11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Wednesday, 5 June 2002
Remote sensing of multilayer cirrus cloud properties during INCA using ATSR-2 data: Case study on 23 March 2000
Albano González, Univ. of La Laguna, La Laguna, Spain; and P. Wendling, B. Mayer, J. F. Gayet, and T. Rother
Poster PDF (295.6 kB)
The analysis of a multilayer cloud system, composed by optically thin cirrus overlaying a lower water cloud, is presented. The in situ measurements of ice crystal volumetric scattering cross sections through a polar nephelometer are utilised to discuss the convenience of using the parameterization proposed by Key et al. (2000) for the single scattering properties of different cirrus particles shapes, simplifying the radiative transfer calculations. This parameterization is compared too with scattering properties for smooth and rough hexagonal columns. In every case the theoretical computations underestimate the backscattering. A new retrieval method using 0.87, 1.6 and 3.7mm channels of dual-view ATSR-2 radiometer is proposed to obtain cirrus properties in these extreme conditions. The variation of the lower cloud is taken into account through its optical thickness, considering that the droplet effective size is correlated with it and assuming a constant temperature. The effects of these assumptions are subsequently estimated. The retrieval scheme is applied to satellite data to compare results with in situ parameters and a good agreement is obtained for that region of the cirrus cloud where a vertical profile of microphysical properties was measured.

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