  Using detrended fluctuation analysis (DFA) we find that all continents are
persistent in temperature. The scaling exponents of the southern hemisphere
(SH) continents, i.e., South America (0.77) and Oceania (0.72) are somewhat
higher than scaling exponents of Europe (0.70), Asia (0.69) and North America
(0.64), but the scaling of Africa is by far the highest (0.86). The reason for
this is the location of Africa near the equator. The scaling exponents of the
precipitation are much smaller, i.e. between 0.55 (Europe) and 0.68 (North
America). The scaling exponent of Europe is near that of the random noise
(0.5), while the other continents are slightly persistent in precipitation. We
also show that the persistence disappears in all time series when shuffling the
data randomly, showing that persistence is not an intrinsic property of the
estimator. We find that the monthly temperature is the more persistent the more
wide area is analyzed. The persistence of precipitation is also increasing as a
function of area, although not so clearly. Furthermore, our analysis shows that
the persistence of the temperature decreases poleward in both hemispheres. The
persistence of precipitation is also highest at equatorial zones, and decreases
poleward, but is less dependent on the latitude than temperature. It seems that
the persistence of the precipitation is more dependent on the corresponding
climate type than the persistence of the temperature.
