Replication package for "Implicit-tuning signal quantified through a tri-experiment design in a legacy spectral GCM"

This archive contains the derived statistical products, analysis scripts, and figures supporting the manuscript "Implicit-tuning signal quantified through a tri-experiment design in a legacy spectral GCM" (D. Vokhmintsev, submitted to the Journal of Advances in Modeling Earth Systems, 2026). The underlying experiment is a three-member initial-condition ensemble of 30-year AMIP-style integrations (1979-2008) of the MGO atmospheric general circulation model in its T42L25 spectral configuration, contrasting three implementations of the vertical-exchange routine ve_r2: REF (legacy code with inter-latitude state leakage), CTRL_A (zero-reinitialization of the working arrays at every call), CTRL_B (per-latitude snapshot and restore through a dedicated memory module). The included data products are pooled-paired ensemble t-test fields with Trenberth (1984) effective-degrees-of-freedom correction and Benjamini -- Hochberg FDR control at q = 0.05, model-vs-observation validation Taylor statistics against ERA5, CERES EBAF, GPCP and ISCCP-H, inter-member consistency F-ratio fields, and annual global-mean diagnostics. Four manuscript figures and the runnable scripts that reproduce all manuscript tables and figures from these derived products are included. The MGO atmospheric GCM source code is intellectual property of the Voeikov Main Geophysical Observatory (Saint Petersburg, Russia) and is not redistributed in this package. Per-member monthly model output and per-configuration climatologies are held privately by the author. The diff/patch of the GCM modules implementing the structural fix VE_JRESET and the deterministic-reduction modules referenced in the manuscript's bitwise-reproducibility theorem is deposited as the companion archive (10.5281/zenodo.19653300); Supplementary Information Section S3 of the manuscript maps each theorem condition to specific files and line ranges in that archive. Software environment, reproduction instructions, and the full list of contents are documented in <code>README.md</code>. Build provenance (source commits, compiler version, flags, MD5 checksums) is in PROVENANCE.md. SHA-256 hashes of all 178 files are in MANIFEST.sha256. Scripts are released under the MIT licence (LICENSE.code); derived data and figures under CC-BY-4.0 (LICENSE.data).