@article{fdi:010082213,
  title = {{T}he fate of upwelled nitrate off {P}eru shaped by submesoscale filaments and fronts},
  author = {{H}auschildt, {J}. and {T}homsen, {S}. and {E}chevin, {V}incent and {O}schlies, {A}. and {J}ose, {Y}. {S}. and {K}rahmann, {G}. and {B}ristow, {L}. {A}. and {L}avik, {G}.},
  editor = {},
  language = {{ENG}},
  abstract = {{F}ilaments and fronts play a crucial role for a net offshore and downward nutrient transport in {E}astern {B}oundary {U}pwelling {S}ystems ({EBUS}s) and thereby reduce regional primary production. {M}ost studies on this topic are based on either observations or model simulations, but only seldom are both approaches are combined quantitatively to assess the importance of filaments for primary production and nutrient transport. {H}ere we combine targeted interdisciplinary shipboard observations of a cold filament off {P}eru with submesoscale-permitting (1/45 degrees) coupled physical ({C}oastal and {R}egional {O}cean {C}ommunity model, {CROCO}) and biogeochemical ({P}elagic {I}nteraction {S}cheme for {C}arbon and {E}cosystem {S}tudies, {PISCES}) model simulations to (i) evaluate the model simulations in detail, including the timescales of biogeochemical modification of the newly upwelled water, and (ii) quantify the net effect of submesoscale fronts and filaments on primary production in the {P}eruvian upwelling system. {T}he observed filament contains relatively cold, fresh, and nutrient-rich waters originating in the coastal upwelling. {E}nhanced nitrate concentrations and offshore velocities of up to 0.5 m s(-1) within the filament suggest an offshore transport of nutrients. {S}urface chlorophyll in the filament is a factor of 4 lower than at the upwelling front, while surface primary production is a factor of 2 higher. {T}he simulation exhibits filaments that are similar in horizontal and vertical scale compared to the observed filament. {N}itrate concentrations and primary production within filaments in the model are comparable to observations as well, justi- fying further analysis of nitrate uptake and subduction using the model. {V}irtual {L}agrangian floats were released in the subsurface waters along the shelf and biogeochemical variables tracked along the trajectories of floats upwelled near the coast. {I}n the submesoscale-permitting (1/45 degrees) simulation, 43 % of upwelled floats and 40 % of upwelled nitrate are subducted within 20 d after upwelling, which corresponds to an increase in nitrate subduction compared to a mesoscale-resolving (1/9 degrees) simulation by 14 %. {T}aking model biases into account, we give a best estimate for subduction of upwelled nitrate off {P}eru between 30 %-40 %. {O}ur results suggest that submesoscale processes further reduce primary production by amplifying the downward and offshore export of nutrients found in previous mesoscale studies, which are thus likely to underestimate the reduction in primary production due to eddy fluxes. {M}oreover, this downward and offshore transport could also enhance the export of fresh organic matter below the euphotic zone and thereby potentially stimulate microbial activity in regions of the upper offshore oxygen minimum zone.},
  keywords = {{PEROU} ; {ZONE} {TROPICALE} ; {PACIFIQUE}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {18},
  numero = {12},
  pages = {3605--3629},
  ISSN = {1726-4170},
  year = {2021},
  DOI = {10.5194/bg-18-3605-2021},
  URL = {https://www.documentation.ird.fr/hor/fdi:010082213},
}