Modulation of the Intraseasonal Chlorophyll‐a Concentration in the Tropical Indian Ocean by the Central Indian Ocean Mode

Qin, Jianhuang; Meng, Ze; Xu, Wei; Li, Baosheng; Cheng, Xuhua; Murtugudde, Raghu

doi:10.1029/2022gl097802

Cited by 7 publications

(3 citation statements)

References 49 publications

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“…Physical–biogeochemical models are useful tools for the analysis of the variability of subsurface Chl under the influence of physical processes such as upwelling, eddies, fronts and sub‐mesoscale currents (Gan et al., 2010; Guo et al., 2017; Lévy et al., 2018; Xiu & Chai, 2011). The fully coupled physical–ecosystem model developed by the Darwin project of the Massachusetts Institute of Technology (https://darwinproject.mit.edu) has been successful in modeling the key phytoplankton size classes and seasonal/intra‐seasonal variation of surface Chl (Qin et al., 2022) and has already been used by several research groups to study phytoplankton community structure (Benoiston et al., 2017; Kuhn et al., 2019; Mangolte et al., 2022). This well‐tested and eddy‐permitting model is useful for studying the impact of mesoscale eddies on SCM characteristics and phytoplankton community.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale Eddy Modulation of Subsurface Chlorophyll Maximum Layers in the South China Sea

Xu,

Wang,

Cheng

et al. 2023

JGR Biogeosciences

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Subsurface chlorophyll maximum (SCM) layers contribute considerably to the integrated biomass of the water column and can be strongly modulated by mesoscale eddies that are ubiquitous in the global ocean. The mechanisms of eddy‐induced surface chlorophyll concentration have been extensively examined in the South China Sea (SCS). However, the potential impact of mesoscale eddies on SCM layers remains unclear. We examined the influence of mesoscale eddies on the depth, thickness and magnitude of SCM layers in the SCS using output from an eddy‐permitting biological–physical coupled model over a 22‐year period. Our study shows that nutrient distribution is largely driven by eddy dynamics, with cyclonic eddies enhancing the supply of inorganic nutrients in the upper layers by uplifting the thermocline, and downward displacement of the thermocline in anticyclonic eddies, reducing the nutrient supply into the euphotic zone from the depth. We found that anticyclonic (cyclonic) eddies are responsible for increased (decreased) SCM depth and decreased (increased) SCM magnitude; SCM thickness decreased in cyclonic eddies but slightly increased in anticyclonic eddies. The effects of mesoscale eddies depend on eddy amplitude. Maximal anomalies in depth, thickness and magnitude always occur near the center of eddies. Phytoplankton community structure at SCM layers is also affected by eddies, with more diatoms in cyclonic eddies and more coccolithophores in anticyclonic eddies. Our study will advance our understanding of mesoscale physical–biogeochemical interactions.

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Section: Introductionmentioning

confidence: 99%

Mesoscale Eddy Modulation of Subsurface Chlorophyll Maximum Layers in the South China Sea

Xu,

Wang,

Cheng

et al. 2023

JGR Biogeosciences

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“…Determining MISO trends is thus critically important for understanding future changes in the spatial pattern of ISM. Meanwhile, it was widely reported that MISO has a large influence on extreme weather and climate events (Kikuchi & Wang, 2010; Li et al., 2013, 2020; Qin et al., 2022; Singh et al., 2014; Vinnarasi & Dhanya, 2016). Our results aid the understanding of potential contributions to extreme events from the perspective of intraseasonal variability during ISM.…”

Section: Introductionmentioning

confidence: 99%

Increase in Intraseasonal Rainfall Driven by the Arabian Sea Warming in Recent Decades

Zhou

Qin

et al. 2022

Geophysical Research Letters

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Intraseasonal oscillation (ISO) is the dominant variability during the Indian summer monsoon (ISM). In this study, it is found that ISOs accompanying intraseasonal rainfall are substantially enhanced over the northeastern Arabian Sea (AS) in the past three decades. The rise in rainfall agrees with the variation in moisture loading. The strengthening of the wind convergence in the planetary boundary layer (PBL) triggers the changes in vertical velocity, intensifying the advection of background moisture by the intraseasonal vertical velocity, which contributes the most to intensified moisture supply over the northeastern AS. In addition, the faster warming of the AS and the increasing cyclonic vorticity associated with the poleward movement of the summer mean low‐level jet are responsible for the increasing trend in PBL convergence. This recent intensified intraseasonal rainfall over the AS has contributed to the trend in the mean and extremes over the central‐western parts of the Indian subcontinent.

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“…Compared with the traditional water quality monitoring method based on field investigation, remote sensing technology has the advantages of a low cost, wide range and high efficiency. With the development of highresolution and multi-source satellite sensors, the retrieval of water-environment-related elements using remote sensing has been widely applied in the monitoring of water quality and hydro-environmental pollution in large areas of water [8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Using a Remote-Sensing-Based Piecewise Retrieval Algorithm to Map Chlorophyll-a Concentration in a Highland River System

Sun

Liu

et al. 2022

Remote Sensing

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Chlorophyll-a(chl-a) has been used as an important indicator of water quality. Great efforts have been invested to develop remote-sensing-based chl-a retrieval models. However, due to the spatial difference in chl-a concentration, a single model usually cannot accurately predict the whole range of chl-a concentration. To test the performance of precedent chl-a models, we carried out an experiment along the upper and middle reaches of the Kaidu River and around some small ponds in the Bayanbulak Wetland. We measured water surface reflectance in the field and analyzed the chl-a concentration in the laboratory. Initially, we performed a sensitivity analysis of the spectrum band to chl-a concentration with the aim of identifying the most suitable bands for various chl-a models. We found that the water samples could be divided into two groups with a threshold of 4.50 mg/m3. Then, we tested the performance of 11 precedent chl-a retrieval models and 7 spectral index-based regression models from this study for all the sample datasets and the two separate datasets with relatively high and low chl-a concentrations. Through a complete comparison of the performance of these models, we selected the D3B model for water bodies with high chl-a concentration and OC2 model (ocean color 2) for low chl-a concentration waters, resulting in the hierarchical and piecewise retrieval algorithm OC2-D3B. The chl-a concentration of 4.50 mg/m3 corresponded to the D3B value of −0.051; therefore, we used −0.051 as the threshold value of the OC2-D3B model. The result of the OC2-D3B model showed a better performance than the other algorithms. Finally, we mapped the spatial distribution and seasonal pattern of chl-a concentration in Bayanbulak Wetland using Sentinel-2 images from 2016 to 2019. The results indicated that the chl-a concentration in the riparian ponds was generally in the range of 8–10 mg/m3, which was higher than that in rivers with a range of 2–4 mg/m3. The highest chl-a concentration usually appears in summer, followed by spring and autumn, and the lowest in winter. The correlation between meteorological data and chl-a concentration showed that temperature is the dominant factor for chl-a concentration changes. Our analytical framework could provide a better way to accurately map the spatial distribution of chl-a concentration in complex river systems.

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Modulation of the Intraseasonal Chlorophyll‐a Concentration in the Tropical Indian Ocean by the Central Indian Ocean Mode

Cited by 7 publications

References 49 publications

Mesoscale Eddy Modulation of Subsurface Chlorophyll Maximum Layers in the South China Sea

Mesoscale Eddy Modulation of Subsurface Chlorophyll Maximum Layers in the South China Sea

Increase in Intraseasonal Rainfall Driven by the Arabian Sea Warming in Recent Decades

Using a Remote-Sensing-Based Piecewise Retrieval Algorithm to Map Chlorophyll-a Concentration in a Highland River System

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