Long-Range Correlations of Global Sea Surface Temperature

Scaling behaviors of the global monthly sea surface temperature (SST) derived from 1870-2009 average monthly data sets of Hadley Centre Sea Ice and SST (HadISST) are investigated employing detrended fluctuation analysis (DFA). The global SST fluctuations are found to be strong positively long- range correlated at all pertinent time- intervals. The value of scaling exponent is larger in the tropics than those in the intermediate latitudes of the northern and southern hemispheres. DFA leads to the scaling exponent alpha = 0.87 over the globe (60 degrees S similar to 60 degrees N), northern hemisphere (0 degrees N similar to 60 degrees N), and southern hemisphere (0 degrees S similar to 60 degrees S), alpha = 0.84 over the intermediate latitude of southern hemisphere (30 degrees S similar to 60 degrees S), alpha = 0.81 over the intermediate latitude of northern hemisphere (30 degrees N similar to 60 degrees N) and alpha = 0.90 over the tropics 30 degrees-S similar to 30 degrees N [fluctuation F(s) similar to s(alpha)], which the fluctuations of monthly SST anomaly display longterm correlated behaviors. Furthermore, the larger the standard deviation is, the smaller long- range correlations (LRCs) of SST in the corresponding regions, especially in three distinct upwelling areas. After the standard deviation is taken into account, an index chi = alpha* sigma is introduced to obtain the spatial distributions of chi. There exists an obvious change of global SST in central east and northern Pacific and the northwest Atlantic. This may be as a clue on predictability of climate and ocean variabilities.