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<p>Dear Yuxin, <br>
</p>
<p>in both of your setups I would not expect much response in the
deep oxygen. In the first, AMOC recovers probably quickly, so
there is not much reason to change. In the second, ten years is
still fairly short, for changing tracer distributions in the
deeper parts of the ocean. The timescale of ventilation of
intermediate waters is on the order of several decades, in the
deep ocean it is centuries to millenia. So I expect yo will at
least have to run 1000 years with continuously changed overtrning
to see some larger effects in the deep North Atlantic. Maybe have
a look at the distribution of CFCs or anthropogenic carbon in the
North Atlantic from the GLODAP data base; then you see
observations of how far a signal from the surface penetrates
within the deep Atlantic within a few decades. <br>
</p>
<p>Cheers, Christoph<br>
</p>
<div class="moz-cite-prefix">Am 03.09.21 um 02:45 schrieb Yuxin
Zhou:<br>
</div>
<blockquote type="cite"
cite="mid:CAD0KDxrJnkey2rRtmkWzNGKjoH54EoiVFymA5arT0upwsKLY+A@mail.gmail.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<div dir="ltr">Hi Spencer,
<div>Thanks for the reply. I tested out two of your ideas. After
hosing for one year, I first let the AMOC recover for 100
years. Oxygen basically remained the same. Then I hosed with
5Sv of freshwater for ten years. AMOC is basically gone at
this point:</div>
<div><img src="cid:part1.A4236CE8.E6F99D28@awi.de"
alt="image.png" class="" width="461" height="250"><br>
</div>
<div><br>
</div>
<div>However, oxygen still didn't change much:</div>
<div><img src="cid:part2.159EBFB0.E641C976@awi.de"
alt="image.png" class="" width="450" height="239"><br>
</div>
<div><br>
</div>
<div>Going forward, I might test out the different advection
schemes and other ptracer parameters to see if that helps.
Again, I appreciate your help.</div>
<div><br>
</div>
<div>Best,</div>
<div>Yuxin</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Sep 1, 2021 at 10:29
PM Spencer Jones <<a href="mailto:spencerjones@tamu.edu"
moz-do-not-send="true">spencerjones@tamu.edu</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Dear Yuxin,
<div>It seems to me that maybe you just didn't run for long
enough to see any change in the oxygen concentration. From
your email it seems like you only ran for 1 year. Is that
right? I wouldn't expect the oxygen concentration to
change until several years (maybe even decades) after
hosing has taken place, and only to change if the
reduction in the AMOC continues (i.e. you might want to
continue hosing, rather than switching it off). </div>
<div><br>
</div>
<div>I'm not sure why tutorial_global_oce_biogeo doesn't
match with observations, but usually the tutorial
experiments are set up to demonstrate the model
functionality, not to provide a very realistic simulation.
You might need to put more work into improving the forcing
fields and/or resolution in order to get realistic
output. </div>
<div>Good luck , </div>
<div>Spencer</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Aug 31, 2021 at
9:28 PM Yuxin Zhou <<a
href="mailto:yzhou@ldeo.columbia.edu" target="_blank"
moz-do-not-send="true">yzhou@ldeo.columbia.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Hi all,
<div>I'm running the tutorial_global_oce_biogeo
experiment and analyzing the oxygen results and I
found some weird behaviors. Any help would be
appreciated.</div>
<div><br>
</div>
<div>Here is the AMOC stream function in equilibrium,
which looks normal:</div>
<div><img src="cid:part5.70FFB237.EF328D4C@awi.de"
alt="image.png" class="" width="461" height="250"><br>
<div><br>
</div>
<div>Here is the AMOC stream function after a hosing
of 5 Sv for one year (by increasing precipitation in
the 50-70N North Atlantic region), which looks
normal too. It shows a weakened NADW:</div>
<div><img src="cid:part6.91CDF9B9.721363C6@awi.de"
alt="image.png" class="" width="461" height="250"><br>
</div>
<div><br>
</div>
<div>Here is the oxygen concentration of the AMOC
cross-section in equilibrium:</div>
<div><img src="cid:part7.14E16667.FAFC5B41@awi.de"
alt="image.png" class="" width="450" height="239"><br>
</div>
<div><br>
</div>
<div>Here is the oxygen concentration after the
hosing:</div>
<div><img src="cid:part8.A2E09BED.EF52F9B1@awi.de"
alt="image.png" class="" width="450" height="239"><br>
</div>
<div><br>
</div>
<div>Firstly, the oxygen concentration of the AMOC in
equilibrium does not reflect modern observations
such as the World Ocean Atlas, which shows
oxygenated water closely following the presence of
the NADW. Secondly, oxygen basically doesn't change
even though circulation changed dramatically. It
seems convection processes barely impact oxygen at
all.</div>
<div><br>
</div>
<div>Has anyone else seen this behavior? Any
suggestions for tests I can run to figure out what's
wrong?</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Yuxin</div>
-- <br>
<div dir="ltr">
<div dir="ltr">Yuxin Zhou
<div><a
href="https://urldefense.com/v3/__https://www.ldeo.columbia.edu/*yzhou/__;fg!!KwNVnqRv!XGV-_ZoSHtQ8Iafno1yNILLkNCN6MaDMwIwpWla_Ftn5cl116QSs05k-WzMaoC6wDGs$"
target="_blank" moz-do-not-send="true">https://www.ldeo.columbia.edu/~yzhou/</a><br>
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<br clear="all">
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</div>
-- <br>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">Yuxin Zhou
<div><a href="https://www.ldeo.columbia.edu/~yzhou/"
target="_blank" moz-do-not-send="true">https://www.ldeo.columbia.edu/~yzhou/</a><br>
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<pre class="moz-signature" cols="72">--
Christoph Voelker
Alfred Wegener Institute
Helmholtz Centre for Polar and Marine Research
Am Handelshafen 12
27570 Bremerhaven, Germany
e: <a class="moz-txt-link-abbreviated" href="mailto:Christoph.Voelker@awi.de">Christoph.Voelker@awi.de</a>
t: +49 471 4831 1848</pre>
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