The heat distributions in the upper layers of the ocean have been studied and some important low frequency oscillations (LFOs) are already found and quantified by using various characteristic factors. In this paper, the 'heat center' of a sea area is defined with a simple method. Then the temperature data set of the upper layer of the global ocean (from surface down to 400 m, 1955 - 2003) is analyzed to detect the possible LFOs. Not only some zonal LFOs, which were reported early, but also some strong LFOs of the vertical and meridional heat distribution, which might imply some physical sense, are detected. It should be noted that the similar vertical oscillation pattern can be found in the Pacific Ocean, Atlantic Ocean and Indian Ocean. Results from some preliminary studies show that the vertical LFO might be caused by the solar irradiance anomalies. This study may help reveal some unknown dynamical processes in the global oceans and may also benefit other related studies.