Multiangle monitoring of atmospheric aerosol and surface reflectance from Mir station

摘要

This paper presents the data of a series of multiangle experiments performed from the orbital station Mir in 1993-1994 over the semiarid regions of Kazakhstan and the forest test sites of Zabaikal'e and Khabarovsky Krai (Russia). Collected data were processed to obtain the optical thickness and scattering function of atmospheric aerosol and surface albedo in ten spectral bands of spectrometer MKS-M2. To this end, the following approach was adopted. In the visible part of the spectrum, where the reflectance of observed surfaces is relatively low, they were assumed to be Lambertian. On this basis, spectral dependencies of the above parameters were obtained using a multiangle method. In the near-infrared (NIR) part of the spectrum, where the surface reflectance is considerable and its anisotropy gives a substantial contribution to the angular dependence of radiance, the optical thickness was obtained via extrapolation from the visible spectral interval and then the effective surface albedo was estimated from measurements. To test the validity of the Lambertian assumption, a qualitative criterion is suggested. Obtained results were also verified by ground albedo measurements: spectral albedo retrieved for the semiarid terrain and the measurements at the subsatellite point coincided with the average accuracy 0.01.