Icepack version 1.5.3 is being released with CICE6.6.3. This is a minor release update from the Icepack1.5.2 release from August, 2025. This release is being done primarily to update the CMIP output variables in CICE. But this release also improves residual ice handling and adds options for coupling with externally generated wave height. The ICEPACK interfaces have had some minor changes that may not be backward compatible. Major Changes #543 Update residual ice zapping, add namelist to control thresholds. THIS CHANGES ANSWERS Bug fixes #552 Enforce minimum snow grain radius THIS CHANGES ANSWERS for configurations using prognostic snow grain radius #542 Update Tsnice computation, changes history output for f_sitempsnic. Enhancements #545 Add option for externally generated significant wave height. Some of the Icepack interfaces have been updated, this is not backwards compatible for calls to subroutine icepack_step_wavefracture and may not be backwards compatible for calls to icepack_step_therm2 #541 Update automated check for job completion for test suites #539 Removed some unused code, updated information about conda installation on Mac. Documentation #549 Update and clarify uv and par radiation descriptions in code comments and documentation #547 Fix typo in documentation Summary of Icepack interface changes icepack_parameters Add wave_height_type (optional) Add itd_area_min, itd_mass_min (optional) icepack_step_therm2 Remove dwavefreq (was optional) icepack_step_wavefrac Remove wave_spec_type (redundant, set in icepack_parameters) Add wave_height (optional)