Data sources for indices:
ERSST.V5 : Huang, B., Peter W. Thorne, et. al, 2017: Extended Reconstructed Sea Surface Temperature version 5 (ERSSTv5), Upgrades, validations, and intercomparisons. J. Climate
Climatology : 1991-2020

WTIO  : SSTA averaged in [50ºE-70ºE, 10ºS-10ºN]
SETIO : SSTA averaged in [90ºE-110ºE, 10ºS-0]
DMI  = WTIO - SETIO

  Year   Month     WTIO      SETIO       DMI
  2021     7       0.07       0.55      -0.48
  2021     8       0.07       0.41      -0.34
  2021     9       0.15       0.27      -0.13
  2021    10      -0.02       0.66      -0.69
  2021    11      -0.01       0.37      -0.38
  2021    12       0.12       0.32      -0.20
  2022     1       0.28       0.55      -0.26
  2022     2      -0.10       0.27      -0.37
  2022     3      -0.06       0.06      -0.11
  2022     4      -0.03       0.34      -0.37