This paper is presented in the context of sensitivity analysis (SA) of large-scale data assimilation (DA) models. We studied consistency. convergence. stability and roundoff error propagation of the reduced-space optimization technique arising in parallel 4D Variational DA problems. https://www.bekindtopets.com/save-now-Aqua-Pure-3MFF101-Full-Flow-Drinking-Water-System-Replacement-Cartridge-flash-choice/