Power-law persistence in the atmosphere and in the oceans

The persistence of the weather is a well-known phenomenon. If, for example, one day is sunny and warm, there is a high tendency that the next day remains similar. In this paper, we review recent results showing that the long-term persistence, characterized by the correlation C(s) of temperature variations separated by s days, decays for large s as a power law. For continental stations, the exponent is always close to 0.7, while for stations on islands as well as for sea surface temperatures, the exponent is close to 0.4. In contrast to the temperature fluctuations, the fluctuations of the rainfall usually are not characterized by long-term power-law correlations but rather by short-term correlations. The universal persistence law for the temperature fluctuations on continental stations represents an ideal (and uncomfortable) test bed for the state-of-the-art global climate models and allows to evaluate their performance.