Reviewing the Oceanic Niño Index (ONI) to Enhance Societal Readiness for El Niño’s Impacts

Abstract

NOAA’s Oceanic Niño Index (ONI) is used to record for historical purposes the occurrence and duration of El Niño episodes, based on the monitoring of sea surface temperatures (SSTs) in the central Pacific Ocean. The ONI is used to identify the onset of an above average SST threshold that persists for several months, encompassing both the beginning and end of an El Niño episode. The first appearance of an anomalous seasonal value of 0.5 °C suggests with a high probability that an El Niño could emerge, but for heightened warnings, one must wait for several months. In this article, we proposed that the ONI value of 0.7 °C identifies a tipping point at which the El Niño event becomes locked in, which can provide additional lead time for mitigative actions to be taken by societal decision makers. Our preliminary findings suggest that a first appearance of 0.7 °C value could serve as a credible marker of El Niño’s locked-in phase, which can provide additional credibility to the current 0.5 °C El Niño onset indicator for at-risk societies to get ready for El Niño’s foreseeable societal and ecological impacts.

Keywords

Advisory / Disasters / Early warning / El Niño / El Niño Southern Oscillation / ENSO / Hydrometeorological hazards / Oceanic Niño Index / ONI

References

[1] Barnston AG, Glantz MH, He Y. Predictive skill of statistical and dynamical climate models in SST forecasts during the 1997–98 El Niño episode and the 1998 La Niña onset. Bulletin of the American Meteorological Society, 1999, 80(2): 218-243

[2] Becker, E. 2015. March 2015 ENSO discussion: El Niño is here. ENSO Blog, 5 March 2015. https://www.climate.gov/news-features/blogs/enso/march-2015-enso-discussion-el-ni%C3%B1o-here. Accessed 29 Nov 2019.

[3] Berardelli, J. 2019. The El Nino has arrived: What does it mean for the weather? CBS News, 14 February 2019. https://www.cbsnews.com/news/el-nino-2019-weather-forecast-what-is-el-nino/. Accessed 1 Dec 2019.

[4] BOM (Bureau of Meteorology), Australian Government. n.d. Southern Oscillation Index—1993–2000. http://www.bom.gov.au/climate/current/soi-1993-2000.shtml. Accessed 25 Sept 2019.

[5] Caviedes CN. El Niño 1982–83. Geographical Review, 1984, 74(3): 267-290

[6] Chiodi, A.M., and D.E. Harrison. 2016. 2015–16 El Nino seasonal weather impacts from the OLR event perspective. Presented at the 41st NOAA Annual climate diagnostics and prediction workshop, 3–6 October 2016, Orono, Maine, USA. https://www.nws.noaa.gov/ost/climate/STIP/41CDPW/41cdpw-AChiodi.pdf. Accessed 13 Jan 2020.

[7] ENFEN (Peru’s Technical Committee that studies El Niño (Comité Técnico del Estudio Nacional del Fenómeno El Niño)). 2012. Operational definition of El Niño and La Niña events and its magnitudes on the Peru coast (Definiciόn operacional de los eventos El Niño y La Niña y sus magnitudes en la costa del Perú). http://www.imarpe.pe/imarpe/archivos/informes/imarpe_comenf_not_tecni_enfen_09abr12.pdf. Accessed 15 Nov 2018.

[8] GGWeather (Golden Gate Weather Services). 2019. El Niño and La Niña years and intensities: Based on the ONI. https://ggweather.com/enso/oni.htm. Accessed 25 Sept 2019.

[9] Glantz, M.H. (ed.). 2001. Once burned, twice shy? Lessons learned from the 1997–98 El Niño. Tokyo: United Nations University. https://collections.unu.edu/view/UNU:2374. Accessed 13 Jan 2020.

[10] Glantz, M.H., L. Naranjo, M.A. Baudoin, and I.J. Ramírez. 2018. What does it mean to be El Niño ready? Atmosphere 9(3): Article 94.

[11] Goddard L, Graham NE. El Niño in the 1990s. Journal of Geophysical Research, 1996, 102: 10423-10436

[12] IRI (International Research Institute for Climate and Society). n.d. El Niño and rainfall map. https://iridl.ldeo.columbia.edu/maproom/IFRC/FIC/ElNinoandRainfall.png. Accessed 12 Feb 2012.

[13] IRI (International Research Institute for Climate and Society). 2018. ENSO forecast: 2018 June quick outlook. https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-cpc_plume. Accessed 1 Dec 2019.

[14] Kessler WS, McPhaden MJ. Oceanic equatorial waves and the 1991–93 E1 Niño. Journal of Climate, 1995, 8: 1757-1774

[15] Lindsey, R. 2013. In watching for El Niño and La Niña, NOAA adapts to global warming. https://www.climate.gov/news-features/understanding-climate/watching-el-ni%C3%B1o-and-la-ni%C3%B1a-noaa-adapts-global-warming. Accessed 1 Jul 2019.

[16] McGregor, G.R., and K. Ebi. 2018. El Niño Southern Oscillation (ENSO) and health: An overview for climate and health researchers. Atmosphere 9(7): Article 282.

[17] McPhaden, M.J. 1990. TOGA-TAO and the 1991–93 El Niño-Southern Oscillation event. NOAA. https://www.pmel.noaa.gov/pubs/docs/mcph1401.html. Accessed 1 May 2019.

[18] McPhaden MJ, Zebiak SE, Glantz MH. ENSO as an integrating concept in earth science. Science, 2006, 314(5806): 1740-1745

[19] NOAA (National Oceanic and Atmospheric Administration). 2010. Cold and warm episodes by season. Spreadsheet previously available online at http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml. Accessed Aug 2010.

[20] NOAA (National Oceanic and Atmospheric Administration). 2019a. Nino regions. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/nino_regions.shtml. Accessed 23 Dec 2019.

[21] NOAA (National Oceanic and Atmospheric Administration). 2019b. Cold and warm episodes by season. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php. Accessed 30 Apr 2020.

[22] NOAA (National Oceanic and Atmospheric Administration). 2019c. ENSO alert system. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/enso-alert-readme.shtml. Accessed 29 Nov 2019.

[23] NOAA (National Oceanic and Atmospheric Administration). 2019d. ENSO diagnostic discussion archive. https://www.cpc.ncep.noaa.gov/products/expert_assessment/ENSO_DD_archive.php. Accessed 1 Dec 2019.

[24] Ramírez IJ, Grady SC, Glantz MH. Reexamining El Niño and cholera in Peru: A climate affairs approach. Weather, Climate, and Society, 2013, 5(2): 148-161

[25] Ropelewski CF, Halpert MS. Global and regional scale precipitation patterns associated with the El Niño Southern Oscillation. Monthly Weather Review, 1987, 115: 1606-1626

[26] Trenberth K, Hoar T. The 1990–1995 E1 Niño-Southern Oscillation event: Longest on record. Geophysical Research Letters, 1996, 23(1): 57-60

[27] Ubilava, D., and M. Abdolrahimi. 2019. The El Niño impact on maize yields is amplified in lower income teleconnected countries. Environmental Research Letters 14: Article 054008.

[28] Webb, E. 2019. Ensemble Oceanic Niño Index (ENS ONI). https://www.webberweather.com/ensemble-oceanic-nino-index.html. Accessed 15 Nov 2019.

[29] WMO (World Meteorological Organization). 2006. Catalogue of indices and definitions of El Niño and La Niña in operational use by WMO members. Geneva: WMO Commission for Climatology. http://www.wmo.int/pages/prog/wcp/wcasp/documents/ENSO-Indices-Catalogue_12062006.pdf. Accessed 13 Jan 2020.

[30] Zebiak SE, Orlove B, Munoz AG, Vaughan C, Hansen J, Troy T, Thomson MC, Lustig A Investigating El Niño-Southern Oscillation and society relationships. WIREs Climate Change, 2015, 6(1): 17-34