Figure 1
Figure 1. Bering Strait
maps and biogeochemical time-series.
Bering/Chukchi seas (a) and Bering Strait (b) with
IBCAO topography (Jakobsson et al., 2000);
US-Russian border (green dashed line (b));
moorings (A1-4 (b) and Nishino et al. (2016)'s SCH
(Section 4.2) (a)); and schematic flows (b),
color-coded as per time-series (c-g, j-l), viz.
A3=black, A2=grey, A4=pink.
ACC/SCC=Alaskan/Siberian Coastal Currents. (c-i)
September 2022 to July 2023 1-day smoothed
time-series of fluorescence (c); dissolved oxygen
(showing also surface saturation) (d); nitrate
(e); temperature (f); salinity (g); and
along-channel (h) and across-channel (i) velocity
at various depths (color-code in title), marking
also sea-ice presence (f), season (d), and winter
nitrate/across-channel flow correspondence, arrows
(e,i) (Section 4,1). Stars (d, h) indicate step
increases in oxygen and related flow events
(Section 3.2). Hourly fall (17th October - 26th
November 2022) time-series of nitrate (j),
salinity (k), temperature (l), and along-channel
velocity at various depths (m).
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Figure 2
Figure 2. Hourly
temperature, salinity and nitrate at A3.
Time-series of temperature (a), salinity (b), and
nitrate (c), each color-coded by time-periods of
Figure 1d (fall=red, pink; winter=cyan, blue;
spring=green, black) and corresponding
temperature-salinity (d) and nitrate-salinity (e)
plots, separated (i,ii,iii) by season (dates
indicated) and color-coded by time-period as for
time-series (with grey indicating the entire
record). Nitrate-salinity plots (e) mark also
nitrate-salinity fits of Hennon et al. (2022) for
all seasons (dashed) and the season represented
(solid).
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Figure 3
Figure 3. Seasonal and
interannual Bering Strait nitrate flux estimates.
For September 2022-July 2023, (grey/black) monthly
mean (with standard errors) A3 volume transport
(a.i), lower layer A3 nitrate (a.ii), and nitrate
flux assuming a 10 or 20m depleted layer for June
to November (a.iii). Blue/cyan shows Hennon et al.
(2022), 1997-2018 average nitrate (a.ii) and
nitrate flux (a.iii). (b) Idealized seasonal cycle
of nitrate for the interannual calculation
(Section 5.3) showing depth of depleted layer
(b.i), time variability of lower layer nitrate
(b.ii), and product of these two fields (b.iii),
i.e. the weighting for transport for flux
calculations. (c) 12-month (black/green) and
6-month (gray) smoothed volume flux (c.i) and
nitrate flux assuming no interannual variability
in nitrate concentrations) (c.ii), with trend
lines (black) and values (m, top left, with 95%
error).
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