Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sustenance of phytoplankton in the subpolar North Atlantic during the
  winter through patchiness   This study investigates the influence of two factors that change the mixed
layer depth and can potentially contribute to the phytoplankton sustenance over
winter: 1) variability of air-sea fluxes and 2) three-dimensional processes
arising from strong fronts. To study the role of these factors, we perform
several three-dimensional numerical simulations forced with air-sea fluxes at
different temporal averaging frequencies as well as different spatial
resolutions. Results show that in the winter, when the average mixed layer is
much deeper than the euphotic layer and the days are short, phytoplankton
production is relatively insensitive to the high-frequency variability in
air-sea fluxes. The duration of upper ocean stratification due to
high-frequency variability in air-sea fluxes is short and hence has a small
impact on phytoplankton production. On the other hand, slumping of fronts
creates patchy, stratified, shallow regions that persist considerably longer
than stratification caused by changes in air-sea fluxes. Simulations show that
before spring warming, the average MLD with fronts is about 700 m shallower
than the average MLD without fronts. Therefore, fronts increase the residence
time of phytoplankton in the euphotic layer and contribute to phytoplankton
growth. Results show that before the spring warming, the depth-integrated
phytoplankton concentration is about twice as large as phytoplankton
concentration when there are no fronts. Hence, fronts are important for setting
the MLD and sustaining phytoplankton in the winter. Model results also show
that higher numerical resolution leads to stronger restratification, shallower
mixed layers, greater variability in the MLD and higher production of
phytoplankton.

16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th