 Some recent studies reporting deep-ocean warming were referring to the upper half of the ocean, but below its topmost layer which goes down to about 700 metres' (0.43 mi) depth.According to the other NASA study, the upper layers of the Southern Ocean warmed at a much greater rate between 1970 and 2005 than previously thought (24–58 percent more than earlier estimates), because before the deployment of Argo buoys, temperature measurements in the Southern Ocean were "spotty, at best.