An update on the 4DLETKF data assimilation system for

filter4dEnsemble Kalman filteringwas developed as away to assimilate observed data to track the current state in a computational model. In this paper we showthat the ensemble approach makesTable-top filters can remove contaminants from tap water – but are they really necessary, and could they cause unintentional harm? If she can help it, Shima Chin-See