Temporal Variation of Summer Hypoxia off Changjiang Estuary During 1997–2014 and Its Association With ENSO

Frontiers in Marine Science

Anqi Liu¹  Daji Huang²  Bin Wang³  Qiang Zhao⁴  Jia Li⁵  Dingyong Zeng⁵  Di Tian⁵  Qicheng Meng⁵  Xiao Ma⁵  Feng Zhou⁶ 

[1] College of Oceanography, Hohai University, Nanjing, China;Fourth Institute of Oceanography, Ministry of Natural Resources, Beihai, China;Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China;Ningbo Marine Environment Monitoring Center Station, Ministry of Natural Resources, Ningbo, China;Observation and Research Station of Yangtze River Delta Marine Ecosystems, Ministry of Natural Resources, Zhoushan, China;School of Oceanography, Shanghai Jiao Tong University, Shanghai, China;State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China;

关键词: Hypoxia;    Changjiang Estuary;    East China Sea;    repeated hydrographic section;    ENSO;   

DOI  :  10.3389/fmars.2022.897063

来源: DOAJ

【 摘 要 】

Temporal variation of summer hypoxia, along a repeated hydrographic section from the Changjiang River mouth to Cheju Island, is investigated using cruise data during 1997–2014. The climatological mean of dissolved oxygen (DO) presents a “dual-core structure” below the oxycline, associated with two hypoxic centers near the river mouth and offshore of the Changjiang Bank, respectively. The DO value is highly variable from year to year, with dramatic interannual variation but an insignificant linear trend during 1997–2014. Composite analysis indicates that the interannual variation of DO and associated hypoxia events are strongly affected by the El Niño–Southern Oscillation (ENSO) cycle. In the El Niño decaying summer, large river discharge and relatively strong stratification, combined with calm climatic and hydrographic conditions, enhance DO depletion off the Changjiang Estuary. It is likely that El Niño is not a prerequisite for hypoxia occurrences. However, El Niño did enhance bottom hypoxia probability off the Changjiang Estuary during 1997–2014.

【 授权许可】

Unknown