Experimental Approach of Reflectance Based Vicarious Calibration Method for Solar Reflectance Wavelength Region of Sensor Onboard Remote Sensing Satellites

Experimental approach of reflectance based vicarious calibration of solar reflectance wavelength region of mission instruments onboard remote sensing satellites is conducted. As an example, vicarious calibration of ASTER/VNIR with estimated aerosol refractive index and size distribution that depends on atmospheric conditions is discussed. Strange solution of estimated refractive index and size distribution may occurred due to the fact that solution fell into one of local minima in the inversion process for phase function fitting between measured and estimated with assumed refractive index and size distribution. This paper describes atmospheric conditions that may induce such a situation. Namely, it may occur when the atmospheric optical depth is too thin and or Junge parameter is too small. In such case, refractive index and size distribution estimation accuracy is poor. A relation between refractive index and size distribution estimation accuracy and estimation accuracy of the Top of the Atmosphere (TOA) radiance (vicarious calibration accuracy) is also clarified in particular for ASTER/VNIR vicarious calibration. It is found that 10% of the refractive index and size distribution estimation error causes approximately 1.3% of TOA radiance estimation error. Keywords—Vicarious calibration; Top of Atmosphere Radiance, At sensor Radiance; refractive index; size distribution; Junge parameter; optical depth