@article{fdi:010071992,
  title = {{I}ntensification and deepening of the {A}rabian {S}ea oxygen minimum zone in response to increase in {I}ndian monsoon wind intensity},
  author = {{L}achkar, {Z}. and {L}evy, {M}arina and {S}mith, {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he decline in oxygen supply to the ocean associated with global warming is expected to expand oxygen minimum zones ({OMZ}s). {T}his global trend can be attenuated or amplified by regional processes. {I}n the {A}rabian {S}ea, the world's thickest {OMZ} is highly vulnerable to changes in the {I}ndian monsoon wind. {E}vidence from paleorecords and future climate projections indicates strong variations of the {I}ndian monsoon wind intensity over climatic timescales. {Y}et, the response of the {OMZ} to these wind changes remains poorly understood and its amplitude and timescale unexplored. {H}ere, we investigate the impacts of perturbations in {I}ndian monsoon wind intensity (from 50 to +50 %) on the size and intensity of the {A}rabian {S}ea {OMZ}, and examine the biogeochemical and ecological implications of these changes. {T}o this end, we conducted a series of eddy-resolving simulations of the {A}rabian {S}ea using the {R}egional {O}cean {M}odeling {S}ystem ({ROMS}) coupled to a nitrogen-based nutrient-phytoplankton-zooplankton-detritus ({NPZD}) ecosystem model that includes a representation of the {O}-2 cycle. {W}e show that the {A}rabian {S}ea productivity increases and its {OMZ} expands and deepens in response to monsoon wind intensification. {T}hese responses are dominated by the perturbation of the summer monsoon wind, whereas the changes in the winter monsoon wind play a secondary role. {W}hile the productivity responds quickly and nearly linearly to wind increase (i.e., on a timescale of years), the {OMZ} response is much slower (i.e., a timescale of decades). {O}ur analysis reveals that the {OMZ} expansion at depth is driven by increased oxygen biological consumption, whereas its surface weakening is induced by increased ventilation. {T}he enhanced ventilation favors episodic intrusions of oxic waters in the lower epipelagic zone (100-200 m) of the western and central {A}rabian {S}ea, leading to intermittent expansions of marine habitats and a more frequent alternation of hypoxic and oxic conditions there. {T}he increased productivity and deepening of the {OMZ} also lead to a strong intensification of denitrification at depth, resulting in a substantial amplification of fixed nitrogen depletion in the {A}rabian {S}ea. {W}e conclude that changes in the {I}ndian monsoon can affect, on longer timescales, the large-scale biogeochemical cycles of nitrogen and carbon, with a positive feedback on climate change in the case of stronger winds. {A}dditional potential changes in large-scale ocean ventilation and stratification may affect the sensitivity of the {A}rabian {S}ea {OMZ} to monsoon intensification.},
  keywords = {{ARABIE} {MER}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {15},
  numero = {1},
  pages = {159--186},
  ISSN = {1726-4170},
  year = {2018},
  DOI = {10.5194/bg-15-159-2018},
  URL = {https://www.documentation.ird.fr/hor/fdi:010071992},
}