Basin patterns of upper ocean warming for 1993–2009
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A previous study (Lyman et al., Nature 465:334–337, 2010) showed a robust warming signal of the global upper ocean (0–700 m). They examined several sources of uncertainty that contribute to differences among heat content estimations. However, their focus was limited to globally averaged estimation. This study presents the spatial pattern of the global heat content change based on observed gridded datasets (Levitus et al., Geophys Res Lett 36:L07608, 2009). The western Pacific, Atlantic, and Indian Oceans showed significant warming trends, whereas eastern Pacific and some areas of the Gulf Stream experienced negative trends during 1993–2009. Steady warming trend was obtained from the first EOF mode when El Nino and Southern Oscillation (ENSO)-related signals were removed. This result implies that the rapid increase in heat content of the upper ocean around 2000–2005 is not related to a sampling transition from XBT to Argo observations but is associated with a natural variability dominated by strong ENSO-related signals.
KeywordsHeat content Spatial pattern Steady warming ENSO-related signals
I acknowledge the publicly available database and research groups on heat content gridded data and the WOD 2009 by NODC, which helped make this study possible. I thank Dr. A. Rosati, G. A. Vecchi, and S. Zhang in Geophysical Fluid Dynamics Laboratory for their comments on the earlier version of this manuscript. I also appreciate two anonymous referees for insightful reviews of the manuscript.
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