Summary:

Seasonal-Deciduous Offset Trigger

After the completion of an onset period, and once past the summer solstice, the offset (litterfall) period is triggered when daylength is shorter than 39300 s. The offset counter is set at the initiation of the offset period, where n_days_off is set to a constant value of 15 days. The offset counter is then decremented on each time step after the initiation of the offset period, until it reaches zero, signaling the end of the offset period.

The key points are:

1. The offset period is triggered by daylength being shorter than 39300 s after the summer solstice.
2. The offset counter is initialized to 86400 * n_days_off, where n_days_off is 15 days.
3. The offset counter decrements on each time step until it reaches zero, marking the end of the offset period.