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Cloud optical and microphysical properties derived from ground‐based and satellite sensors over a site in the Yangtze Delta region
Author(s) -
Liu Jianjun,
Li Zhanqing,
Zheng Youfei,
Chiu J. Christine,
Zhao Fengsheng,
Cadeddu Maria,
Weng Fuzhong,
Cribb Maureen
Publication year - 2013
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/jgrd.50648
Subject(s) - environmental science , moderate resolution imaging spectroradiometer , liquid water path , radiance , satellite , spectroradiometer , radiometer , remote sensing , effective radius , atmospheric sciences , zenith , meteorology , visible infrared imaging radiometer suite , optical depth , geography , aerosol , reflectivity , physics , quantum mechanics , astronomy , galaxy , optics
Comprehensive surface‐based retrievals of cloud optical and microphysical properties were made at Taihu, a highly polluted site in the central Yangtze Delta region, during a research campaign from May 2008 to December 2009. Cloud optical depth (COD), effective radius (R e ), and liquid water path (LWP) were retrieved from measurements made with a suite of ground‐based and spaceborne instruments, including an Analytical Spectral Devices spectroradiometer, a multifilter rotating shadowband radiometer, a multichannel microwave radiometer profiler, and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua satellites. Retrievals from zenith radiance measurements capture better the temporal variation of cloud properties than do retrievals from hemispherical fluxes. Annual mean LWP, COD, and R e are 115.8 ± 90.8 g/m 2 , 28.5 ± 19.2, and 6.9 ± 4.2 µm. Over 90% of LWP values are less than 250 g/m 2 . Most of the COD values (>90%) fall between 5 and 60, and ~80% of R e values are less than 10 µm. Maximum (minimum) values of LWP and R e occur in summer (winter); COD is highest in winter and spring. Raining and nonraining clouds have significant differences in LWP, COD, and R e . Rainfall frequency is best correlated with LWP, followed by COD and R e . Cloud properties retrieved from multiple ground‐based instruments are also compared with those from satellite retrievals. On average, relative to surface retrievals, mean differences of satellite retrievals in cloud LWP, COD, and R e were −33.6 g/m 2 (−26.4%), −5.8 (−31.4%), and 2.9 µm (29.3%) for 11 MODIS‐Terra overpasses and −43.3 g/m 2 (−22.3%), −3.0 (−10.0%), and −1.3 µm (−12.0%) for 8 MODIS‐Aqua overpasses, respectively. These discrepancies indicate that MODIS cloud products still suffer from large uncertainties in this region.