Journal of Oceanography

, Volume 71, Issue 1, pp 77–90 | Cite as

Climatology of hot events in the western equatorial Pacific

  • Anindya Wirasatriya
  • Hiroshi KawamuraEmail author
  • Teruhisa Shimada
  • Kohtaro Hosoda
Original Article


We investigated the climatology of hot events (HEs) in the western equatorial Pacific. HEs are characterized by well-organized high sea surface temperatures (SSTs). We proposed a method for identifying HEs using a space–time-dependent threshold with a minimum areal size of 2 × 106 km2, and with a duration (period) of >6 days. We thus identified 71 HEs from the optimally interpolated SST dataset during 2003–2011. Their mean duration, areal size, and amplitude were 18.14 days, 6.30 × 106 km2, and 0.33 °C, respectively. On average, the HEs developed more slowly than they decayed. They were distributed within the equatorial band to the subtropical Pacific (20°S–30°N), with an eastward extension to 150°W. In particular, the HEs occurred most frequently along the northern coasts of New Guinea and the Solomon Islands to 180°E. Seasonal variation in the HE distribution was observed: a northward shift during boreal summer and a southward shift during boreal winter. The distribution of HE occurrences corresponded to the climatological SST of the western Pacific warm pool. HEs occurred under conditions of low wind speeds (~2.56 m/s) and high levels of solar radiation (~225 W/m2). However, since the high levels of solar radiation occurred over the entire area of the western equatorial Pacific during HE periods, the low wind speed distribution became a key factor in the occurrence of HEs in the western equatorial Pacific. Seasonal shifts in wind speed and solar radiation were found to influence the seasonal shift in HE distribution.


High SST Hot event Merged SST Western Pacific warm pool 



Sea surface temperature


Hot event


New Generation Sea Surface Temperature version 2.0a



JRA-25/JCDAS data were made available by a cooperative research project of the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry. ISCCP-FD data were provided courtesy of the NASA Goddard Institute for Space Studies. The global ocean heat flux products were provided by the WHOI OAFlux project (, as funded by the NOAA Climate Observations and Monitoring (COM) program. TAO/TRITON buoy data were distributed by the TAO Project Office of NOAA/PMEL. NOAA_OI_SST_V2 data were provided by the NOAA/OAR/ESRL PSD (Boulder, CO, USA), via their website at Merged satellite and in situ data on global daily sea surface temperature were from the Japan Meteorological Agency (JMA), and are available at The first author thanks the Directorate General of Higher Education, Indonesian Republic, for a Ph.D. scholarship.


  1. Arking A, Ziskin D (1994) Relationship between clouds and sea surface temperatures in the western tropical Pacific. J Climate 7:988–1000Google Scholar
  2. Chongyin L, Mingquan M, Guangqing Z (1999) The variation of warm pool in the equatorial western Pacific and its impacts on climate. Adv Atmos Sci 16(3):378–394CrossRefGoogle Scholar
  3. Clement A, Seager R (1999) Climate and the tropical oceans. Am Meteorol Soc 12:3383–3401Google Scholar
  4. Clement AC, Seager R, Murtugudde R (2005) Why are there tropical warm pools? J Climate 18:5294–5310CrossRefGoogle Scholar
  5. Harweijer C, Seager R, Winton M, Clement A (2005) Why ocean heat transport warms the global mean climate. Tellus 57A:662–675CrossRefGoogle Scholar
  6. Hosoda K (2013) Empirical method of diurnal correction for estimating sea surface temperature at dawn and noon. J Oceanogr 69:631–646. doi: 10.1007/s10872-013-0194-4 CrossRefGoogle Scholar
  7. Kawai Y, Kawamura H, Takahashi S, Hosoda K, Murakami H, Kachi M, Guan L (2006) Satellite-based high-resolution global optimum interpolation sea surface temperature data. J Geophys Res 111:C06016. doi: 10.1029/2005JC003313 Google Scholar
  8. Kawamura H, Qin H, Ando K (2008) In-situ diurnal sea surface temperature variations and near-surface thermal structure in the tropical Hot Event of the Indo-Pacific warm pool. J Oceanogr 64:847–857CrossRefGoogle Scholar
  9. Kim ST, Yu JY, Lu MM (2012) The distinct behaviors of Pacific and Indian Ocean warm pool properties on seasonal and interannual time scales. J Geophys Res 117:D05128. doi: 10.1029/2011JD016557 Google Scholar
  10. Kurihara Y, Sakurai T, Kuragano T (2006) Global daily sea surface temperature analysis using data from satellite microwave radiometer, satellite infrared radiometer and in situ observations. Weather Serv Bull Sokkou-Jihou 73:S1–S18 (in Japanese)Google Scholar
  11. Lin CY, Ho CR, Zheng Q, Kuo NJ, Chang P (2011) Warm pool variability and heat flux change in the global oceans. Glob Planet Change 77:26–33CrossRefGoogle Scholar
  12. Onogi K, Tsutsui J, Koide H, Sakamoto M, Kobayashi S, Hatsushika H et al (2007) The JRA-25 reanalysis. J Meteor Soc Japan 85:369–432Google Scholar
  13. Pierrehumbert RT (2000) Climate change and the tropical Pacific: the sleeping dragon wakes. Proc Natl Acad Sci USA 97(4):1355–1358Google Scholar
  14. Qin H, Kawamura H (2009) Atmosphere response to a hot SST event in November 2006 as observed by AIRS instrument. Adv Space Res 44:395–400. doi: 10.1016/j.asr.2009.03.003 CrossRefGoogle Scholar
  15. Qin H, Kawamura H (2010) Air–sea interaction throughout the troposphere over a very high sea surface temperature. Geophys Res Let 37:1–4. doi: 10.1029/2009GL041685
  16. Qin H, Kawamura H, Kawai Y (2007) Detection of hot event in the equatorial Indo-Pacific warm pool using advanced satellite sea surface temperature, solar radiation, and wind speed. J Geophys Res 112:C07015. doi: 10.1029/2006JC003969 Google Scholar
  17. Qin H, Kawamura H, Sakaida F, Ando K (2008) A case study of the tropical hot event in November 2006 (HE0611) using a geostationary meteorological satellite and the TAO/TRITON mooring array. J Geophys Res 113:C08045. doi: 10.1029/2007JC004640 Google Scholar
  18. Ramanathan V, Collins W (1991) Thermodynamic regulation of ocean warming by cirrus clouds deduced from observations of the 1987 El Niño. Nature 351:27–32CrossRefGoogle Scholar
  19. Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Climate 15:1609–1625CrossRefGoogle Scholar
  20. Shinoda T, Hendon H, Glick J (1998) Intraseasonal variability of surface fluxes and sea surface temperature in the tropical western Pacific and Indian Oceans. J Climate 11:1685–1702CrossRefGoogle Scholar
  21. Thoron TG, Rosenthal Y, Bassinot F, Beaufort L (2005) Stable sea surface temperatures in the western Pacific warm pool over the past 1.75 million years. Nature 433:294–298CrossRefGoogle Scholar
  22. Waliser DE (1996) Formation and limiting mechanisms for very high sea surface temperature: linking the dynamics and the thermodynamics. J Clim 9:161–188Google Scholar
  23. Waliser DE, Graham NE (1993) Convective cloud systems and warm-pool sea-surface temperatures: coupled interactions and self-regulation. J Geophys Res 98(D7):12881–12893CrossRefGoogle Scholar
  24. Wallace JM (1992) Effect of deep convection on the regulation of tropical sea surface temperature. Nature 357:230–231CrossRefGoogle Scholar
  25. Webster PJ, Clayson CA, Curry JA (1996) Clouds, radiation, and the diurnal cycle of sea surface temperature in the tropical western Pacific. J Clim 9:1712–1730CrossRefGoogle Scholar
  26. Wilks DS (2006) Forecast verification. In: Statistical methods in the atmospheric sciences. Academic, San Diego, pp 260–277Google Scholar
  27. Wyrtki K (1989) Some thoughts about the west Pacific warm pool paper. In: Picaut J, Lukas R, Delcroix T (eds) Proceedings of the Western Pacific International Meeting and Workshop on TOGA COARE, held at Centre ORSTOM de Nouméa, New Caledonia, 24–30 May, 1989. Institut français de recherche scientifique pour le développement en coopération, Centre de Nouméa, Nouméa, pp 99–109Google Scholar
  28. Yan X-H, Ho CR, Zheng Q, Klemas V (1992) Temperature and size variabilities of the western Pacific warm pool. Science 258:1643–1645CrossRefGoogle Scholar
  29. Yu L, Weller RA (2007) Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005). Bull Am Meteor Soc 88:527–539Google Scholar
  30. Zhang Y-C, Rossow WB, Lacis AA, Oinas V, Mishchenko MI (2004) Calculation of radiative fluxes from the surface to top of atmosphere based on ISCCP and other global data sets: refinements of the radiative transfer model and the input data. J Geophys Res 109:1–27. doi: 10.1029/2003JD004457 Google Scholar

Copyright information

© The Oceanographic Society of Japan and Springer Japan 2014

Authors and Affiliations

  • Anindya Wirasatriya
    • 1
  • Hiroshi Kawamura
    • 1
    Email author
  • Teruhisa Shimada
    • 1
  • Kohtaro Hosoda
    • 1
  1. 1.Center for Atmospheric and Oceanic Studies, Graduate School of ScienceTohoku UniversitySendaiJapan

Personalised recommendations