Remove BaseTmethod parameter and always use weekday/weekend base temperatures

[sunt05]

Summary

Removes the obsolete BaseTmethod parameter from the Fortran codebase and simplifies heating/cooling degree day (HDD/CDD) calculations to always use weekday/weekend-specific base temperatures.

Context

BaseTmethod was a legacy parameter that controlled whether to use:

• Method 1: Single BaseT_HC value for both heating and cooling
• Method 2: Separate weekday/weekend BaseT_Heating and BaseT_Cooling arrays

Since BaseT_HC was removed from input files in SUEWS v2023a, Method 1 became non-functional. The Fortran code had BaseTmethod hardcoded to 2 (always use Method 2), making it dead code.

Changes

Fortran Code

• suews_ctrl_const.f95: Removed BaseTMethod variable declaration
• suews_phys_dailystate.f95:
  • Removed BaseTMethod and BaseT_HC parameters
  • Removed these from update_DailyState_Day subroutine signature
  • Simplified HDD/CDD calculation by removing SELECT CASE logic
  • Now directly uses BaseT_Heating(iu) and BaseT_Cooling(iu) based on weekday/weekend

Code Simplification

! Before: SELECT CASE with two methods
SELECT CASE (BaseTMethod)
CASE (1)
   BaseT_Heating_use = BaseT_HC
   BaseT_Cooling_use = BaseT_HC
CASE (2)
   BaseT_Heating_use = BaseT_Heating(iu)
   BaseT_Cooling_use = BaseT_Cooling(iu)
END SELECT

! After: Direct assignment
BaseT_Heating_use = BaseT_Heating(iu)
BaseT_Cooling_use = BaseT_Cooling(iu)

Impact

User-Facing

✅ No breaking changes

• basetmethod was already removed from user-facing configuration in v2023
• Python/YAML API does not expose this parameter
• Pydantic data models have no reference to BaseTmethod
• Calculation behaviour unchanged (Method 2 was already hardcoded)

Internal

• Removes 21 lines of dead code
• Simplifies subroutine interfaces
• Aligns Fortran implementation with modern data model

Clarification: BaseT vs BaseTe

This change does NOT affect BaseT and BaseTe, which are separate vegetation parameters for:

• BaseT: Base temperature for growing degree days (GDD) in LAI phenology
• BaseTe: Base temperature for senescence degree days (SDD) in LAI phenology

These remain unchanged and are unrelated to anthropogenic heat flux calculations.

Testing

• Fortran code compiles successfully
• Existing tests pass
• No user-facing API changes

Fixes #144

[github-actions]

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