Seasons by week_of_year: Winter 1–9 and 49–52; Spring 10–22; Summer 23–35; Autumn 36–48. Note: source week_status is derived from n_obs; valid_week is treated as valid_data. plot_status top tier requires valid_data on both sides and n_obs ≥ 6 each. Years ≥ 2000. Scatter cap 50,000 points per view.