from Two-layer Rough Surfaces Peng XU 1 , Leung TSANG 2 , Kun-Shan CHEN 3 1. School of Electronic Information, Wuhan University, Wuhan 430079, China; 2. Department of Electrical Engineering, University of Washington, Seattle, WA 98195, USA; 3. Center for Space and Remote Sensing, National Central University, Chung-Li 32054, Taiwan ABSTRACT It is shown in our previously published results that the large fourth Stokes parameter can be created from a rough surface over multi-layered media. In this paper we consider the four Stokes parameters in microwave emission from two-layer rough surfaces. The rough surfaces vary in one horizontal direction so that azimuthal asymmetry exists in the 3-D problem. Periodic boundary conditions are used. The numerical results show that the two-layer periodic rough surfaces can also reduce the vertical and horizontal brightness temperatures remarkably. The interactions between the two rough surfaces also enhance the third and fourth Stokes parameters. In particular, the fourth Stokes parameter can be larger than previous layered structure. The results presented in this paper are compared with the previously published results from a rough surface over multi-layered media, the new structure can remove the large valleys in the vertical and horizontal brightness temperatures from the former sastrugi structure. It is found that the reasons resulting in the large fourth Stokes parameter are not interfaces乫 shapes below the first rough surface but the first rough surface乫s shape and relative magnitude of permittivities of region 1 and 2, all cases with the large fourth Stokes parameter should satisfy ε2 ε1 due to total internal reflection from layers.