We investigate the well-posedness of α-surface quasi-geostrophic (α-SQG) equations in the half-plane, where α = 0 and α = 1 correspond to the 2D Euler and SQG equations respectively. For 0 < α ≤ 1/2, we prove local well-posedness in certain weighted anisotropic Hölder spaces. We also show that such a well-posedness result is sharp: for any 0 < α ≤ 1, we prove nonexistence of Hölder regular solutions (with the Hölder regularity depending on α) for initial data smooth up to the boundary.
The first author was supported by the Samsung Science and Technology Foundation under Project Number SSTF-BA2002-04. The second author was supported by a KIAS Individual Grant (MG086501) at Korea Institute for Advanced Study. The third author was partially supported by the NUS startup grant A-0008382-00-00, MOE Tier 1 grant A-0008491-00-00, and the Asian Young Scientist Fellowship.