Summary of the Article:

Stress-Deciduous Offset Triggers

The stress-deciduous phenology algorithm is initiated by any one of three conditions: a sustained period of dry soil, a sustained period of cold temperature, or a daylength shorter than 6 hours. The offset period can only be triggered after the most recent onset period is complete.

Dry Soil Condition:
The offset soil water index accumulator (OSWI_sum) increases when the soil water potential (Ψs,3) is less than or equal to the offset soil water potential threshold (Ψoffset = -0.8 MPa). It decreases when Ψs,3 is greater than the onset soil water potential threshold (Ψonset). An offset period is triggered if OSWI_sum is greater than or equal to the critical value (OSWI_sum_crit = 15).

Cold Temperature Trigger:
The offset freezing day accumulator (OFD_sum) increases when the soil temperature (Ts,3) is less than or equal to the freezing point (TKFRZ). It decreases when Ts,3 is greater than TKFRZ. An offset period is triggered if OFD_sum is greater than the critical value (OFD_sum_crit = 15).

Offset Period:
The offset counter (t_offset) is set to 86,400 × n_days_off, where n_days_off is a constant value of 15 days. The offset counter is decremented on each time step until it reaches zero, signaling the end of the offset period.