Fix C4 dryness sensitivity typo in compute_chi#1805
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The C4 intercellular CO2 in `compute_chi` used the C3 dryness sensitivity `ξ_c3` instead of `ξ_c4`, biasing the blended χ (and the optimal-LAI water-limitation term that consumes it) at C4 and mixed C3/C4 grid cells. The per-timestep GPP path is unaffected; only `compute_chi` (used by the optimal-LAI model) had the error. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Patch release: bump version 1.10.2 -> 1.10.3 and freeze the NEWS.md `main` section as v1.10.3. Adds the two NEWS entries that were missing for changes merged since v1.10.2 (P-model ci NaN guard #1811, SIF kd_p2 + units #1812) alongside the already-logged C4 compute_chi fix #1805. Bumps the recorded ClimaLand version to 1.10.3 in the four tracked Manifests (.buildkite and docs, Julia 1.10 and 1.12); dependency versions are unchanged since #1811 refreshed them. No breaking changes, so the patch slot is bumped. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
compute_chicomputes the optimalci/caratio (χ) by blending a C3 and a C4 branch. The C4 intercellular CO₂ was computed with the C3 dryness sensitivityξ_c3instead ofξ_c4:Since
ξ_c4 = sqrt(β_c4 * (Kmm + Γstar) / (Drel * ηstar))uses a much smaller unit-cost ratio (β_c4≈β_c3 / 9), the C4 branch was getting the C3 χ, biasing the blended χ toward C3 behavior at C4 and mixed C3/C4 cells.Impact
compute_chiis consumed by the optimal-LAI model (optimal_lai.jl) for the water-limitation term, so the bias propagated into optimal LAI at C4/mixed cells.compute_blended_pmodel_photosynthesis) computesci_c3/ci_c4correctly with their own ξ and is not affected.fractional_c3 = 1) are unaffected since the C4 branch is weighted out.Change
One-line fix: use
ξ_c4for the C4 intercellular CO₂. Plus a NEWS entry.🤖 Generated with Claude Code