Persistence of temperature and precipitation: From local to global anomalies

Abstract

ract: Using detrended fluctuation analysis (DFA) we find that the all continents are persistent in temperature. The scaling exponents of the southern hemisphere (SH) continents, i.e., South America (α=0.78) and Oceania (0.75) are somewhat higher than scaling exponents of Europe (0.70), Asia (0.69) and North America (0.65), but the scaling  of Africa is by far the highest (0.89). The scaling exponents of the precipitation are much smaller, i.e., between 0.54 (Europe) and 0.67 (North America). The scaling exponent of Europe is near the exponent of random Brownian noise, which is 0.5. The other continents are slightly persistent in precipitation. The slopes of the logarithmic power spectra of the continents are in line with the scaling exponents confirming the DFA analysis results. We also show that the persistence is real and not the intrinsic property of the data itself. We find that scaling exponent α, i.e., persistence of the monthly temperature increases when going from local to larger area averages, at least in the case where climate type does not change much. The situation is not so obvious for the monthly precipitation. We also show that the three southernmost climate regions of USA, Ohio Valley, South and Southeast, have smaller scaling exponents for temperature anomalies, and are thus less persistent in temperature than other six climate regions. On the other hand they are slightly more persistent in precipitation that the other regions. The scaling exponents of the monthly temperature anomalies of the latitude zones of land area are 0.71 and 0.68 for the southern zones S44-S24, and S64-S44, respectively. For the northern zones N24-N44, N44-N64 and N64-N90, the scaling exponents are between 0.67-0.70.  Interestingly the scaling exponents are extremely high for the equatorial zones S24-EQ and EQ-N24, i. e., 1.02 and 0.95, respectively. The corresponding exponents of the monthly precipitation anomalies are between 0.55-0.61 for other zones than S24-EQ and EQ-N24, which have exponents 0.72 and 0.77, respectively.