Enhancement of the consistency of MODIS thin cirrus with cloud phase by adding 1.6 µm reflectance
Abstract:Optically thin cirrus derived from the Moderate‐resolution Imaging Spectroradiometer (MODIS) instrument is examined in connection with its cloud phase (ice crystal or liquid droplet) for quasi‐single layer thin cirrus (either single‐layer thin cirrus or thin cirrus overlying low‐level thin clouds) over water surface conditions. Analysing 142 MODIS data samples during the period 1–16 March 2000, it is found that only about 20% of MODIS thin cirrus having a total‐column cloud optical depth less than 2.0 was detected as ice phase. In the present study, MODIS cloud phase datasets are newly reproduced by adding the 1.6 µm reflectance to an existing infrared trispectral algorithm of MODIS which used the 8.7, 11 and 12 µm bands. The percentage of ice phase in the thin cirrus is estimated at about 80% when new cloud phase is incorporated. The increase is found for all regions, in particular in mid‐latitudes.
Document Type: Research Article
Affiliations: 1: School of Earth and Environmental Sciences, Seoul National University, Seoul 151‐742, Korea 2: Meteorological Research Institute, Korea Meteorological Administration, Seoul, Korea 3: Department of Satellite Information Science, Pukyong National University, Busan, Korea
Publication date: November 10, 2005