These are Hovmöller diagrams (Longitude x Time) showing either weekly average sea surface temperature anomalies (SSTA) or monthly potential temperature anomalies at depths of 55 and 155 meters, averaged over 5°S to 5°N, for the past year across the equatorial Pacific Ocean. These diagrams can be used to track the evolution and migration of sub-surface temperature anomalies that could contribute to changes in sea surface temperatures in the future in the key NINO regions across the equatorial Pacific used to monitor the development of ENSO.
The sea surface temperature anomalies are contoured at an interval of 0.5°C, and the contours and shading start at +/- 0.5°C. Negative anomalies (in shades of blue) indicate where the weekly average temperature was below the 1991-2020 mean for that week of the year, and positive anomalies (in shades of yellow and red) indicate where temperatures were above the long-term mean. The longitude domain extends from 120°E to 80°W, and data from the past year are shown, with time increasing vertically.
For the sub-surface potential temperature anomalies, contours are drawn at intervals of 0.5°C; negative values (in shades of blue) indicate below-normal potential temperatures with respect to the 1991-2020 mean, and positive values (in shades of yellow and red) represent above-normal potential temperatures with respect to the 1991-2020 mean. The longitude domain extends from 120°E to 80°W, and data from the last year are shown, with time increasing vertically.
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