MEI timeseries from Dec/Jan 1940/50 up to the presentMEI Index (last update: 8 January 2008) Bimonthly MEI values (in 1/1000 of standard deviations), starting with Dec1949/Jan1950, thru last month. More information on the MEI can be found on the MEI homepage. Missing values are left blank. Note that values can still change with each monthly update, even though such changes are typically smaller than +/-0.1. All values are normalized for each bimonthly season so that the 44 values from 1950 to 1993 have an average of zero and a standard deviation of "1". Responses to 'FAQ' can be found below this table: YEAR DECJAN JANFEB FEBMAR MARAPR APRMAY MAYJUN JUNJUL JULAUG AUGSEP SEPOCT OCTNOV NOVDEC 1950 -1.073 -1.151 -1.266 -1.045 -1.411 -1.372 -1.311 -1.06 -.6 -.408 -1.149 -1.24 1951 -1.054 -1.201 -1.242 -.513 -.26 .389 .75 .871 .839 .743 .722 .473 1952 .421 .144 .113 .243 -.303 -.663 -.196 -.148 .371 .32 -.331 -.096 1953 .05 .405 .245 .696 .826 .239 .433 .257 .556 .11 .075 .315 1954 -.012 -.047 .075 -.656 -1.489 -1.547 -1.412 -1.436 -1.189 -1.366 -1.099 -1.116 1955 -.751 -.675 -1.219 -1.667 -1.647 -2.245 -1.885 -1.995 -1.777 -1.766 -1.858 -1.862 1956 -1.435 -1.309 -1.383 -1.16 -1.356 -1.505 -1.195 -1.117 -1.352 -1.471 -1.078 -1.03 1957 -.986 -.436 .087 .387 .884 .76 .959 1.11 1.163 1.096 1.116 1.19 1958 1.472 1.455 1.3 .886 .743 .881 .674 .378 .068 .083 .422 .692 1959 .518 .785 .473 .151 .015 -.01 -.21 .061 -.027 -.108 -.181 -.264 1960 -.285 -.248 -.083 -.032 -.345 -.261 -.316 -.253 -.512 -.386 -.338 -.436 1961 -.216 -.236 -.016 .043 -.287 -.129 -.252 -.328 -.351 -.578 -.397 -.644 1962 -1.08 -1 -.785 -1.044 -.914 -.819 -.789 -.54 -.508 -.674 -.665 -.52 1963 -.771 -.906 -.684 -.784 -.437 -.074 .382 .655 .752 .868 .944 .713 1964 .866 .503 -.325 -.662 -1.277 -1.127 -1.379 -1.536 -1.295 -1.194 -1.26 -.935 1965 -.562 -.336 -.238 .103 .524 .942 1.436 1.516 1.452 1.231 1.375 1.265 1966 1.333 1.187 .643 .441 -.154 -.177 -.115 .164 -.121 -.058 .019 -.171 1967 -.454 -.889 -1.059 -1.05 -.413 -.313 -.62 -.5 -.705 -.728 -.426 -.396 1968 -.664 -.831 -.693 -1.004 -1.085 -.758 -.494 -.145 .192 .432 .585 .364 1969 .649 .803 .392 .594 .719 .799 .434 .277 .213 .501 .671 .369 1970 .359 .375 .17 -.044 -.154 -.679 -1.096 -1.009 -1.241 -1.094 -1.079 -1.221 1971 -1.181 -1.495 -1.77 -1.815 -1.444 -1.466 -1.236 -1.265 -1.467 -1.439 -1.384 -1.028 1972 -.55 -.376 -.22 -.143 .534 1.13 1.815 1.763 1.555 1.627 1.722 1.771 1973 1.784 1.552 .881 .526 -.125 -.767 -1.072 -1.354 -1.697 -1.66 -1.471 -1.828 1974 -1.91 -1.784 -1.685 -1.58 -.999 -.652 -.801 -.698 -.615 -1.007 -1.223 -.893 1975 -.488 -.546 -.859 -.926 -.863 -1.181 -1.503 -1.687 -1.812 -1.927 -1.75 -1.781 1976 -1.597 -1.358 -1.248 -1.173 -.48 .277 .617 .715 1.028 .911 .429 .545 1977 .484 .287 .186 .558 .369 .488 .847 .69 .774 .992 1.001 .89 1978 .762 .888 .952 .174 -.358 -.533 -.379 -.207 -.357 .002 .231 .406 1979 .622 .395 .036 .318 .423 .47 .376 .628 .797 .702 .752 1.032 1980 .629 .523 .677 .873 .907 .882 .788 .368 .268 .201 .247 .099 1981 -.32 -.213 .422 .641 .078 -.027 -.037 -.14 .129 .125 -.007 -.151 1982 -.285 -.189 .065 -.083 .443 .994 1.604 1.764 1.799 2.031 2.456 2.448 1983 2.723 2.965 3.148 3.007 2.567 2.231 1.77 1.211 .515 .063 -.139 -.187 1984 -.357 -.515 .202 .443 .12 -.136 -.198 -.241 -.101 .026 -.305 -.58 1985 -.56 -.595 -.719 -.471 -.741 -.138 -.197 -.426 -.559 -.134 -.052 -.28 1986 -.308 -.235 .04 -.103 .319 .311 .39 .722 1.092 1.02 .859 1.188 1987 1.262 1.193 1.687 1.875 2.128 1.924 1.833 2.011 1.897 1.654 1.233 1.28 1988 1.152 .702 .5 .335 .091 -.653 -1.195 -1.315 -1.534 -1.359 -1.484 -1.338 1989 -1.075 -1.205 -.978 -.71 -.491 -.315 -.479 -.55 -.269 -.336 -.069 .152 1990 .232 .558 .871 .412 .566 .436 .098 .107 .42 .316 .373 .343 1991 .313 .29 .352 .334 .689 1.041 1.019 1.039 .726 1.006 1.172 1.254 1992 1.711 1.848 2.004 2.248 2.106 1.798 1.018 .591 .472 .586 .513 .619 1993 .632 .918 .953 1.377 1.982 1.558 1.125 1.052 1.009 1.046 .83 .592 1994 .406 .2 .137 .445 .62 .622 .828 .615 .636 1.331 1.241 1.195 1995 1.18 .87 .784 .32 .447 .478 .283 .051 -.346 -.427 -.48 -.499 1996 -.603 -.62 -.264 -.485 -.232 -.012 -.175 -.261 -.328 -.374 -.103 -.35 1997 -.427 -.482 -.174 .468 1.1 2.316 2.648 2.876 2.847 2.217 2.33 2.217 1998 2.417 2.699 2.721 2.614 1.987 1.144 .345 -.194 -.567 -.79 -1.085 -.945 1999 -.982 -1.024 -.896 -.877 -.644 -.384 -.526 -.729 -.873 -.924 -1.043 -1.208 2000 -1.093 -1.133 -.926 -.338 .034 -.258 -.218 -.168 -.238 -.326 -.733 -.624 2001 -.497 -.627 -.55 -.079 .164 0 .147 .288 -.229 -.328 -.248 -.043 2002 .001 -.138 -.079 .415 .883 .843 .557 .856 .776 .905 .982 1.148 2003 1.235 .91 .813 .387 .039 -.004 .039 .263 .452 .557 .54 .349 2004 .319 .374 -.082 .271 .442 .268 .457 .61 .561 .53 .816 .682 2005 .3 .742 .93 .556 .712 .464 .423 .426 .201 -.251 -.387 -.525 2006 -.362 -.402 -.553 -.593 -.011 .47 .639 .741 .859 1.012 1.277 .966 2007 1.037 .537 .133 .088 .179 -.307 -.291 -.434 -1.109 -1.117 -1.121 -1.121 (1) If you are trying to relate the MEI to monthly values of, say, precipitation, it may be expedient to use the MEI value of month(i-1) and month(i) as if it were the value for month(i) only. Since it takes a week or so for the global atmosphere to respond to tropical SST anomalies, the resulting lag is thus built into the analysis (I have verified this for southwest U.S. precipitation). (2) Next update: 8 February 2008 (or earlier) (3) Are there MEI values available prior to 1950? YES (I have some), and NO (I do not deem them fit for distribution yet). Since I am currently working on other projects, I cannot foresee when I will get to finalizing such historic MEI analyses. Based on preliminary data quality analyses, such values would be most reliable around 1900. Aside from the World Wars, the biggest problem is the decreased importance of ENSO during the 1920-50 period, as well as big changes in observing techniques around 1941 in particular. Let me know if you are interested in such historical MEI values, and I will keep you in mind for future updates on this. (4) Why do I believe that the MEI is better for monitoring ENSO than the SOI or various SST indices? In brief, the MEI integrates more information than other indices, it reflects the nature of the coupled ocean-atmosphere system better than either component, and it is less vulnerable to occasional data glitches in the monthly update cycles. Now, if you are interested in ENSO impacts in a very specific part of the world, I would suggest that you obtain other ENSO indices as well and establish which one best fits your needs. For instance, in Australia, Darwin sea level pressure and/or the SOI may be more appropriate than the MEI. My claim here is that the MEI does a better job than other indices for the overall monitoring of the ENSO phenomenon, including, for instance, world-wide correlations with surface temperatures and rainfall. (5) I have been asked about MEI-like indices for the Indian Ocean, and at present I have no such project under way, nor do I know of any such data. (6) Given the integrative approach of the MEI, I am very hesitant to give out subsets of the data that make up the MEI (for instance, its SST or SLP components alone). Therefore, I will not honor requests of that nature. (7) If you are interested in MEI predictions, please contact me directly under my e-mail address: Klaus Wolter (kew@cdc.noaa.gov). Link to ranked MEI values is here. Go back to MEI homepage.