Indian Ocean Dipole Monitoring Indices Climate Prediction Division Japan Meteorological Agency Regarding Indian Ocean Dipole (IOD) monitoring indices, the elnino/index/ directory contains two ASCII document files, Readme_iod.txt (this file) and one sub-directory for Sea Surface Temperature Indices (sstindex). 1. Sea Surface Temperature (SST) Indices SST indices consist of monthly mean SSTs, monthly mean SST anomalies (for the 1991 - 2020 base period), monthly mean SST deviations (for the latest sliding 30-year base period), and related three-month means for the IOD monitoring regions listed below since January 1950. The latest values are preliminary. Monthly mean SSTs are analyzed by JMA's Climate Prediction Division. The IOD Monitoring Regions - WIN and EIN - and Dipole Mode Index (DMI) are: WIN: 10N - 10 S 50 E - 70 E EIN: Eq. - 10 S 90 E - 110 E DMI: Difference between WIN and EIN The directory (elnino/index/sstindex) contains two sub-directories corresponding to the two base periods of 1991 - 2020 and the latest sliding 30-year period (directories: base_period_9120 and sliding_30year_period). SST indices are derived from MGDSST datasets (Kurihara et al. 2006) after June 2015 and those of COBE-SST2 (Hirahara et al. 2014) before this. 1-1. base_period_9120 directory This directory (elnino/index/sstindex/base_period_9120/) contains three sub-directories corresponding to the three IOD Monitoring indices. There are three data files under these sub-directories: (1) Monthly mean SST (file name: sst) (2) Monthly mean SST anomaly (file name: anomaly) (The base period for the normal is 1991 - 2020) (3) Three-month running mean SST anomaly (file name: 3rmean) (The base period for the normal is 1991 - 2020) Data files are in text format. The first line in each shows month, and subsequent lines contain data from 1949 to the latest year. The unit is degrees centigrade, and entries of 99.9 (or 99.90) represent undetermined values. 1-2. sliding_30year_period directory This directory (elnino/index/sstindex/sliding_30year_period/) contains three sub-directories corresponding to the DMI, WIN and EIN. There are three data files under each of these sub-directories: (1) Monthly mean SST climatological reference based on the latest sliding 30-year period (file name: sst) The SST climatological reference is defined as a linear extrapolation with respect to the latest sliding 30-year period. (2) Monthly mean SST deviation (file name: deviation) SST deviation is defined as the difference between the monthly mean SST and the climatological reference based on the latest sliding 30-year period. (3) Three-month running mean SST deviation (file name: 3rmean) Data files are in text format. The first line in each shows the month, and subsequent lines indicate data from 1949 to the latest year. The unit is degrees centigrade, and entries of 99.9 (or 99.90) represent undetermined values. Directory structure TOP | +-- elnino | +-- index | +-- Readme_iod.txt | +-- sstindex | +--- base_period_9120 | | | +-- WIN ---- sst, anomaly, 3rmean | | | +-- EIN ---- sst, anomaly, 3rmean | | | +-- DMI ---- sst, anomaly, 3rmean | +--- sliding_30year_period | +-- WIN ---- sst, deviaiton, 3rmean | +-- EIN ---- sst, deviaiton, 3rmean | +-- DMI ---- sst, deviaiton, 3rmean For inquiries relating to this data set, see http://www.data.jma.go.jp/tcc/tcc/contact.html. References Hirahara, S., M. Ishii, and Y. Fukuda, 2014: Centennial-scale sea surface temperature analysis and its uncertainty. J. Climate, 27, 57-75. Kurihara, Y., T. Sakurai, and T. Kuragano 2006: Global daily sea surface temperature analysis using data from satellite microwave radiometer, satellite infrared radiometer and in-situ observations. Weather Service Bulletin, 73, Special issue, s1-s18 (in Japanese).