Notes

• OISST v2.1 (NOAA/NCEI 0.25° daily) via NOAA PSL; anomalies vs the 1991–2020 daily climatology. Region boxes are listed under each time series.
• Relative Niño 3.4 = Niño 3.4 anomaly minus the 20°S–20°N global-tropics anomaly; MDR minus Tropics likewise for the Atlantic Main Development Region (10–20°N, 20–85°W).
• ARMOR3D (Copernicus Marine multi-observation 3D temperature analysis from Argo profiles, satellite SST and sea level; daily, 1/8°, 50 levels) for the subsurface section and weekly Hovmöllers; climatology 1993–2020; near-real-time stream lags about a week.
• GODAS (NCEP Global Ocean Data Assimilation System, bias-corrected monthly) kept as a secondary model-based view; updates mid-month for the previous month.
• ELI (Williams & Patricola 2018): mean longitude of 5°S–5°N Pacific cells whose SST exceeds the tropics-wide (20°S–20°N) mean. The daily version runs on OISST at 1° with a 15-day trailing mean and updates with the SST page; the monthly version uses ERA5. Values east of 180° indicate El Niño-like convection.