In 1988, the Spanish Institute of Oceanography (CN-IEO/CSIC) initiated a series of oceanographic campaigns in the NAFO Regulatory Area, incorporating CTD measurements to characterize the water column. Temporal indices have been calculated using 5832 CTD profiles from May to the end of August, from 1988 to 2022.

Analysis of the bathymetry and thermohaline characteristics of the area reveal notable differences in salinity and temperature. Based on these findings, the Newfoundland banks can be divided into three zones: northeast, northwest, and south. These variations become more evident in surface salinity. In the northeast region (46-49°N, 43-47°W), salinity values are significantly higher than in the northwest (46-49°N, 47-49°W), while the southern area (42-46°N, 49-53°W) displays less pronounced extremes than the northern ones. These variations were proved by calculating Pearson correlation coefficients, which have low values showing a decoupling of the regions.

To generate the indices, two depths were considered: at 10 ± 5 m, to represent surface conditions, and at 250 ± 5 m, as average depth of the zone. 

For each parameter (temperature and salinity) the annual mean was calculated, resulting in twelve series which can be considered as reference for each zone and depth. These series have been detrended, producing anomaly indices that are suitable to use in climatic variability studies.