[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Alk

We should be aware that experimentalists deliver Big Delta 14C:
Delta14C = delta14C - 2delta13C +someoddconstant.
from delta13C in the Ocean we deduce a contribution of 4 permil to delta14C.
The more severe fact that POC with about -100 in delt13C is brought to
depth will not be elucidated from look at 13C. In my experience it is
a small effect (compare (1 GtC/y)/(2mol/m**3) with 40 Sv of deep upwelling)
and it is additionally compensated by that fact that with biology we have
10% more carbon in the sea at given alk and pCO2.
"effect " means for Delta14C.

restoring alkalinity seems to be essentially ingomogeneous throughout
the group. Some of us have tracer advection which includes concentration/
dilution by evaporation/precipitation. Me for instance . If I take an
artificial tracer with homogeneous concentration 35 it will evolve
after some thousand of years to a salinity field. Anne and Ken were 
initially confused by this behaviour. correspondingly are DIC and alk
modified at the surface.

Other advection schemes (or models) hold the tracer at constant 35.
If they would treat alk without biology , alk should come out homogeneously.
My suggestion is:
everybody takes the type of alk he would get if the model would run
Was it Corinne who pointed out some years ago that a mixing of hypothetical
boundary conditions results in rather strange pCO2 fields?