Oxidation of iron and manganese ions is predominant in the oxygen-rich deep western boundary current (DWBC) within the Pacific Ocean. By the faster removal of particulate iron hydroxide and manganese oxide, densities of the particulate matters are considered to be lower in the DWBC than the interior region. To detect the density variation of suspended particles between the DWBC and interior regions, we analyzed echo intensity (EI) measured in the western North Pacific by hydrographic casts with a 300 kHz lowered acoustic Doppler current profiler (LADCP) in a whole water column. At depths greater than 3000 m (~ 3000 dbar), EI is almost uniformly low between 12°N and 30°N but peaks sharply from 30°N to 35°N to a maximum north of 35°N. EI is found to be anomalously low in the DWBC compared to the background distribution. The DWBC pathways are identifiable by the low EI and high dissolved oxygen concentration. EI data by LADCPs and other acoustic instruments may be used to observe the temporal variations of the DWBC pathways.

中文翻译：

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用降低的多普勒电流剖面仪测得的回波强度监测北太平洋西部的深西部边界电流

铁和锰离子的氧化主要发生在太平洋中富氧的深西部边界电流（DWBC）中。通过更快地去除颗粒状的氢氧化铁和氧化锰，DWBC中的颗粒物密度被认为比内部区域要低。为了检测DWBC和内部区域之间悬浮颗粒的密度变化，我们分析了北太平洋西部通过水文铸模在整个水柱中使用300 kHz降低的多普勒电流剖面仪（LADCP）测得的回波强度（EI）。在深度大于3000 m（〜3000 dbar）时，EI在12°N和30°N之间几乎一致地较低，但从30°N到35°N到35°N的最大北峰急剧下降。与背景分布相比，在DWBC中发现EI异常低。DWBC途径可通过低EI和高溶解氧浓度来识别。LADCP和其他声学仪器的EI数据可用于观察DWBC路径的时间变化。