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Acoustic Doppler Sonar Technologies ADCPs and DVLs

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Mozambique Channel. The LOCO project redeployed the For seasonal periods, modest changes in ? ow volumes were extensive mooring array several times. The full array was linked to wind-stress patterns over the Indian Ocean basin.

sustained for seven years and a reduced array even longer. At interannual time scales, changes much larger than sea- The upper 500 m contained the strongest currents. In the sonal variations were found. These swings in volume trans- initial array design, six of the moorings were topped with port were attributed to large-scale climate ? uctuations. The upward 75 kHz ADCPs from Teledyne RDI. On the western latter are identi? ed by a regional climate index—IOD (In- side of the Channel, moorings had near-bed ADCPs to see an dian Ocean Dipole).

Undercurrent, which is directed equatorward. Exposing the details of this subtle climate connection was

The data set spans many years with consistently impressive possible due to the long duration of the data set. Notably, a spatial coverage across the Mozambique Channel. As the lag of almost 12 months was found between changes in the available record lengthened, the Dutch scientists examined IOD climate index and corresponding variation in water vol- different facets of volume transport through the Channel. In umes supplied to the Agulhas Current.

particular, this longevity is needed to see links with remote current systems in equatorial and Indonesian regions.

Agulhas Current Time-Series

The researchers discerned that variability in the transport

Experiment (ACT): 2010—2013 could be sorted into three categories. For shorter time scales,

Farther south, another extensive moored array spanned the the recurring large eddies passing southward dominate

Agulhas Current from 2010 until 2013. This project was the changes in transport. These estimates became more statisti-

US Agulhas Current Time Series Experiment (ACT), led by cally reliable when based on the longer data record.

Fig. 2

Location of

LOCO moored array in



Credit: H. Ridderinkhof (NIOZ) 2006.

Marine Technology Reporter 57

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