“…Recently, studies of nonLambertian re ections and emissions have attracted the interest of more and more researchers (Myneni and Ross 1991, Li et al 1999, Niu et al 2000. With a wide range of scan angles (about ±55°oV-nadir), the eVect of imaging geometry on AVHRR data should be reduced in order to improve the precision of interpretations and classi cations (Paltridge and Mitchell 1990, SouZet et al 1991, Li and Becker 1993, Cihlar et al 1994, Liu et al 1994. For many AVHRR researchers the acquisition of Sun-sensor bidirectional angles for every pixel is critical.…”