Meridional Energy Transport – Uncertainty in Zonal Means

The meridional energy transport in the atmosphere and ocean is computed using atmospheric analyses from ECMWF and NMC, and net radiative flux from ERBE. An error analysis of the zonally-averaged total transport shows that errors of ±7 Wm⁻² in net flux produce transport errors of ±5PW at the equator, an error of ±9% in midlatitudes. Methods for correcting the mass non-conservation in transports derived from operational analyses are discussed. The ECMWF and NMC analysis systems now show remarkably similar zonally-averaged total energy transports, with normalized RMS differences of only 11%, despite 23% differences in Hadley-cell transports. The implied oceanic transport is derived along with an error estimate, and it is found to be broadly consistent with more direct measures of oceanic transport. The energy transport in NCAR’s CCM1 and CCM2 is computed and is found to be about 20% larger than observations.