Western volume control retained unequal Pacific temperature slopes for six-month basin volume change in 1980-2024

We tested whether initial western Pacific warm water volume accounts for a reported warm-minus-cold slope difference in later basin volume change. We used fixed NOAA GODAS and ERSSTv5 records for 1980-2024. The model used initial basin volume, month, time, surface temperature and its absolute value. Adding western volume left a slope difference of -1.155 in units of 10^14 cubic metres per degree C. The conditional 95% three-year block interval was -1.735 to -0.501. Its magnitude was 6.4% below the reference fit. The paired change was 0.079, with an interval of -0.006 to 0.273. History, seasonal, period, knot and large-event checks kept negative slope intervals. Thus initial western volume did not account for the fitted slope difference in these models. This is an association in revised products. It does not establish a physical cause, an actual heat flux or forecast skill. Few independent climate cycles, one data product pair and model assumptions limit the result. The package contains code, aggregate evidence, a numerical audit, a figure and exact source hashes. External raw data and monthly records stay outside the package.

ENSO · warm water volume · GODAS · conditional association · ocean recharge · asymmetry