The main goal of this study is to determine how well large-scale temperature, salinity, upper ocean heat content (UOHC), and surface mixed layer fields and their variability can be reconstructed from the Argo observing system. The approach is to sample and reconstruct these oceanic fields from a coarse-resolution ocean general circulation model (OGCM), quantify the errors in the reconstructed fields, and analyze the factors controlling these errors. In particular, this study analyzes the effects of float movements on the spatial coverage and reconstruction of temporal variability. Overall performance of the simulated Argo array is good, and the reconstructed climatological means of such key quantities as the temperature, salinity, UOHC, and mixed layer depth are very close to the actual OGCM-simulated values in most of the global ocean. However, the differences between the reconstructed and actual fields (“reconstruction errors”) are more significant in several regions with strong currents, such as the Antarctic Circumpolar Current (ACC). The results also suggest that the detection of the year-to-year changes in UOHC in the ACC, in high-latitude North Atlantic, and near the coasts can be particularly problematic. As illustrated by sensitivity experiments, the main effect of float movements is to increase reconstruction errors. This adverse effect of float movements is the main cause of large errors in the UOHC interannual difference in the ACC. When the spatial sampling coverage is improved, for example, by increasing the number of floats, the accuracy of reconstruction improves substantially.