【记录】CALIPSO Lidar数据相关随时mark一下子

目录

 

1. Lidar Level 1B数据相关介绍

2. Lidar Level 2 Cloud and Aerosol Layer数据相关介绍

3. 532nm & 地表

4. FAQ

1）Why can't I find lidar (CALIOP) data over a specific location? Is the order tool broken?

2）What are the fill values? Are they the same in every file/every variable?

3）Is CALIOP data quality homogeneous over the whole Earth?

4）Why are there negative attenuated backscatter values in the L1 lidar data? (Aren't these values completely non-physical???) Are these negative values removed before calculating the Level 2 Column Integrated Backscatter?

更新日期

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1. Lidar Level 1B数据相关介绍

https://www-calipso.larc.nasa.gov/resources/calipso_users_guide/data_summaries/l1b/index.php#Table01

2. Lidar Level 2 Cloud and Aerosol Layer数据相关介绍

https://www-calipso.larc.nasa.gov/resources/calipso_users_guide/data_summaries/layer/index.php

• Opacity_Flag：表征激光是否穿透的参数；
• NumberLayers_Found：探测到的云层数；
• Column_Optical_Depth_Aerosols_532：气溶胶层光学厚度；
• Column_Optical_Depth_Cloud_532：云层光学厚度。

3. 532nm & 地表

https://www-calipso.larc.nasa.gov/products/lidar/browse_images/production/

CALIOP 532纳米通道不能从非常强的回波(如海洋和陆地表面的回波)中立即恢复。相反，有一个近似指数的衰减。

由于这种效应，地表下经常有明显的激光雷达回波。这种影响在南极洲尤其明显，那里频繁的无云大气和高反射表面导致表面信号明显延伸到真实表面以下。

当大气不清晰时，变化的大气衰减将调节地面返回的强度和瞬时恢复的幅度。来自非常强散射云的返回信号也能产生这种效果，尽管并不总是很明显。

The CALIOP 532 nm channels do not recover instantaneously from very strong returns such as those from ocean and land surfaces. Instead, there is a decay which is approximately exponential.

Due to this effect, there is often apparent lidar return from beneath the surface. This effect is particularly noticeable in Antarctica where frequent cloud-free atmospheres and a highly reflective surface result in surface signals which apparently extend significantly below the true surface.

When the atmosphere is not clear, varying atmospheric attenuation will modulate the strength of the surface return and the magnitude of the transient recovery. Return signals from very strongly scattering clouds can also produce this effect, although it is not always apparent.

4. FAQ

https://www-calipso.larc.nasa.gov/resources/calipso_users_guide/faq.php