CS-6404: Inverse Modeling Instructor: Adrian Sandu, Computer Science An inverse problem is the task (often encountered in science and engineering) where the model state, or values of some model parameter(s), must be obtained from the observed data. Applications include ocean and atmospheric sciences (find the most likely state given local observations of wind fields, currents, temperatures, etc.), geophysical prospecting (given a signal and an unknown obstacle, what does the obstacle look like?), industrial applications (find the fluid flows from only the boundary measurements), medical diagnosis (find out something about the inside of a body from measurements only taken on the outside), etc. In this class we discuss computational approaches for solving inverse problems. The problem formulation will be developed based on a description of uncertainties. Difficulties like ill-conditioning or non-unique solutions will be highlighted, and regularization techniques will be discussed to alleviate these difficulties. Computational tools discussed include both variational and Monte Carlo approaches. Variational techniques will include an in-depth discussion of numerical optimization methods and adjoint modeling. Monte Carlo approaches include ensemble Kalman and particle filters.