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Retrieving the Polar Mixed‐Phase Cloud Liquid Water Path by Combining CALIOP and IIR Measurements
Author(s) -
Luo Tao,
Wang Zhien,
Li Xuebin,
Deng Shumei,
Huang Yong,
Wang Yingjian
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd027291
Subject(s) - liquid water path , lidar , environmental science , remote sensing , cloud height , cloud top , mean squared error , meteorology , cloud computing , aerosol , statistics , computer science , mathematics , physics , geology , cloud cover , operating system
Mixed‐phase cloud (MC) is the dominant cloud type over the polar region, and there are challenging conditions for remote sensing and in situ measurements. In this study, a new methodology of retrieving the stratiform MC liquid water path (LWP) by combining Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) and infrared imaging radiometer (IIR) measurements was developed and evaluated. This new methodology takes the advantage of reliable cloud‐phase discrimination by combining lidar and radar measurements. An improved multiple‐scattering effect correction method for lidar signals was implemented to provide reliable cloud extinction near cloud top. Then with the adiabatic cloud assumption, the MC LWP can be retrieved by a lookup‐table‐based method. Simulations with error‐free inputs showed that the mean bias and the root mean squared error of the LWP derived from the new method are −0.23 ± 2.63 g/m 2 , with the mean absolute relative error of ~4%. Simulations with erroneous inputs suggested that the new methodology could provide reliable retrieval of LWP to support the statistical or climatology analysis. Two‐month A‐train satellite retrievals over Arctic region showed that the new method can produce very similar cloud top temperature (CTT) dependence of LWP to the ground‐based microwave radiometer measurements, with a bias of −0.78 g/m 2 and a correlation coefficient of 0.95 between the two mean CTT‐LWP relationships. The new approach can also produce reasonable pattern and value of LWP in spatial distribution over the Arctic region.