Using CALIOP to estimate cloud-field base height and its uncertainty: the Cloud Base Altitude Spatial Extrapolator (CBASE) algorithm and dataset

Earth System Science Data

Henderson, David S.^2¹  Mülmenstädt, Johannes^1²  L'Ecuyer, Tristan S.^2³  Sourdeval, Odran^1⁴ 

[1]Institute for Geophysics and Meteorology, Universität zu Köln, Cologne, Germany^3

[2]Institute of Meteorology, Universität Leipzig, Leipzig, Germany^1

[3]Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA^4

[4]University of Wisconsin at Madison, Madison, Wisconsin, USA^2

DOI  :  10.5194/essd-10-2279-2018

学科分类：天文学(综合)

来源: Copernicus Publications

【 摘 要 】

A technique is presented that uses attenuated backscatter profiles from the CALIOP satellite lidar to estimate cloud base heights of lower-troposphere liquid clouds (cloud base height below approximately 3 km ). Even when clouds are thick enough to attenuate the lidar beam (optical thickness τ≳5 ), the technique provides cloud base heights by treating the cloud base height of nearby thinner clouds as representative of the surrounding cloud field. Using ground-based ceilometer data, uncertainty estimates for the cloud base height product at retrieval resolution are derived as a function of various properties of the CALIOP lidar profiles. Evaluation of the predicted cloud base heights and their predicted uncertainty using a second statistically independent ceilometer dataset shows that cloud base heights and uncertainties are biased by less than 10 %. Geographic distributions of cloud base height and its uncertainty are presented. In some regions, the uncertainty is found to be substantially smaller than the 480 m uncertainty assumed in the A-Train surface downwelling longwave estimate, potentially permitting the most uncertain of the radiative fluxes in the climate system to be better constrained.

【 授权许可】

CC BY