Impacts of Physical and Biological Processes on Spatial and Temporal Variability of Particulate Organic Carbon in the North Pacific Ocean during 2003–2017

Abstract

The North Pacific Ocean is a significant carbon sink region, but little is known about the dynamics of particulate organic carbon (POC) and the influences of physical and biological processes in this region at the basin scale. Here, we analysed high-resolution surface POC data derived from MODIS-Aqua during 2003–2017, together with satellite-derived sea surface chlorophyll and temperature (SST). There are large spatial and temporal variations in surface POC in the North Pacific. Surface POC is much lower in the subtropical region (<50 mg m−3) than in the subarctic region (>100 mg m−3), primarily resulting from the south-to-north variability in biological production. Our analyses show significant seasonal and interannual variability in surface POC. In particular, there is one peak in winter-spring in the western subtropical region and two peaks in late spring and fall in the western subarctic region. Surface POC is positively correlated with chlorophyll (r = ~1) and negatively correlated with SST (r = ~−0.45, P < 0.001) south of 45°N, indicating the strong influence of physically driven biological activity on the temporal variability of POC in the subtropical region. There is a significantly positive but relatively lower correlation coefficient (0.6–0.8) between POC and chlorophyll and an overall non-significantly positive correlation between POC and SST north of 45°N, reflecting the reduction in the POC standing stock due to the fast sinking of large particles. The climate modes of the Pacific Decadal Oscillation, El Niño–Southern Oscillation and North Pacific Gyre Oscillation have large impacts on POC in various seasons in the subtropical region and weak influences in the subarctic region. Surface POC was anomalously high after 2013 (increased by ~15%) across the basin, which might be the result of complex interactions of physical and biological processes associated with an anomalous warming event (the Blob).

Decreases in encounter rate of endangered Northeast Pacific humpback whales in Southern Costa Rica: Possible changes in migration pattern due to warming events

“…The monthly values of the PDO, as well as the monthly anomalies of SST show a warming period from 2013, which continued until 2017. This warming period, in addition to having a large temporal scale, also had a great spatial scope (Menne et al, 2018;Yu et al, 2019). It is possible that presence of warmer conditions recorded in intermediate latitudes (Mexican coasts) could have favored humpback whales in finding thermally favorable areas for calving and could be one of the causes of decreases in the encounter rates in Costa Rica (Cavole et al, 2016;Robinson, 2016).…”

Variations of chlorophyll-a and particulate organic carbon in the Yellow-Bohai Sea: in response to the Typhoon Lekima event

“…The POC:Chl-a ratio is often used to indicate the contribution of phytoplankton carbon to total POC in seawaters (Hung et al 2010;Yu et al 2019). Clearly, POC:Chl-a ratio was lower in nearshore waters (~ 50-100) than in offshore waters (> 150) in both non-typhoon years and 2019 (Fig.…”

Latitudinal-dependent emergence of phytoplankton seasonal blooms in the Kuroshio Extension

“…The SCC at lower latitudes of the KE region generally only peaks in late winter or early spring (i.e., SCC unimodality, Yoo et al, 2008), which is predominantly determined by nutrient availability. At higher latitudes, the combined effect of the nutrient and light leads to the spring and fall blooms of SCC (i.e., SCC bimodality, Kim et al, 2007;Yoo et al, 2008;Matsumoto et al, 2014;Yu et al, 2019). The diagram of seasonal change in the nutrient and light availability has been schematically described to shape the unimodality/bimodality of SCC (Lalli and Parsons, 2004), but our knowledge of their transition latitudes and the quantitative role of the nutrient and light in this specific region is fragmented.…”