A new multispectral cloud retrieval method for ship-based solar transmissivity measurements

Within the German Leibniz‐network OCEANET project, ship‐based lidar and microwave remote sensing as well as spectral zenith radiance observations with the COmpact RAdiation measurements System (CORAS) were performed. During three cruises latitudes between 50°N and 50°S were covered. A new spectral r...

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Bibliographic Details
Published in:Journal of geophysical research. Atmospheres 2014-10, Vol.119 (19), p.11,338-11,354
Main Authors: Brückner, M., Pospichal, B., Macke, A., Wendisch, M.
Format: Article
Language:English
Subjects:
Boundary layers
Cirrus clouds
cloud retrieval
Clouds
Droplets
Geophysics
Ice
Lidar
Meteorological satellites
microphysical properties
Radiation measurement
radiative transfer
Remote sensing
Retrieval
Spectra
spectral transmissivity
Transmissivity
Water
Wavelengths
Zenith
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Summary:Within the German Leibniz‐network OCEANET project, ship‐based lidar and microwave remote sensing as well as spectral zenith radiance observations with the COmpact RAdiation measurements System (CORAS) were performed. During three cruises latitudes between 50°N and 50°S were covered. A new spectral retrieval method to derive the cloud optical thickness τ and the droplet effective radius reff using CORAS measurements is developed. The method matches CORAS measurements of ratios of spectral transmissivity at six wavelengths with modeled transmissivities. This retrieval is fast and accurate and thus suitable for operational purposes. The new approach circumvents ambiguities of existing cloud retrievals and reduces the influence of measurement uncertainties. It is applied to homogenous and heterogeneous liquid water and cirrus clouds. In boundary layer liquid water clouds, the retrieved effective radius was more variable, whereas in the cirrus it was rather constant. Furthermore, the liquid water path LWP was derived and compared to data from a microwave radiometer. The new retrieval tends to overestimate LWP for thick liquid water clouds but slightly underestimate LWP for thin clouds. The presented method cannot be applied to mixed‐phase clouds. The maximum retrieval of τ and reff for liquid water clouds is 80 in τ and 30 μm in reff, respectively; for cirrus clouds the limitations of the retrieval are 10 in τ and 60 μm in reff. Key Points Microphysical cloud properties are retrieved with a multispectral retrievalSpectral zenith transmissivity of clouds is characterizedLiquid water clouds and ice clouds are characterized
ISSN:2169-897X
2169-8996
DOI:10.1002/2014JD021775