Compare with the reflectance of land surface, ocean water is much less. And, the contribution of atmospheric molecules and aerosols plays an vital importance on the water-leaving reflectance inversion. In order to simplify the inversion process, we generate a look-up-table(LUT) that contains the observation geometry information, the aerosol optical depth(AOD), the exponent of Junge power law(V) and the other factors used to calculate the water-leaving reflectance. The AOD and V are determined using our previous iterative algorithm from dual near-infrared(NIR) and dual shortwave infrared( SWIR) channels, respectively. We compare the retrieved AOD and V with Aerosol Robotic Network(AERONET) measurement data to ensure the precision of aerosol information. The AERONET AOD at 550nm is 0.0876, and the inversed AOD from dual-NIR and dual-SWIR is 0.05-0.325 and 0.0373-0.98, respectively. For dual- NIR, there are 31.97% and 57.18% pixels with the AOD absolute relative error less than 10% and 20%, respectively. For dual-SWIR, there are 31.01% and 59.79%. Then, we use the retrieved aerosol information together with the observation geometry information to get the factors used to calculate the water-leaving reflectance through interpolation. Finally, we use the MODIS ocean color product to verify the water leaving reflectance calculated based on aerosol retrieved from NIR and SWIR, and the two calculated water-leaving reflectance are marked as ρNIR and ρSWIR. In the visible and near-infrared region, both of them are smaller than the product values. Despite the ρSWIR is larger than ρNIR, the overcorrection is much more serious in ρNIR.
An iterative algorithm is used to simultaneously determining the aerosol optical thickness(AOT) and the exponent of Junge power-law from AATSR L1B reflectance data of channel 0.87um and 1.61um over Taiwan Strait, in this paper. Considering the variation of aerosol complex refractive index(ACRI) with wavelength, the retrieval of aerosol is implemented under constant and variable ACRI. Suppose the MODIS aerosol product values are accurate. For constant ACRI, there are 47.87% and 96.96% pixels with acceptable retrieval AOT and the exponent of Junge power law value, respectively. Likewise, there are 61.02% and 67.01% pixels for variable ACRI. Compared with the retrieval error under constant ACRI, there are 91.79% and 8.3% pixels with smaller AOT and Junge power-law index retrieval error under variable ACRI, respectively. Besides, the precision of AOD retrieved under constant ACRI is equivalent with variable ACRI when AOT product is less than 0.3. However, both constant and variable ACRI can obtain consistent spatial and temporal distribution of AOT.