Inferring ocean heat content variations from satellite altimetry and model data

Considering ocean bottom pressure change, we estimate the heat content variations of the global ocean and the China Sea by using merged altimetric data from 2003 to 2008. The improved method includes the effect of ocean bottom pressure (OBP) variations and the effect of thermal expansion coefficient variations with ocean water's depth. The estimation accuracy of ocean heat content variation is improved in mid and high latitude areas. In North Pacific Region I (30 degrees N similar to 50 degrees N, 170 degrees E similar to 190 degrees E), South Indian Region II (40 degrees S similar to 60 degrees S, 100 degrees E similar to 120 degrees E) and South Pacific Region III (40 degrees S similar to 60 degrees S, 100 degrees W similar to 120 degrees W) where OBP changes significantly, the root mean squares of the improved method reduce by 16.3%, 60.5%, and 48.4%. The study also indicates that the accuracy of satellite altimetry and the effect of salinity are the main factors which affect heat content estimation accuracy in mid and high latitude areas. Ocean heat content mainly changes annually in the East China Sea and the Yellow Sea. Besides the annual variation, semiannual and interannual variations exist in the South China Sea. There exists an increasing tendency of heat content in the South China Sea.