Mooring observations of equatorial currents in the upper 1000 m of the western Pacific Ocean during 2014

Wang, Fan; Wang, Jianbo; Guan, Cong; Ma, Qiang; Zhang, Dongxiao

doi:10.1002/2015jc011510

Cited by 32 publications

(31 citation statements)

References 25 publications

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“…Acoustic Doppler Current Profiler (ADCP) measurements for the upper 1,000 m of the ocean were available for the period of August 2014 to July 2016 at 0°, 142°E. This mooring deployed by IOCAS has one upward looking and one downward‐looking TRDI (Teledyne RD Instruments) 75 kHz ADCP mounted on the main float at the designed depth of 500 m (Song et al, ; Wang, Li, et al, ; Wang, Wang, et al, ). The accuracy of the 75 kHz ADCP is within ±5 mm/s in velocity magnitude and ±5° in direction.…”

Section: Methodsmentioning

confidence: 99%

“…In this study, we complement the TAO observation with mooring measurements at ~142°E during 2014–2016 conducted by Institute of Oceanology, Chinese Academy of Sciences (IOCAS; Wang, Li, et al, ; Wang, Wang, et al, ) and those of 1996–1998 by the Japan Marine Science and Technology Center (JAMSTEC; Kuroda, ; Matsuura, ; Ueki, ), which allows us to provide a comprehensive comparison of the ocean current ISVs during the two periods and assess their contributions to the two super El Niño events. This task is challenging owing to the discontinuity in space and time of in situ ocean current measurements, and therefore, we also employ ocean reanalysis data to aid the analysis.…”

Section: Introductionmentioning

confidence: 99%

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Contrasting Intraseasonal Variations of the Equatorial Pacific Ocean Between the 1997–1998 and 2015–2016 El Niño Events

Lyu

Tang

et al. 2018

Geophysical Research Letters

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Oceanic intraseasonal variability (ISV) plays a vital role in the initiation and development of El Niño events. Mooring observations reveal contrasting characteristics of upper-ocean zonal current ISV during different El Niño events. Compared to the 1997-1998 event, ISV of the 2015-2016 event was significantly weaker (by around 30-50%) over the equatorial Pacific basin, and the variability maximum was shifted to the east (~160°E). These differences can be largely explained by wind forcing features. ISV of surface winds in 2015 is overall weaker than in 1997. Intraseasonal westerly wind bursts in 1997 occurred near the western boundary and originated from the Indian Ocean, whereas in 2015, perturbations were mainly propagated from the northeast Pacific and achieved the peak power at~160°E of the equator. These changes are likely associated with the decadal warming of the northeast subtropical Pacific and weakening of the Indian Ocean intraseasonal oscillation.Plain Language Summary Sea surface warmings of strong El Niño events are usually triggered by intraseasonal oscillations prior to the events. Particularly, intraseasonal eastward ocean currents generated by westerly wind bursts carry the warm water of the western Pacific warm pool to the central Pacific and contribute to the surface warming. In this paper, we compare the intraseasonal zonal current variations during two strong El Niño events, namely, the 1997-1998 and 2015-2016 events. Although the two El Niño events were of comparable strengths, intraseasonal variations in 1997 were stronger than those in 2015 by 3050%. These differences can be largely explained by the contrasting features of wind forcing. Intraseasonal oscillations were originated from the Indian Ocean in 1997, whereas those in 2015 were mainly from the northeast subtropical Pacific. The varying origin is likely associated with the warming of the northeast subtropical Pacific and weakened Indian Ocean intraseasonal oscillation during recent years.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Contrasting Intraseasonal Variations of the Equatorial Pacific Ocean Between the 1997–1998 and 2015–2016 El Niño Events

Lyu

Tang

et al. 2018

Geophysical Research Letters

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“…The zonal circulation in the equatorial Pacific, Atlantic, and Indian Oceans differs in several aspects, resulting from a variety of spatial and temporal scales and a complex pattern of mean zonal currents and countercurrents (e.g., Brandt et al, ; Cane & Moore, ; Chen et al, ; Duan et al, ; Han et al, ; Jensen, ; Nagura & McPhaden, ; Philander & Chao, ; Rao et al, ; D. Wang et al, ; F. Wang et al, ). These rich flow structures extend from the upper layers (0–200 m) to middepths (200–1,500 m), where earlier studies have documented the oceanic dynamic response to atmospheric forcing (Eriksen, ; Firing, ; Luyten & Swallow, ; Wyrtki, ; Youngs & Johnson, ).…”

Section: Introductionmentioning

confidence: 99%

“…In the equatorial Pacific and Atlantic Oceans, the middepth zonal currents beneath the pycnocline are equatorially trapped and transient, with strong annual variability (Brandt & Eden, ; Fischer & Schott, ; Gouriou et al, ; F. Wang et al, ). They are associated with surface wind forcing and have pronounced vertical phase propagation.…”

Section: Introductionmentioning

confidence: 99%

Vertical Propagation of Middepth Zonal Currents Associated With Surface Wind Forcing in the Equatorial Indian Ocean

et al. 2018

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The vertical propagation of middepth (200-1,500 m) zonal velocity in the equatorial Indian Ocean (EIO) and its relationship with surface wind forcing are investigated. We focus on semiannual time scales, using in situ mooring observations and an oceanic reanalysis product that can reasonably well reproduce the structure and magnitude of the observed middepth zonal velocity in the EIO. The pronounced semiannual cycle in observed middepth zonal currents indicates a clear upward phase propagation with particularly robust signatures at depths of 500-1,000 m between 3°S to 3°N, 70 to 85°E. The main characteristics of the middepth currents are consistent with vertically propagating first-meridional-mode Rossby wave at semiannual period. Theory suggests that equatorial Kelvin waves, forced by zonal wind variations in the western half of the basin, transfer energy downward and eastward, reflecting into Rossby waves at the eastern boundary. These reflected Rossby waves transfer energy downward and westward, contributing greatly to observed phase propagation at middepths in the EIO.

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“…Opposite-direction undercurrents below both the Kuroshio and MC (e.g., Figure 6) converge to feed eastward subsurface jets (Qiu et al, 2013;Cravatte et al, 2017); the northward Mindanao Undercurrent also carries intermediate water from the South Pacific into the northern hemisphere (Qu and Lindstrom, 2004; Figure 5). Strong intraseasonal variability of these undercurrents has been identified from subsurface moorings (e.g., Wang et al, 2016). Recirculations offshore of the LLWBCs and the presence of both permanent and transient eddies complicate the understanding of current connectivity and blur the boundaries that define the LLWBC transport itself.…”

Section: North Pacific Low Latitude Western Boundary Currentmentioning

confidence: 99%

Tropical Pacific Observing System

Smith¹,

Kessler

Cravatte

et al. 2019

Front. Mar. Sci.

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Tropical Pacific Observing System equatorial cold tongue dynamics, the oxygen minimum zone and the seasonal double Intertropical Convergence Zone. A pilot program building on existing networks is envisaged, complemented by a process study of the East Pacific ITCZ/warm pool/cold tongue/stratus coupled system. The sustainability of TPOS depends on effective and strong collaborative partnerships and governance arrangements. Revisiting regional mechanisms and engaging new partners in the context of a planned and systematic design will ensure a multipurpose , multi-faceted integrated approach that is sustainable and responsive to changing needs.

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Mooring observations of equatorial currents in the upper 1000 m of the western Pacific Ocean during 2014

Abstract: Time-depth variations of the equatorial currents over the upper 1000 m depth in the western Pacific Ocean were directly measured by acoustic Doppler current profiler moorings at 28N,

Cited by 32 publications

References 25 publications

Contrasting Intraseasonal Variations of the Equatorial Pacific Ocean Between the 1997–1998 and 2015–2016 El Niño Events

Contrasting Intraseasonal Variations of the Equatorial Pacific Ocean Between the 1997–1998 and 2015–2016 El Niño Events

Vertical Propagation of Middepth Zonal Currents Associated With Surface Wind Forcing in the Equatorial Indian Ocean

Tropical Pacific Observing System

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