El Niño Southern Oscillation (ENSO)

ENSO Index Dashboard

ENSO is an phenomena which extends over large spatial area and can have a different seasonal evolution from event to event. The different patterns have implications for climate impacts both locally and at a distance. The following indices all help characterize ENSO but at different locations and time scales. See the PSD news story on flavors of ENSO. Also see the webpage to analyze and compare time series. There are two products available. First are plots of the progression of the current event is compared to historic El Niño events. There is a shorter time-series (1948 onwards) index section and a longer (1870 onwards) one. There are less time series that cover from 1870 to present. Second are time-series plots of various ENSO indices. Events are selected using the MEI.ext and the ERSST V4 SST datasets as a guide. See event year lists.

There is also a La Niña dashboard looking at the current index values and comparing them to historic La Nina events.


These plots show current 2015 event values of various indices vs. seven events since 1948.
Name Description Current value vs Historic El Niño Events Latest Value Date

MEI

A multi-variate index of ENSO which uses SST and winds. It is calculated using the ICOADS dataset. Produced at NOAA/ESRL PSD. -0.45 Sep 2017

Niño 4

SST anomalies averaged over the NINO4 region 5°North-5°South; 160°East-150°West (western most of Niño indices). Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/CPC). 0.07 Sep 2017

Niño 3.4

SST anomalies averaged over the NINO34 region 5°North-5°South;170-120°West. Total SSTs also available for this region. Correlates well with teleconnections to North America. Calculated from the Monthly NOAA ERSST V4 (at NOAA/CPC). -0.43 Sep 2017

Niño 3

SST anomalies averaged over the NINO3 region 5°North-5°South;150°West-90°West. Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/CPC). -0.74 Sep 2017

Niño 1.2

SST anomalies averaged over the NINO1 and NINO2 regions 0-10°South;90°West-80°West (eastern most of the Niña indices). Total SSTs also available for this region. Calculated from the Monthly ERSST V4 (at NOAA/CPC). -0.81 Sep 2017

ONI

Oceanic Niño Index: 3 month running mean of ERSST.v4 SST anomalies in the Niño 3.4 region (5°N-5°S, 120°-170°W) Calculated from the ERSST V4 (at NOAA/CPC). -0.15 Aug 2017

BEST

Bivariate El Nino- Southern Oscillation Index: The Niño 3.4 SST and SOI are normalized and combined. SST is from the HadISST1.1. SOI is from NOAA/CPC. Produced at NOAA/ESRL PSD. -0.40 Jun 2016

SOI

Southern Oscillation Index: Difference between standardized Darwin and standardized Tahiti surface pressure values. It represents the atmospheric component of the ENSO. The sign is opposite that of the Nino indices and it is noisier than those indices. From NOAA/CPC 1.00 Sep 2017

TNI

Trans-Niño Index: Standardized Niño 1+2 minus the Niño 4 with a 5 month running mean applied (restandardized). It represents the gradient of the SST in the ENSO region of the tropical Pacific. Calculated from the Monthly HadISST1.1 dataset. -1.12 Jun 2017

PDO

Pacific Decadal Oscillation: leading principal component of monthly SST anomalies in the North Pacific Ocean, poleward of 20N (global SST mean removed). Calculated from the NOAA OISST V1 and V2 (U of Washington). 0.32 Sep 2017

PNA

Pacific NorthAmerican Pattern. The PNA is one of the most prominent modes of extratropical variability in the northern Hemisphere. This version is calculated at NOAA/CPC. It is based on EOF's calculated from monthly anomalies of 500mb height from the NCEP Reanalysis. -0.32 Sep 2017

OLR

Outgoing Longwave Radiation (OLR) area averages over the central equatorial Pacific (160°E-160°W). OLR is a good measure of convection. Negative OLR represents increased convention. Calculated at NOAA/CPC. 0.80 Sep 2017

Heat Content

Tropical Pacific integrated temperature anomalies (0-300m) 160°E–80°W. Calculated at NOAA/CPC from the GODAS dataset. -0.57 Sep 2017

200mb Zonal Winds

200mb Zonal Wind anomalies 2.5S-2.5N; 165W-110W. Calculated at NOAA/PSD from the NCEP R1. -1.16 Sep 2017

ESPI Precip Index

ENSO Precipitation Index. The index is based on rainfall anomalies in two rectangular areas, one in the eastern tropical Pacific (10°S-10°N, 160°E-100°W) and the other over the Maritime Continent (10°S-10°N, 90°E-150°E). The first step of the procedure involves moving a 10° by 50° block around each box; the minimum and maximum values of all possible blocks is obtained for each box and these are combined to estimate an El Niño precipitation index (EI) and a La Niña precipitation index (LI). The EI and LI are in turn combined to create the ESPI index. Finally, the ESPI index is normalized to have zero mean and unit standard deviation. Calculated at UMD. -0.47 Nov 2016
These plots show current 2015 event values of various indices vs 9 events since 1870.
Name Description Current value vs Historic El Niiño Events Latest Value Date

Niño 4

SST anomalies averaged over the NINO4 region 5°North-5°South; 160°East-150°West (western most of Niño indices). Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010. 0.25 Aug 2017

Niño 3.4

SST anomalies averaged over the NINO34 region 5°North-5°South;170-120°West. Total SSTs also available for this region. Correlates well with teleconnections to North America. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010. 0.03 Aug 2017

Niño 3

SST anomalies averaged over the NINO3 region 5°North-5°South;150°West-90°West. Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010. -0.17 Aug 2017

Niño 1.2

SST anomalies averaged over the NINO1 and NINO2 regions 0-10°South;90°West-80°West (eastern most of the Niña indices). Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010. -0.27 Aug 2017

TNI

Trans-Niño Index: Standardized Niño 1+2 minus the Niño 4 with a 5 month running mean applied (restandardized). It represents the gradient of the SST in the ENSO region of the tropical Pacific. Calculated from the Monthly HadISSTV1.1 dataset. -1.58 Jul 2017
These plots show time-series plots of the monthly values from 1948 to present for the set of ENSO indices.
Name Description Time Series Latest Value Units Latest dateGet Values

MEI

A multi-variate index of ENSO which uses SST and winds. It is calculated using the ICOADS dataset. Produced at NOAA/ESRL PSD. -0.45 std Sep 2017 Get

Niño 4

SST anomalies averaged over the NINO4 region 5°North–5°South; 160°East–150°West (western most of Nino indices). Total SSTs also available for this region. Calculated from the Monthly ERSST V4 (at NOAA/CPC). 0.07 CSep 2017 Get

Niño 3.4

SST anomalies averaged over the NINO34 region 5°North-5°South;170-120°West. Total SSTs also available for this region. Correlates well with teleconnections to North America. Calculated from the Monthly ERSST V4 (at NOAA/CPC). -0.43 C Sep 2017 Get

Niño 3

SST anomalies averaged over the NINO3 region 5°North–5°South; 150°West–90°West. Total SSTs also available for this region. Calculated from the Monthly ERSST V4 (at NOAA/CPC). -0.74 C Sep 2017 Get

Niño 1+2

SST anomalies averaged over the NINO1 and NINO2 regions 0-10°South; 90°West–80°West (eastern most of the Niña indices). Total SSTs also available for this region. Calculated from the Monthly ERSST V4 (at NOAA/CPC). -0.81 C Sep 2017 Get

ONI

Oceanic Niño Index: 3 month running mean of ERSST.v4 SST anomalies in the Niño 3.4 region (5°N–5°S, 120°&8211;170°W) Calculated from the ERSST V4 (at NOAA/CPC). -0.15 C Aug 2017 Get

BEST

Bivariate El Nino- Southern Oscillation Index: The Niño 3.4 SST and SOI are normalized and combined. SST is from the HadISST1.1 SOI is from NOAA/CPC. Produced at NOAA/ESRL PSD. -0.40 diff std Dec 2015 Get

SOI

Southern Oscillation Index: Difference between standardized Darwin and standardized Tahiti surface pressure values. It represents the atmospheric component of the ENSO. The sign is opposite that of the Nino indices and it is noisier than those indices. From NOAA/CPC 1.00 diff std Sep 2017 Get

TNI

Trans-Niño Index: Standardized Niño 1+2 minus the Niño 4 with a 5 month running mean applied (restandardized). It represents the gradient of the SST in the ENSO region of the tropical Pacific. Calculated from the Monthly HadISST1.1 dataset. -1.12 std Jun 2017 Get

PDO

Pacific Decadal Oscillation: leading principal component of monthly SST anomalies in the North Pacific Ocean, poleward of 20N (global SST mean removed). Calculated from the NOAA OISST V1 and V2 (U of Washington). 0.32 std Sep 2017 Get

PNA

Pacific NorthAmerican Pattern. The PNA is one of the most prominent modes of extratropical variability in the northern Hemisphere. This version is calculated at NOAA/CPC. It is based on EOF's calculated from monthly anomalies of 500mb height from the NCEP Reanalysis. -0.32 std Sep 2017 Get

OLR

Outgoing Longwave Radiation (OLR) area averages over the central equatorial Pacific (160°E–160°W). OLR is a good measure of convection. Negative OLR represents increased convention. Calculated at NOAA/CPC. 0.80 std Sep 2017 Get

Heat Content

Tropical Pacific integrated temperature anomalies (0-300m) 160°E-–0°W. Calculated at NOAA/CPC from the GODAS dataset. -0.57 degC Sep 2017 Get

200mb U

200mb Zonal Wind anomalies (2.5°S–2.5°N; 165°W–110°W). Calculated at NOAA/ESRL from the NCEP R1 dataset. -1.16 degC Sep 2017 Get

ESPI Precip Index

ENSO Precipitation Index. The index is based on rainfall anomalies in two rectangular areas, one in the eastern tropical Pacific (10°S-10°N, 160°E-100°W) and the other over the Maritime Continent (10°S-10°N, 90°E-150°E). The first step of the procedure involves moving a 10° by 50° block around each box; the minimum and maximum values of all possible blocks is obtained for each box and these are combined to estimate an El Niño precipitation index (EI) and a La Niña precipitation index (LI). The EI and LI are in turn combined to create the ESPI index. Finally, the ESPI index is normalized to have zero mean and unit standard deviation. Calculated at UMD. -0.47 sigma Nov 2016 Get
These plots show time-series plots of the monthly values from 1870 to present for the set of ENSO indices.
Name Description Time Series Latest Value Units Latest date Get Values

Niño 4

SST anomalies averaged over the NINO4 region 5°North-5°South; 160°East-150°West (western most of Nino indices). Total SSTs also available for this region. Calculated from the Monthly ERSST V4 (at NOAA/ESRL). 0.25 std Aug 2017 Get

Niño 3.4

SST anomalies averaged over the NINO34 region 5°North-5°South;170-120°West. Total SSTs also available for this region. Correlates well with teleconnections to North America. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010. 0.03 std Aug 2017 Get

Niño 3

SST anomalies averaged over the NINO3 region 5°North-5°South;150°West-90°West. Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010.

-0.17 std Aug 2017 Get

Niño 1+2

SST anomalies averaged over the NINO1 and NINO2 regions 0-10°South;90°West-80°West (eastern most of the Nina indices). Total SSTs also available for this region. Calculated from the Monthly NOAA ERSST V4 (at NOAA/ESRL). Climatology 1981-2010. -0.27 std Aug 2017 Get

TNI

Trans-Niño Index: Standardized Niño 1+2 minus the Niño 4 with a 5 month running mean applied (restandardized). It represents the gradient of the SST in the ENSO region of the tropical Pacific. Calculated from the Monthly HadISSTV1.1 dataset. -1.58 std Jul 2017 Get