Journal of Oceanography

, Volume 71, Issue 5, pp 541–556 | Cite as

Impact of downward heat penetration below the shallow seasonal thermocline on the sea surface temperature

  • Shigeki Hosoda
  • Masami Nonaka
  • Tomohiko Tomita
  • Bunmei Taguchi
  • Hiroyuki Tomita
  • Naoto Iwasaka
Special Section: Original Article “Hot Spots” in the Climate System: New Developments in the Extratropical Ocean-Atmosphere Interaction Research


Observational data are used to investigate summer heat penetration into the subsurface ocean in order to quantify the heat capacity of the upper ocean with respect to surface heat exchange. Sea surface temperature is strongly modulated by the change in heat capacity, which could influence the overlying atmosphere and hence trigger climate variations, even during the warming season, when the ocean has been regarded as being rather passive. Few studies have focused on the heat exchange process in surface and subsurface layers because of the existence of a strong seasonal thermocline at the bottom of thin summer mixed layers (ML). By introducing the concept of the heat penetration depth (HPD), defined as the depth to which the downward net heat flux (Q net) distinctly penetrates, we here characterize the heat capacity in terms of the heat content above the HPD using a simple, one-dimensional vertical model during the warming season. Seasonal changes in the HPD indicate that the thermal effects of Q net gradually penetrate below the shallow seasonal thermocline due to vertical eddy diffusivity. Downward heat penetration into the layer below the shallow seasonal thermocline occurs widely throughout the North Pacific, and two-thirds of Q net penetrates below the ML. In a hypothetical analysis of the case where the observed Q net accumulates only within the ML, the change in SST is unrealistically larger than that of the observed SST. These results indicate that heat penetration plays a crucial role in climate variations during the warming season.


Heat capacity Seasonal variability North Pacific Argo J-OFURO2 Air–sea interaction 



We thank the participants in the regular meetings of the Mid- and High-Latitude Climate Predictability Research Team for their useful discussions. Members of the data management team of the Strategic Ocean Monitoring Research Team of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) helped with the use of Argo float data and the refinement of the dataset. Argo float data were obtained from the GDAC websites at and We obtained heat flux data from the J-OFURO2 website at This work was supported by Grants-in-Aid for Scientific Research (22106006, 22510023, 21540458, 24540476, and 23340139) from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan.


  1. Akima H (1970) A new method for interpolation and smooth curve fitting based on local procedures. J Assoc Comput Mech 17:589–603CrossRefGoogle Scholar
  2. Alexander MA, Deser C (1995) A mechanism for the recurrence of wintertime midlatitude SST anomalies. J Phys Oceanogr 25:122–137CrossRefGoogle Scholar
  3. Alexander MA, Deser C, Timlin MS (1999) The reemergence of SST anomalies in the North Pacific Ocean. J Clim 12:2419–2433CrossRefGoogle Scholar
  4. Alexander MA, Timlin MS, Scott JD (2001) Winter to-winter recurrence of sea surface temperature, salinity and mixed layer depth anomalies. Prog Oceanogr 49:41–61CrossRefGoogle Scholar
  5. Antonov JA, RA Locarnini, Boyer TP, Garcia HE, Mishonov A (2006) World ocean atlas 2005, vol. 2: salinity. Ed. S. Levitus. NOAA Atlas NESDIS 62. US Government Printing Office, Washington, DCGoogle Scholar
  6. Argo Data Management Team (2002) Report of the Third Argo Data Management Meeting. Marine Environmental Data, Ottawa, p 42Google Scholar
  7. Argo Data Management Team (2012) Argo user’s manual, ver. 2.4, p 85. Accessed at
  8. Argo Science Team (2001) Argo: the global array of profiling floats. In: Koblinsky CJ, Smith NR (eds) Observing the oceans in the 21st century. GODAE Project Office, Bureau of Meteorology, Melbourne, pp 248–258Google Scholar
  9. D’Asaro EA, Eriksen CC, Levine MD, Niller P, Paulson CA, Meurs PV (1995) Upper ocean internal currents forced by a strong storm. Part I: data and comparisons with linear theory. J Phys Oceanogr 25:2909–2936CrossRefGoogle Scholar
  10. de Boyer Montegut C, Madec G, Fischer AS, Lazar A, Iudicone D (2004) Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J Geophys Res 109:C12003. doi: 10.1029/2004JC002378 CrossRefGoogle Scholar
  11. Deser C, Alexander MA, Timlin MT (1996) Upper ocean thermal variations in the North Pacific during 1970–1991. J Clim 9:1840–1855CrossRefGoogle Scholar
  12. Deser C, Alexander MA, Timlin MT (2003) Understanding the persistence of sea surface temperature anomalies in midlatitudes. J Clim 16:57–72CrossRefGoogle Scholar
  13. Farewell CW, Bradley EF, Hare JE, Grachev AA, Edson JB (2003) Bulk parameterization of air-sea fluxes: updates and verification for the COARE algorithm. J Clim 16:571–591CrossRefGoogle Scholar
  14. Frankignoul C (1985) Sea surface temperature anomalies, planetary waves and air-sea feedback in middle latitudes. Rev Geophys 23:357–390CrossRefGoogle Scholar
  15. Frankignoul C, Hasselmann K (1977) Stochastic climate models. Part 2. Application to sea-surface temperature variability and thermocline variability. Tellus 29:289–305CrossRefGoogle Scholar
  16. Gent PR, Yeager SG, Neale RB, Levitus S, Bailey DA (2010) Improvements in a half degree atmosphere/land version of the CCSM. Clim Dyn 34:819–833. doi: 10.1007/s00382-009-0614-8 CrossRefGoogle Scholar
  17. Hack JJ, Caron JM, Danabasoglu G, Oleson KW, Bitz C, Truesdale JE (2006) CCSM–CAM3 climate simulation sensitivity to changes in horizontal resolution. J Clim 19:2267–2289. doi: 10.1175/2009JCLI3053.1 CrossRefGoogle Scholar
  18. Hall MM, Bryden L (1982) Direct estimates and mechanisms of ocean heat transport. Deep Sea Res 29(3A):339–359CrossRefGoogle Scholar
  19. Hanawa K, Toba Y (1981) Terms governing temperature and thickness of the oceanic mixed layer and their estimates for sea area south of Japan. Tohoku Geophys J (Sci Rep Tohoku Univ Ser 5) 28:161–173Google Scholar
  20. Hosoda S, Ohira T, Nakamura T (2008) A monthly mean dataset of global oceanic temperature and salinity derived from Argo float observations. JAMSTEC Rep Res Dev 8:47–59CrossRefGoogle Scholar
  21. Hosoda S, Ohira T, Sato K, Suga T (2010) Improved description of global mixed-layer depth using Argo profiling floats. J Oceanogr 66(6):773–787CrossRefGoogle Scholar
  22. Kosaka Y, Nakamura H (2006) Structure and dynamics of the summertime Pacific–Japan (PJ) teleconnection pattern. Quart J Roy Meteor Soc 132:2009–2030Google Scholar
  23. Kubota M, Iwasaka N, Kizu S, Kondo M, Kutsuwada K (2002) Japanese ocean flux data sets with use of Remote Sensing Observations (J-OFURO). J Oceanogr 58:213–225. doi: 10.1023/A:1015845321836 CrossRefGoogle Scholar
  24. Liu Q, Xie S-P, Li L, Maximenko NA (2005) Ocean thermal advection effect on the annual range of sea surface temperature. Geophys Res Lett 32:L24604. doi: 10.1029/2005GL024493 CrossRefGoogle Scholar
  25. Locarnini RA, A Mishonov, Antonov JA, Boyer TP, Garcia HE (2006) World ocean atlas 2005, vol. 1: temperature. NOAA Atlas NESDIS 61. US Government Printing Office, Washington, DCGoogle Scholar
  26. Moisan JR, Niiler PP (1998) The seasonal heat budget in the North Pacific, net heat flux and heat storage rates (1950–1990). J Phys Oceanogr 28:401–420CrossRefGoogle Scholar
  27. Namias J, Born RM (1970) Temporal coherence in North Pacific sea-surface temperature patterns. J Geophys Res 75:5952–5955CrossRefGoogle Scholar
  28. Namias J, Born RM (1974) Further studies of temporal coherence in North Pacific sea surface temperature. J Geophys Res 79:797–798CrossRefGoogle Scholar
  29. Nitta T (1987) Convective activities in the tropical western Pacific and their impact on the Northern Hemisphere summer circulation. J Meteor Soc Japan 65:373–390Google Scholar
  30. Paulson CA, Simpson JJ (1977) Irradiance mesurements in the upper ocean. J Phys Oceanogr 7:952–956CrossRefGoogle Scholar
  31. Qiu B (2000) Interannual variability of the Kuroshio Extension System and its impact on the wintertime SST field. J Phys Oceanogr 30:1486–1502Google Scholar
  32. Qiu B, Hacker P, Chen S, Donohue KA, Watts DR (2006) Observations of the subtropical mode water evolution from the Kuroshio Extension System study. J Phys Oceanogr 36:457–472Google Scholar
  33. Rossow WB, Schiffer RA (1991) ISCCP cloud data products. Bull Am Meteor Soc 72:2–20CrossRefGoogle Scholar
  34. Sugimoto S, Hanawa K (2005) Remote reemergence areas of winter sea surface temperature anomalies in the North Pacific. Geophys Res Lett 32:L01606. doi: 10.1029/2004GL021410 Google Scholar
  35. Tomita T, Nonaka M (2006) Upper-ocean mixed layer and wintertime sea surface temperature anomalies in the North Pacific. J Clim 19:300–307CrossRefGoogle Scholar
  36. Tomita T, Xie S-P, Nonaka M (2002) Estimates of surface and subsurface forcing for decadal sea surface temperature variability in the mid-latitude North Pacific. J Meteor Soc Japan 80:1289–1300Google Scholar
  37. Tomita H, Kubota M, Cronin MF, Iwasaki S, Konda M, Ichikawa H (2010a) An assessment of surface heat fluxes from J-OFURO2 at the KEO and JKEO sites. J Geophys Res 115:C03018. doi: 10.1029/2009JC005545 Google Scholar
  38. Tomita T, Nonaka M, Yamaura T (2010b) Interannual variability in the subseasonal northward excursion of the Baiu front. Int J Clim 30:2205–2216CrossRefGoogle Scholar
  39. Ueda H, Ohba M, Xie S-P (2009) Important factors for the development of the Asian-Northwest Pacific Summer Monsoon. J Clim 22:649–669CrossRefGoogle Scholar
  40. UNESCO (1981) Background papers and supporting data on the Practical Salinity Scale, 1978. UNESCO Tech Pap Mar Sci 37:1–144Google Scholar
  41. Wahl S, Latif M, Park W, Keenlyside N (2009) On the Tropical Atlantic SST warm bias in the Kiel climate model. Clim Dyn 36:891–906. doi: 10.1007/s00382-009-0690-9
  42. Yu L, Jin X, Weller RA (2008) Multidecade global flux datasets from the objectively analyzed air-sea fluxes (OAFlux) project: latent and sensible heat fluxes, ocean evaporation, and related surface meteorological variables. OAFlux Project Tech Rep OA-2008-01. Woods Hole Oceanographic Institution, Woods HoleGoogle Scholar
  43. Zhang H-M, Bates JJ, Reynolds RW (2006a) Assessment of composite global sampling: sea surface wind speed. Geophys Res Lett 33:L17714. doi: 10.1029/2006GL027086 CrossRefGoogle Scholar
  44. Zhang H-M, Reynolds RW, Bates JJ (2006) Blended and gridded high resolution global sea surface wind speed and climatology from multiple satellites: 1987–present. In: American Meteorological Society 2006 Annual Meeting, Atlanta, GA, USA, 29 Jan–2 Feb 2006, paper #P2.23Google Scholar

Copyright information

© The Oceanographic Society of Japan and Springer Japan 2015

Authors and Affiliations

  • Shigeki Hosoda
    • 1
  • Masami Nonaka
    • 2
  • Tomohiko Tomita
    • 3
  • Bunmei Taguchi
    • 2
  • Hiroyuki Tomita
    • 4
  • Naoto Iwasaka
    • 5
  1. 1.Research and Development Center for Global ChangeJapan Agency for Marine–Earth Science and TechnologyYokosukaJapan
  2. 2.Application LaboratoryJapan Agency for Marine–Earth Science and TechnologyYokohamaJapan
  3. 3.Graduate School of Science and TechnologyKumamoto UniversityKumamotoJapan
  4. 4.Hydrospheric Atmospheric Research CenterNagoya UniversityNagoyaJapan
  5. 5.Faculty of Marine TechnologyTokyo University of Marine Science and TechnologyTokyoJapan

Personalised recommendations