@article{fdi:010083300,
  title = {{F}ast local warming is the main driver of recent deoxygenation in the northern {A}rabian {S}ea},
  author = {{L}achkar, {Z}. and {M}ehari, {M}. and {A}l {A}zhar, {M}. and {L}evy, {M}arina and {S}mith, {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {A}rabian {S}ea ({AS}) hosts one of the most intense oxygen minimum zones ({OMZ}s) in the world. {O}bservations suggest a decline in {O}-2 in the northern {AS} over the recent decades accompanied by an intensification of the suboxic conditions there. {O}ver the same period, the local sea surface temperature has risen significantly, particularly over the {A}rabian {G}ulf (also known as {P}ersian {G}ulf, hereafter the {G}ulf), while summer monsoon winds may have intensified. {H}ere, we simulate the evolution of dissolved oxygen in the {AS} from 1982 through 2010 and explore its controlling factors, with a focus on changing atmospheric conditions. {T}o this end, we use a set of eddy-resolving hindcast simulations forced with winds and heat and freshwater fluxes from an atmospheric reanalysis. {W}e find a significant deoxygenation in the northern {AS}, with {O}-2 inventories north of 20 degrees {N} dropping by over 6 % per decade between 100 and 1000 m. {T}hese changes cause an expansion of the {OMZ} volume north of 20 degrees {N} at a rate of 0.6 % per decade as well as an increase in the volume of suboxia and the rate of denitrification by 14 and 15 % per decade, respectively. {W}e also show that strong interannual and decadal variability modulate dissolved oxygen in the northern {AS}, with most of the {O}-2 decline taking place in the 1980s and 1990s. {U}sing a set of sensitivity simulations we demonstrate that deoxygenation in the northern {AS} is essentially caused by reduced ventilation induced by the recent fast warming of the sea surface, including in the {G}ulf, with a contribution from concomitant summer monsoon wind intensification. {T}his is because, on the one hand, surface warming enhances vertical stratification and increases {G}ulf water buoyancy, thus inhibiting ver- tical mixing and ventilation of the thermocline. {O}n the other hand, summer monsoon wind intensification causes a rise in the thermocline depth in the northern {AS} that lowers {O}-2 levels in the upper ocean. {O}ur findings confirm that the {AS} {OMZ} is strongly sensitive to upper-ocean warming and concurrent changes in the {I}ndian monsoon winds. {F}inally, our results also demonstrate that changes in the local climatic forcing play a key role in regional dissolved oxygen changes and hence need to be properly represented in global models to reduce uncertainties in future projections of deoxygenation.},
  keywords = {{ARABIE} {MER}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {18},
  numero = {20},
  pages = {5831--5849},
  ISSN = {1726-4170},
  year = {2021},
  DOI = {10.5194/bg-18-5831-2021},
  URL = {https://www.documentation.ird.fr/hor/fdi:010083300},
}