Peng Xiu

Xiamen University | XMU · State Key Laboratory of Marine Environmental Science

The North Pacific Subtropical Gyre (NPSG) is an oligotrophic environment where a number of mesoscale eddies occur. With continuous measurements from Biogeochemical‐Argo (BGC‐Argo) floats, we showed that mesoscale eddies can significantly affect the subsurface chlorophyll maximum (SCM) and subsurface biogenic particles. Different responses of the SC...

The impact of atmospheric deposition on deep‐ocean carbon export in the subtropical Northwest Pacific remains poorly evaluated. Using sediment trap data and a newly improved biogeochemical model, we show that iron deposition in winter and spring and nitrogen deposition in summer and fall are important drivers for the seasonal variability of deep‐oc...

Plain Language Summary Phytoplankton growth requires both light and nutrients. In most open oceans, the vertical distribution of the chlorophyll‐a concentration generally is a maximum at a subsurface depth because of nutrient depletion in surface waters and inadequate light at depth. We took advantage of the continuous observations from autonomous...

Oceanic submesoscale processes are ubiquitous in the North Pacific Subtropical Gyre (NPSG), where the biological carbon pump is generally ineffective. Due to difficulties in collecting continuous observations, however, it remains uncertain whether episodic submesoscale processes can drive significant changes in particulate organic carbon (POC) expo...

Plain Language Summary Iron is a critical trace element for the photosynthesis and nitrogen fixation of phytoplankton in the ocean. In North Pacific Subarctic region, although there is plenty of nitrate, the growth of phytoplankton is limited due to the lack of iron. In the North Pacific Subtropical Gyre (NPSG), nutrient supply to the surface is re...

The variability of chlorophyll (Chla) in the Southern Tropical Indian Ocean (STIO) is not fully understood. This study utilized biogeochemical Argo (BGC‐Argo) and satellite observations to investigate the seasonal Chla variations in the upper layer (above 200 m) and their relationships to physical dynamics. The results indicate the existence of a w...

A record‐breaking marine heatwave (MHW) occurred in the South China Sea (SCS) during the summer of 2020, causing substantial ecological impacts, while its influence on phytoplankton dynamics remains unknown. Here we employed a regionally optimized physical‐biogeochemical model to examine the phytoplankton response to this event. An analysis of the...

During the period from 25 August 2012 to 11 December 2013, five typhoons were tracked passing by an observation station near the Xisha Islands in the northern South China Sea (NSCS). An analysis of the temperature observations revealed that the lower ocean layer (below the thermocline) experiences warming prior to the typhoon’s arrival. A three-dim...

Although previous studies suggest that the surface quasigeostrophy (SQG) theory is practically applicable for subsurface reconstruction from sea surface observations, they mostly examine the reconstructability of density but seldom evaluate the velocities. Meanwhile, these studies all focus on the regions of energetic kinetic energy, and observatio...

Subtropical gyres cover 26%–29% of the world's surface ocean and are conventionally regarded as ocean deserts due to their permanent stratification, depleted surface nutrients, and low biological productivity. Despite tremendous advances over the past three decades, particularly through the Hawaii Ocean Time‐series and the Bermuda Atlantic Time‐ser...

Nutrient stoichiometry (e.g., nitrate + nitrite to soluble reactive phosphorus, refer to N + N/SRP, N/P hereafter) governs growth, competition and niche partitioning of phytoplankton in the illuminated oceans. The N/P, however, varies widely across the ocean and the underlying mechanisms remain unclear. Here, we report direct observations of signif...

An unprecedented warm sea surface temperature (SST) anomaly event, namely, the Blob, occurred in the northeast Pacific during the winter (October-January) of 2013/2014, causing substantial economic and ecological impacts. Here, we explore the driving forces of the Blob from both atmospheric and oceanic perspectives and show that the Blob primarily...

The South China Sea (SCS) is the largest semienclosed marginal sea in the western Pacific. The advective supply of dissolved organic carbon (DOC) from the open ocean to the SCS influences its carbon cycle and biogeochemical processes. However, quantitative studies of DOC exchange across different straits and the shelf to the SCS are particularly li...

Typhoon Merbok passed through the northern South China Sea and landed near the Pearl River Estuary in June 2017. Field observations showed that the chlorophyll‐a (Chla) concentration in the bottom/subsurface chlorophyll maximum (BCM/SCM) layer decreased in both nearshore and offshore regions after Merbok. In addition, the BCM/SCM layer became shall...

Plain Language Summary The formation and export of Antarctic Intermediate Water (AAIW) strongly influence the global climate system by redistributing heat, freshwater, carbon, and nutrients from high latitudes to the tropics. Thanks to an increasing number of observations from autonomous instruments and Argo floats, our understanding of the sources...

In addition to nutrients and light, temperature plays a crucial role in marine biogeochemical processes. In this study, the sensitivity of the growth rate of phytoplankton to temperature was systematically studied by using a two-level nested physical–biogeochemical coupled model for the Yangtze River estuary of the East China Sea. The physical comp...

Phytoplankton, the dominant marine primary producers, are considered highly sensitive indicators of ecosystem conditions and changes. The East China Sea (ECS) includes a variety of oceanic and coastal domains that collectively challenge our understanding of phytoplankton dynamics and controls. This study evaluates the seasonal and interannual varia...

Submesoscale processes in the ocean vary rapidly in both space and time, and are often difficult to capture by field observations. Their dynamical connection with marine biology remains largely unknown because of the intrinsic link between temporal and spatial variations. In May 2015, satellite chlorophyll data demonstrated high concentration patch...

Based on the optical properties of water constituents, the vertical variation of photosynthetically available radiation (PAR) can be well modeled with hyperspectral resolution; the intensive computing load, however, demands simplified modeling that can be easily embedded in marine physical and biogeochemical models. While the vertical PAR profile i...

Typhoons pose great threats to coastal regions, leaving distinctive ocean surface changes along the typhoon track before landing. However, a quantitative description of the spatial and temporal patterns of typhoon-induced oceanic responses remains unclear. Sixteen years of composited data of sea surface temperature (SST) and sea surface chlorophyll...

Long-term multi-satellite-based DINEOF-reconstructed chlorophyll-a data are utilized to generate an updated biogeography of phytoplankton seasonality and to decipher the environmental controls in the Arabian Sea (AS). As in published information, the biogeographical clusters and biological boundary of phytoplankton seasonality are mostly organized...

Chub mackerel is one of the most important fisheries target species worldwide. These fish have large fluctuations in biomass, the mechanism of which remains unclear. This study developed a bioenergetics individual-based model for chub mackerel distributed in the Northwest Pacific and evaluated the dominant environmental factors that affect their ea...

Contrasting decrease and increase trends of sea surface temperature (SST) have been documented in the western Subarctic (WSA) and the rest of the Northwest Pacific (NWP) from 1958 to 2017, respectively. Consequently, more (less) total carbon dioxide (TCO2) due to ocean cooling (warming) is transported to the surface, which leads to increase (decrea...

Marine biogeochemical models have been widely used to understand ecosystem dynamics and biogeochemical cycles. To resolve more processes, models typically increase in complexity, and require optimization of more parameters. Data assimilation is an essential tool for parameter optimization, which can reduce model uncertainty and improve model predic...

In the South Indian Ocean (SIO), high surface chlorophyll concentrations are often observed in mesoscale anticyclonic eddy cores. Yet the role of submesoscale dynamics in modulating phytoplankton distributions remains largely unknown in the region. By using a biogeochemical‐Argo float and a high‐resolution model, we show that elevated chlorophyll c...

The subarctic northeast Pacific Ocean (SNEP) is a high-nitrate, low-chlorophyll region where, due to iron (Fe) limitation, chlorophyll a (chl a) concentration is persistently low throughout the year despite abundant nitrate. Observations from a Biogeochemical-Argo float (BGC-Argo) deployed in the SNEP in 2012 show prominent variations in chl a in t...

The South China Sea (SCS) is the largest semi-enclosed marginal sea in the western Pacific. The alternation of East Asian monsoon causes a significant seasonal pattern of chlorophyll, primary productivity, and export flux of sinking particles. However, the source and sink of dissolved organic carbon (DOC) pools with different bioavailability are le...

The subarctic Pacific is one of the major high-nitrate, low-chlorophyll (HNLC) regions where marine productivity is greatly limited by the supply of iron (Fe) in the region. There is a distinct seasonal difference in the chlorophyll concentrations of the east and west sides of the subarctic Pacific because of the differences in their driving mechan...

The Pearl River delivers a large amount of freshwater, sediments and nutrients to the northern shelf of the South China Sea (SCS). In June 2015, an anomalously strong phytoplankton bloom was captured by satellite images in the slope region of the northern SCS, which was associated with the southeastward spreading of the river plume on the shelf and...

Mesoscale eddies may enhance nutrient injection into the photic zone and ultimately the magnitude and composition of particle export to depth. Using satellite altimetry, we identified 38 cyclonic eddies that passed in close proximity to the Hawaii Ocean Time‐series (HOT) Station ALOHA, located in the North Pacific Subtropical Gyre, from 1993 to 201...

Our understanding of eutrophication‐induced acidification in estuaries and coastal oceans is complicated by the seasonally and spatially changing interactions between physical and biochemical drivers. By combining the conservative mixing method and a physical‐biogeochemical model, we present the seasonal and spatial dynamical analysis of eutrophica...

The mooring tethered time-series sediment traps (TS-traps) collect sinking particles in the ocean, enabling the estimation of biological pump (BP) efficiency based on the assumption of vertical settling. However, the advection of sea water can disperse particles over long distance during the sinking process, introducing uncertainties into the estim...

The phytoplankton and zooplankton biomass as well as nutrients in the southern region of Kuroshio Extension (KE) presents obvious decadal variability. Both local and remote links between biomass and physical properties are investigated by comparing satellite observations and the outputs from a biological-physical coupled model. The Regional Ocean M...

The northern South China Sea (NSCS) is a dynamically complex region whose shelf and slope currents are driven by different mechanisms. In this study, we used field measurements to identify clear interannual variations in the circulation related to the El Niño-Southern Oscillation cycle. To investigate the modulation mechanisms, we used a high-resol...

Given their ephemeral nature, eddies have proven difficult to study, with contrary results from field observations that typically sample at the center during a specific stage of an eddy lifespan. Using the natural occurring radionuclide ²³⁴Th, we examined particle fluxes within two cyclonic eddies (CEs) at different evolutionary stages (mature stag...

This study examines temporal variations of ²³⁴Th-based particle export based on time-series observations conducted from 2004 to 2014 at the South-East Asian Time-series Study (SEATS) site in the basin area of the Northern South China Sea. It shows significant variability in particle export at both seasonal and interannual time scales. A significant...

The penetration of visible solar radiation (VSR) in the upper ocean contributes to heating in the upper water column, and this process is modulated by constituents in water such as phytoplankton. Various schemes have been developed to propagate surface VSR to deeper depths, which are incorporated in ocean circulation models to study basin‐scale imp...

A three‐dimensional physical‐biological model was used to study the dynamics of physical and biological processes in the central California Current System (CCS) from 1993 to 2016 and investigate its response to different climate modes. The variations of new production (NP) and nitrate fluxes in the central CCS showed robust seasonal and interannual...

Plain Language Summary Subtropical gyres are characterized as being nutrient‐depleted at the surface, and mesoscale and submesoscale processes are the key physical activities facilitating the transport of nutrients into the upper ocean. Submesoscale dynamics lead to more intense vertical motion and the enhanced upward transport of nutrients, thereb...

The chlorophyll in the northern South China Sea (NSCS) shows strong interannual variability between different phases of the El Niño‐Southern Oscillation (ENSO), primarily due to the influence from Kuroshio intrusion. Chlorophyll observations also reveal that significant year‐to‐year variation remains in the same ENSO phase, but its controlling mech...

The South China Sea (SCS) is strongly influenced by the East Asian monsoon system with seasonal reversal. Measurements from a 7-year continuous sediment trap located in the central SCS showed a clear seasonal pattern. The particulate organic carbon (POC) export flux at the depth of 1200 m was considerably higher in monsoon seasons. The driving dyna...

Observations from two Bio‐Argo floats deployed in the northern and central South China Sea (SCS) show distinct seasonal patterns of vertical chlorophyll distribution. There is a permanent subsurface chlorophyll maximum (SCM) located between 60 and 80 m throughout the year and a weak seasonality of surface chlorophyll in the central SCS. In the nort...

Coastal upwelling ecosystems are among the most productive ecosystems in the world, meaning that their response to climate change is of critical importance. Our understanding of climate change impacts on marine ecosystems is largely limited to the open ocean, mainly because coastal upwelling is poorly reproduced by current earth system models. Here...

New evidences were provided that Kuroshio intrusion in winter is able to increase phytoplankton growth in the open ocean of the northern South China Sea (SCS) based on multiple data sources. Strong fronts due to Kuroshio intrusion and interactions with the SCS water are associated with intense upwelling, supplying high nutrients from the subsurface...

The cause for large variability of hypoxia off the Changjiang Estuary has not been well understood partly due to various nutrient sources and complex physical-biological processes involved. The Regional Ocean Modeling Systems (ROMS) coupled with Carbon, Silicate and Nitrogen Ecosystem (CoSiNE) was used to investigate the 2006 hypoxia in the East Ch...

Temporal evolution of near-surface chlorophyll (CHL) associated with mesoscale eddies over entire eddy lifespan is complicated. Based on satellite measurements and a reanalysis dataset, we identify and quantify major temporal and spatial CHL responses in cyclonic eddies in the southeastern Pacific, and explore the associated mechanisms. Only few te...

This study shows that the response of satellite-observed chlorophyll (CHL) to eddy motion varies seasonally in the South China Sea (SCS). The spatial pattern of the CHL anomaly composite for eddies is a dipole in summer and a monopole in winter, indicating that sea surface CHL is largely regulated by the horizontal rotational velocity of the eddy i...

The third Chinese National Arctic Research Expedition (CHINARE) was conducted in the summer of 2008. During the survey, the surface seawater partial pressure of CO2 (pCO2) was measured, and sea water samples were collected for CO2 measurement in the Canada Basin. The distribution of pCO2 in the Canada Basin was determined, the influencing factors w...

The zonal velocity produced by a Regional Ocean Modeling System (ROMS)-based Pacific Ocean circulation model was validated against in situ measurements along the 137°E longitude. The Pacific model successfully reproduced the position and the shape of the North Equatorial Current (NEC) as well as the latitude of maximum surface velocity in the NEC r...

Observations suggest that subsurface waters in the northern South China Sea (NSCS) exhibited substantial low-frequency variability, with a striking decadal change in the southern limit of the 34.6-psu isohaline. Long-term freshening of the subsurface waters started in 1960, was followed by salinification from 1975, and freshening occurred again fro...

Mesoscale eddies can influence biogeochemical cycles through both vertical nutrient or plankton flux and horizontal advection of nutrient or plankton in eddy periphery. In this study, we analyzed the seasonal and spatial variability of near-sea-surface chlorophyll-a concentrations and their corresponding modulation mechanisms by collocating satelli...

Using high-resolution in situ data from gliders, satellite data of sea level anomaly and geostrophic currents, we presented the detailed structure of an anticyclonic eddy during spring 2015 in the northern South China Sea. The impact depth of the anticyclonic eddy reached about 1000 m and had a maximum temperature anomaly of about 3°C at ?120 m and...

A coupled physical-biochemical Indian Ocean Regional Model (IORM), based on the Navy Coastal Ocean Model (NCOM) and the Carbon Silicate Nitrogen Ecosystem (CoSiNE) model was configured with the primary objective of providing an accurate estimate of the oceanic physical state along with the biochemical processes simulated by CoSiNE to understand the...

Biogeochemical cycles associated with mesoscale eddies in the South China Sea (SCS) were investigated. The study was based on a coupled physical–biogeochemical Pacific Ocean model (Regional Ocean Model System–Carbon, Silicate, and Nitrogen Ecosystem, ROMS-CoSiNE) simulation for the period from 1991 to 2008. A total of 568 mesoscale eddies with life...