Response to Referee # 1 ( Assistant Professor

My main concern is that this paper might not be suitable for Nonlinear Processes in Geophysics. The reason is that the journal emphasizes new methods, applied to realistic problems. The paper simply presents an "old" method applied to a new problem. I find it interesting to read that a particle filter can solve an important and "real" data assimilation, however the general NPG readership might get bored. The authors should decide wether NPG is the best journal to reach the audience they want to reach. This is also reflected by the references, only few of which are to articles in journals similar to NPG. I suspect that this paper would also make a fine contribution in a journal that is more focused on, e.g., Earth system modeling. The authors may want to consider going that route.