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Low latitude western boundary currents (LLWBC) are western boundary currents that are close to the equator. Some examples of these include the Mindanao Current (MC), New Guinea Coastal Current (NGCC), North Brazil Current (NBC), the East India Current (EIC), and the East African Coastal Current (EACC).

LLWBCs are driven by the subtropical gyre and represent a closing of the Sverdrup Balance. Sea surface height gradients (a barotropic effect) and density gradients (a baroclinic effect) are important factors in determining their strengths. LLWBCs play a significant role in the cross-equatorial transport of mass, heat, and salt. They tend to bring relatively saltier water from subtropical basins into the relatively fresher tropical zones. The North Pacific system of LLWBCs is of particular interest due to its irregular topography, proximity to the ENSO, and influence on the tropical warm pool.

An aspect of LLWBCs that is important is their seasonality and their susceptibility to the influence of monsoons and ENSO. Both the East Indian Current in the Bay of Bengal and the New Guinea Coastal Current change direction depending on the monsoon. In the case of the East Indian Current (EIC), when there is a north-easterly monsoon the EIC is directed towards the south-west, and when there is a south-westerly monsoon it is directed towards the north-east.

LLWBCs tend to vary considerably with respect to the volume transported too. This has been observed in the Pacific in the case of the New Guinea Coastal Undercurrent, but also in the Indian Ocean. This has a lot to do with the El Nino Southern Oscillation.

LLWBCs in the North Pacific system serve as the source for the Indonesian Throughflow (ITF). Water entering the ITF is a mixture of southern and northern hemisphere water.

Subsurface flow
Thermocline flow of LLWBCs are also notable. In the Pacific region, it had been thought that the return flows for many of the currents in the Pacific LLWBC region simply ran counter to their surface flows. For instance, in the case of the Mindanao Current where there is a dominant south-directed, equator-ward flow, it was thought that the Mindanao Undercurrent (MUC) would be north-directed, poleward, and located precisely underneath the MC. As it turns out, what actually happens beneath the thermocline, i.e. at depths of approximately 500m is a little bit more complicated. Qiu et al found that at a large scale (>400 km), there was a more or less constant large MUC. However, at smaller scales, convergences driven by eastward zonal jets were found 7, 10, 13, and 18 degrees north respectively. So, at a small scale, there is an alternating pattern of poleward and equatorward flows in the MUC.

Mixing
Another aspect of interest for LLWBCs is mixing. Some authors have shown that LLWBC systems may be areas of high diapycnal mixing, that is, mixing across isopycnal lines (lines of constant density). With respect to a section taken across the Mindanao Eddy, others Apart from certain on the south and north flanks of the Mindanao Eddy where mixing is driven by velocity shear, the area around the Mindanao Current is a low mixing regime. The authors acknowledge that further experiments are necessary.

Climate Change
Others have examined the likely changes to LLWBC in the future. The future looks quite different for many western boundary currents. Transport along the Mindanao Current and North Brazil Current will become weaker, while transport along the Gulf of Papua Current and the New Guinea Coastal Undercurrent will intensify.