A Large Winter Chlorophyll‐a Bloom in the Southeastern Bay of Bengal Associated With the Extreme Indian Ocean Dipole Event in 2019

Li, Zhiyuan; Yu, Long; Huang, Saihua; Xie, Huawei; Zhou, Yu; Yang, Bin; Bai, Yu; Zhu, Xiao‐Hua

doi:10.1029/2022jc018791

Cited by 4 publications

(1 citation statement)

References 59 publications

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“…The Rossby waves could pass through the Andaman Sea to the BoB via these channels and influence the circulation in the BoB [28]. According to previous studies, the Rossby waves, reflected by coastal Kelvin waves at the eastern boundary of the BoB, manifest as eddy-like SLAs and propagate westward [29][30][31]. Thus, in our study, the westward propagation signals of low salinity at 15 • N and the salinity anomaly at 10 • N were likely attributed to the westward movement of eddy-like currents associated with Rossby waves.…”

Section: Discussionmentioning

confidence: 96%

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Chen,

Qiu,

Jing

et al. 2024

Remote Sensing

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In this study, we investigate the connection between planetary equatorial waves, modulated by the Indian Ocean dipole (IOD) and El Niño Southern Oscillation (ENSO), and the interannual variabilities of the salinity distribution in the Bay of Bengal (BoB) in October–December (OND), along with its associated dynamics, using satellite and reanalysis datasets. In OND 2010 and 2016 (1994, 1997, 2006, and 2019), positive (negative) sea surface salinity anomalies (SSSAs) were distributed in the eastern equatorial Indian Ocean (EIO) and Andaman Sea. Moreover, the southward movement of negative (positive) SSSAs along the eastern Indian coast was observed. This phenomenon was caused by large-scale anomalous currents associated with zonal wind over the EIO. During OND 2010 and 2016 (1994, 1997, 2006, and 2019), due to anomalous westerlies (easterlies) over the EIO and anomalous downwelling (upwelling) Kelvin waves, the strengthened (weakened) Wyrtki jet and the basin-scale anomalous cyclonic (anticyclonic) circulation in the BoB gave rise to positive (negative) SSSAs within the eastern EIO and Andaman Sea. In addition, the intensified (weakened) eastern Indian coastal currents led to the southward movement of negative (positive) SSSAs. It is worth noting that downwelling Kelvin waves reached the western coast of India during OND 2010 and 2016, while upwelling Kelvin waves were only confined to the eastern coast of India during OND 1994, 1997, 2006, and 2019. Furthermore, westward salinity signals associated with reflected westward Rossby waves could modulate the spatial pattern of salinity. The distribution of salinity anomalies could potentially influence the formation of the barrier layer, thereby impacting the sea surface temperature variability and local convection.

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Section: Discussionmentioning

confidence: 96%

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Chen,

Qiu,

Jing

et al. 2024

Remote Sensing

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Modulation of Surface Seawater CO₂ System at 80°E: Impacts of the Positive IOD in 2019

Murata,

Kouketsu,

Sasaoka

et al. 2024

JGR Oceans

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To elucidate impacts of an Indian Ocean Dipole (IOD) event on surface seawater CO2 dynamics, we analyzed data collected along the World Ocean Circulation Experiment Hydrographic Program I08 N line (latitudes 20°S–6°N at 80°E) in December 2019, when a strong positive IOD (pIOD) event occurred. After removing the effects of anthropogenic CO2 accumulation, we examined anomalies of the surface seawater CO2 fugacity (fCO2) from the climatology in relation to other marine properties. At latitudes 11°S–6°S, where horizontal advection of upwelled water off Sumatra was observed, dissolved inorganic carbon and total alkalinity, both normalized to a salinity of 35 (nTCO2 and nTA) showed positive anomalies of +11.4 and +8.1 μmol kg−1, respectively. At latitudes 5°S–5°N, where distinct low‐salinity water was observed because of the pIOD, nTCO2 and nTA showed negative anomalies of −4.0 and ‒0.5 μmol kg−1, respectively. The combined effects of the nTCO2 and nTA anomalies on fCO2 made the observed fCO2 anomalies small, +3.2 and −6.6 μatm for 6°S–11°S and 5°S–5°N, respectively, because the direction of the Revelle factor for TCO2 is opposite to that for TA. We estimated that the pIOD modulated the air–sea CO2 flux by +0.45 and −0.55 mmol m−2 d−1 on average within11°S–6°S and 5°S–5°N, respectively. The impacts of the pIOD on the CO2 dynamics could be explained by the anomalous salinity conditions associated with upwelled water and the freshwater balance.

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Summer marine heatwaves in the tropical Indian Ocean associated with an unseasonable positive Indian Ocean Dipole event 2012

Li,

Wu,

et al. 2024

Front. Mar. Sci.

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Marine heatwaves (MHWs) are anomalously warm events that profoundly affect climate change and local ecosystem. During the summer of 2012 (June–September), intense MHWs occurred in the tropical Indian Ocean (TIO) concurrently with an unseasonable positive Indian Ocean Dipole (pIOD) event. The MHW metrics (duration, frequency, cumulative intensity and maximum intensity) were characterized by northwestward–slanted patterns from west Australia to the Somalia coast. The analysis confirmed that these MHWs were closely associated with the unseasonable pIOD 2012. The weakening of Western North Pacific Subtropical High and strengthening of Australian High in spring induced an interhemispheric pressure gradient that drove two anticyclonic circulation patterns over the eastern TIO. The first anticyclonic circulation featured cross–equatorial wind anomalies from south of Java to the South China Sea/Philippine Sea, which led to strong upwelling off Sumatra–Java during the subsequent summer. The second anticyclonic circulation excited downwelling Rossby waves that propagated from the southeastern TIO to the western TIO. Thus, downwelling in the western pole and upwelling in the eastern pole led to a strong pIOD event peaking in summer, namely, the unseasonable pIOD 2012. These downwelling Rossby waves deepened the thermocline by more than 60 m and caused anomalous surface warming, thereby contributing to the occurrences of MHWs. With the development and peak of the unseasonable pIOD 2012, anomalous atmospheric circulation transported moisture from the TIO to the subtropical Western North Pacific (WNP), favoring a strong cyclonic anomaly that profoundly affected the summer monsoon rainfall over the subtropical WNP. This study provides some perspectives on the role of pIOD events in summer climate over the Indo–Northwest Pacific region.

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A Large Winter Chlorophyll‐a Bloom in the Southeastern Bay of Bengal Associated With the Extreme Indian Ocean Dipole Event in 2019

Cited by 4 publications

References 59 publications

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Modulation of Surface Seawater CO₂ System at 80°E: Impacts of the Positive IOD in 2019

Summer marine heatwaves in the tropical Indian Ocean associated with an unseasonable positive Indian Ocean Dipole event 2012

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A Large Winter Chlorophyll‐a Bloom in the Southeastern Bay of Bengal Associated With the Extreme Indian Ocean Dipole Event in 2019

Cited by 4 publications

References 59 publications

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Unraveling the Influence of Equatorial Waves on Post-Monsoon Sea Surface Salinity Anomalies in the Bay of Bengal

Modulation of Surface Seawater CO2 System at 80°E: Impacts of the Positive IOD in 2019

Summer marine heatwaves in the tropical Indian Ocean associated with an unseasonable positive Indian Ocean Dipole event 2012

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Modulation of Surface Seawater CO₂ System at 80°E: Impacts of the Positive IOD in 2019