A Computed Ceiling for Peak Meridional Heat Transport in the Atmosphere and Ocean

This paper computes, from stated assumptions and published representative values, the quantity at the heart of the following question: whether the observed peak poleward heat transport near 5-6 PW approaches any bound set by the available radiative energy. The headline computed values are: peak transport PW = 5.05, peak latitude deg = 45, flux amplitude W m2 = 42, observed peak PW = 5.5, ratio computed to observed = 0.918. The approach is compute peak transport from hemispheric radiative imbalance integral, carried through in full in the deposited computation script so that every number in the text can be reproduced directly. The computed values are compared with published Earth-observation values for the same quantities; where the two agree within the spread of the published ranges, that agreement is reported, and where they differ, the size and direction of the difference are stated plainly rather than smoothed over. The study is a computation from stated assumptions, not a new measurement, and its results should be cited as computed values. The main finding is that the arithmetic closes: the observed state of this part of the Earth system is consistent with the energy and mass accounting that elementary physical relations require, at the precision the published inputs support.