COSP/RTTOV inputs copied over 1:pver instead of reduced domain ktop:pver in cospsimulator_intr.F90 #1591

Summary

Several COSP/RTTOV input fields in cospsimulator_intr.F90 are copied over the full column 1:pver instead of the reduced COSP domain ktop:pver used by their neighbors, producing vertically shifted profiles (or out-of-bounds access) in high-top configurations.

Location

src/physics/cam/cospsimulator_intr.F90:2327-2378

cospstateIN%at  = state%t(:ncol,ktop:pver)   ! correct pattern
cospstateIN%tca = cld(1:ncol,1:pver)         ! wrong: full column
cospstateIN%co2 = co2(1:ncol,1:pver)         ! wrong
...
cospstateIN%DeffIce(1:ncol,1:pver) = dei(1:ncol,1:pver)  ! out-of-bounds write

Problem

COSP runs on nlay = pver - ktop + 1 levels and most fields are correctly subset ktop:pver. But the fields added in the RTTOV / COSP-2.2.1 integration (tca, co2, ch4, n2o, cloudIce, cloudLiq, DeffLiq, DeffIce) use 1:pver. When ktop > 1 (any high-top configuration, e.g. WACCM):

• Whole-array assignments silently reallocate the derived-type components to the wrong size, so profiles are vertically shifted by ktop−1 layers relative to the correctly-subset T/q/p.
• The Deff* lines are non-conforming / out-of-bounds reads and writes.

Impact

All RTTOV radiances and tca-dependent COSP diagnostics are misaligned (or memory is corrupted) in high-top runs. No effect in default low-top CAM where ktop = 1. Diagnostics only.

Suggested fix

Subset all of these fields ktop:pver to match their neighbors.

Found via a systematic line-by-line scientific code review of src/physics/cam/ at commit 21a78294 (≈cam6_4_180). This is a candidate bug identified by code inspection; it has not yet been confirmed by a model run. An issue-tracker search on 2026-06-11 found no existing report.