Six-month Pacific volume fits showed an eastern slope contrast but no clear east-west contrast in 1980-2024

We split later Pacific warm water volume change into western and eastern parts. We used fixed NOAA GODAS and ERSSTv5 records for 1980-2024. Identical fits controlled for both initial reservoirs, month and time. In 534 six-month starts, the warm-minus-cold temperature slope contrast was -0.844 for the eastern remainder and -0.312 for the west. Units are 10^14 cubic metres per degree C. The direct east-minus-west contrast was -0.532, with a conditional 95% three-year block interval of -1.378 to +0.215. Thus the primary test did not resolve a regional difference. The eastern contrast interval excluded zero, but this does not establish a larger eastern effect. Past-state and twelve-month checks gave negative regional-difference intervals; other checks did not. The result depends on model and window. One product pair, overlapping changes, few climate cycles and conditional uncertainty limit inference. No heat-transfer mechanism or forecast benefit is established. Code, aggregate evidence, paired block draws, source hashes, a numerical audit and a figure are included. Raw records remain outside the package.

ENSO · warm water volume · regional contrast · recharge · GODAS · uncertainty