GRAD and CTA ENSO Indices

This dataset includes CSV and NetCDF4 files of the domain averaged zonal SST gradient (GRAD) and the Cold Tongue Area (CTA) indices in the equatorial Pacific. These are 3-month rolling averages starting at DJF 1959/1960 and ending at MAM 2025. These indices are developed and described in Gifford et al. 2026 [submitted]. The indices were calculated using ERSSTv5 data. The GRAD is derived from the monthly domain average zonal SST gradient in the domain ±5N and 150 to 250E. The CTA is the area within the 28.5°C contour in the same domain as the GRAD. The GRAD carries units of °C/km and the CTA has the units km2.