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Effects of Oceanic Mesoscale and Submesoscale Frontal Processes on the Vertical Transport of Phytoplankton
Author(s) -
Ruiz Simón,
Claret Mariona,
Pascual Ananda,
Olita Antonio,
Troupin Charles,
Capet Arthur,
TovarSánchez Antonio,
Allen John,
Poulain PierreMarie,
Tintoré Joaquín,
Mahadevan Amala
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015034
Subject(s) - downwelling , mesoscale meteorology , pycnocline , upwelling , phytoplankton , geology , advection , mixed layer , oceanography , frontogenesis , stratification (seeds) , environmental science , atmospheric sciences , chemistry , physics , organic chemistry , nutrient , thermodynamics , seed dormancy , germination , botany , dormancy , biology
Oceanic fronts are dynamically active regions of the global ocean that support upwelling and downwelling with significant implications for phytoplankton production and export. However (on time scales ≳ the inertial time scale), the vertical velocity is 10 3 –10 4 times weaker than the horizontal velocity and is difficult to observe directly. Using intensive field observations in conjunction with a process study ocean model, we examine vertical motion and its effect on phytoplankton fluxes at multiple spatial horizontal scales in an oligotrophic region in the Western Mediterranean Sea. The mesoscale ageostrophic vertical velocity (∼10 m/day) inferred from our observations shapes the large‐scale phytoplankton distribution but does not explain the narrow (1–10 km wide) features of high chlorophyll content extending 40–60 m downward from the deep chlorophyll maximum. Using modeling, we show that downwelling submesoscale features concentrate 80% of the downward vertical flux of phytoplankton within just 15% of the horizontal area. These submesoscale spatial structures serve as conduits between the surface mixed layer and pycnocline and can contribute to exporting carbon from the sunlit surface layers to the ocean interior.