Reconstructed July-October evaporation shares showed no clear trend difference between Superior and Michigan-Huron in 1989-2022

We tested whether the July-October share of annual net evaporation rose faster in Superior than Michigan-Huron. We used monthly L2SWBM V3.0 medians and 34 July-June years ending in 1989-2022, within one model run. The share slopes were 1.62 and 1.41 percentage points per decade. Their paired difference was 0.20, with a conditional 95% five-year residual block interval of -1.19 to 1.56. Other block lengths and a shorter period left the difference uncertain. A planned September-November check gave a positive difference of 1.33 points per decade, so the seasonal definition matters. The primary result gives no clear difference and does not establish equal trends. The intervals exclude model posterior uncertainty. One reconstruction, changing input coverage, a short record, and a linear model limit inference. The package gives monthly evidence, source hashes, code, annual shares, bootstrap draws, a static figure, and independent numerical checks.

Great Lakes · evaporation · seasonal shares · L2SWBM · paired trends · null result · block bootstrap