Tuesday, 16 January 2007
A methodology study of estimating ice cloud geometrical thickness from satellite infrared and visible measurements
Exhibit Hall C (Henry B. Gonzalez Convention Center)
The previous sensitivity study has shown that infrared algorithm used for retrieving cloud optical thickness (τ) and effective particle size (De) is much sensitive to cloud geometrical thickness while the algorithm based on solar reflectance is not. On the basis of this, in present study we have developed an algorithm to estimate cloud geometrical thickness using the combined measurements from the brightness temperatures of the Moderate Resolution Imaging Spectroradiometer (MODIS) infrared bands at 8.5 and 11 μm (or 12 μm) and the solar reflectance at 0.65 and 1.64 μm (or 2.13 μm). The pre-computed lookup libraries of the solar reflectance are used to retrieve τ and De first. Then the cloud geometrical thickness can be derived by minimizing the brightness temperature difference between the measured and simulated, which is conducted with the retrieved τ and De from solar reflectance and assumed cloud geometrical thicknesses.