资源环境科技发展态势分析平台

Monthly-to-decadal variability of the regional precipitation over Intertropical Convergence Zone and north-Atlantic and north-Pacific storm tracks was investigated using ERA-20C reanalysis. Satellite-based precipitation (P) and evaporation (E) climatological patterns were well reproduced by ERA-20C. Regional P and E monthly time series displayed similar to 20% differences, but these decreased rapidly with time scale (similar to 10% at yearly time scales). Spectral analysis showed good scale-by-scale statistical agreement between ERA-20C and observations. Using ERA-Interim showed no improvement despite the much wider range of information assimilated (including satellites). Remarkably high Detrended Cross-Correlation Analysis coefficients (rho(DCCA) > 0.7 and often rho(DCCA) > 0.9) revealed tight links between the nonperiodic variability of P, moisture divergence (DIV), and pressure velocity (omega) at monthly-to-decadal time scales over all the wet regions. In contrast,.DCCA was essentially nonsignificant between nonperiodic P and E or sea surface temperature (SST). Thus, the nonperiodic monthly-to-decadal variability of precipitation in these regions is almost fully controlled by dynamics and not by local E or SST (suggested by Clausius-Clapeyron relation). Analysis of regional nonperiodic standard deviations and power spectra (and respective spectral exponents, beta) provided further robustness to this conclusion. Finally, clear transitions in beta for P, DIV, and. between tropical and storm track regions were found. The latter is dominated by transient storms, with energy accumulation at synoptic scales and beta < 0.1 at monthly-to-decadal time scales, implying that variability and information creation decrease rapidly with time scale. Larger beta values (0.2 to 0.4) were found in the tropics, implying longer-range autocorrelations and slower decreasing variability and information creation with time scale, consistent with the important forcing from internal modes of variability (e.g., El Nino-Southern Oscillation).