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Observed and Expected Changes to the Tropical Pacific Ocean

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Observed and Expected Changes to the Tropical Pacific Ocean Photo: Bruno Marty / IRD Chapter 3 Observed and expected changes to the tropical Pacific Ocean Alexandre S Ganachaud, Alex Sen Gupta, James C Orr, Susan E Wijffels, Ken R Ridgway, Mark A Hemer, Christophe Maes, Craig R Steinberg, Aline D Tribollet, Bo Qiu and Jens C Kruger ‘The oceans are warming.’ (Bindoff et al. 2007)i L %LQGRIIHWDO 2EVHUYDWLRQV2FHDQLFFOLPDWHFKDQJHDQGVHDOHYHO,Q66RORPRQ'4LQ 00DQQLQJ=&KHQ00DUTXLV.%$YHU\W07LJQRUDQG+/0LOOHU HGV &OLPDWH &KDQJH 7KH3K\VLFDO6FLHQFH%DVLV&RQWULEXWLRQRI:RUNLQJ*URXS,WRWKH)RXUWK$VVHVVPHQW5HSRUWRI WKH,QWHUJRYHUQPHQWDO3DQHORQ&OLPDWH&KDQJH&DPEULGJH8QLYHUVLW\3UHVV&DPEULGJH8QLWHG .LQJGRPDQG1HZ<RUN8QLWHG6WDWHVRI$PHULFDSS² 101 Contents Page 3.1 Introduction 103 3.1.1 Use of climate simulations 104 3.2 Features of the tropical Pacific Ocean 105 3.2.1 Large-scale currents 105 3.2.2 Ocean temperature 110 3.2.3 Ocean eddies 120 3.2.4 Nutrient supply 123 3.2.5 Dissolved oxygen 127 3.2.6 Ocean acidification 129 3.2.7 Wave height 131 3.2.8 Sea level 135 3.2.9 Coastal circulation and island effects 137 3.3 Observed and projected changes in the tropical Pacific Ocean 141 3.3.1 Large-scale currents 141 3.3.2 Ocean temperature 143 3.3.3 Ocean eddies 149 3.3.4 Nutrient supply 150 3.3.5 Dissolved oxygen 157 3.3.6 Ocean acidification 159 3.3.7 Wave height 163 3.3.8 Sea level 164 3.3.9 Coastal circulation and island effects 167 3.4 Summary of present-day ocean features, and observed and projected changes 169 3.5 Recommendations to reduce uncertainties in projecting future changes to the tropical Pacific Ocean 172 3.5.1 SPCZ and ENSO 172 3.5.2 Integrating biogeochemical and physical models 173 3.5.3 Dynamical downscaling 173 3.5.4 Long-term observations and monitoring 173 References 176 Appendix 188 102 CHAPTER 3 3.1 Introduction 7KHÀVKDQGLQYHUWHEUDWHVKDUYHVWHGIURPWKHWURSLFDO3DFLÀF2FHDQDQGWKHFRDVWDO ZDWHUVRIWKHUHJLRQDQGWKHHFRV\VWHPVWKDWVXSSRUWWKHVHVSHFLHVDUHLQÁXHQFHG 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