate the lidar, a cloud-filled field of view is required. These issues are explored in this paper and a method for separating the two cases is presented.
机译：LIDAR /辐射计（Lirad）从地面的观察结果产生了云反向散射与消光比和中际和边界层云的发射率的值，以及更常见的卷曲观测。云反向散射到消光比在适当归一化的情况下数值等于云粒子后散射阶段功能。 CALIPSO将于2005年初推出，并将与扫描红外滤光片仪一起携带双波长Depolarisation LIDAR。因此，Calipso是Lirad型观测的理想选择。虽然米德尔和边界层水云往往具有比Cirrus云更高的光学深度，但Lirad对Midlevel云和边界层云的观察表明发生半透明水云的情况。水云的后散射阶段功能也比冰云更加恒定。理论研究表明，水云中反向散射阶段功能的总变化约为±5％。这种小变化的优点是集成的反向散射也可以用于校准LIDAR仪器，或者可选地，估计反向散射中的多个散射因子。观察水云的固有难度是划分阶段和长高腔云的典型细胞性质意味着延迟雷达的视野可能不会在任何时候填充云。因此，来自未填充视野的信号可能与从较低光深的云混淆。此外，红外辐射计的视野与激光雷达的视野不同。为了校准LIDAR，需要云填充的视野。本文探讨了这些问题，并提出了一种分离两种情况的方法。

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