In terms of buoyancy flux, winter mixed layer depth, and mode water thickness in summer, we explore the causes why reemergence does not occur in the formation areas of the North Pacific eastern subtropical mode water (NPESTMW) and the North Atlantic Madeira mode water (NAMMW). It is found that as season goes by, the thicknesses of these mode waters become quickly thinner due to vigorous salt-finger type convection throughout the water column in contrast to those of the other mode waters. Correspondingly, mode waters lying under the shallow summer mixed layer quickly lose their water properties. In addition, it is found that in these areas, net buoyancy flux integrated through a year is almost zero, while in the other mode water areas where reemergence occurs, net buoyancy flux is negative (the ocean's loss) to some degree. Based on these facts, we can conclude that the formation areas of NPESTMW and NAMMW are the regions having unfavorable conditions for an occurrence of reemergence.