[ecco-support] [EXTERNAL] ECCO bottom temperature bias in the Weddell Sea

[Dimitris Menemenlis]

Another answer contributed by Michael Schodlok:

> Hi Dimitris,
>  
> I would expect ECCOv4 to be too warm.
>  
> 1. Tore Hattermann from AWI (and now in Norway), showed at a FRISP meeting a couple of years
> ago, that there are problems in the southern/western (inner) Weddell Sea, if you don’t have the
> right properties at the Weddell Sea inflow location known as Kapp Norvegia (KN),
> (which is located approx. -13W, -71.5S.)
> As far as I remember he used CTD and Seal data to show the different states of the inner Weddell Sea
> and one point was a warmer state in the western Weddell Sea, if properties near KN are not well
> represented.
> ECCOv4 should have at least the seal data, but am not sure how much weight they put on it.
> But it looks that water masses are too warm in that location and that progresses towards the west.
>  
> 2. it also looks like the old BBL problem and/or getting bottom water, that hopefully ECCOv4 produces, on
>  the southern Weddell Sea Continental shelf towards the north, and down into the abyss.
> because of the representation of the continental shelf at  that horizontal grid spacing
> because of the vertical grid levels and hence artificial numerical mixing (unless that is taken
> care of by the adjoint)
>  
> So, I don’t know:
> how many data points are available in the western Weddell Sea?
>   how much weight does ECCOv4 places on the available data?
>    how well is the deep and bottom water mass production represented?
>    Where does the DW/BW that is produced end up -  abyss? or above?
>    Does ECCOv4 have a BBL scheme? Does it need one?
>    How does ECCOv4 represent downslope flowing water masses?
>    Just a few questions.
>  
>  Cheers
>  Michael


> On Jun 12, 2020, at 8:45 PM, Shanice T Bailey <stb2145 at columbia.edu> wrote:
> 
> Hi ECCO Consortium,
> 
> My name is Shanice Bailey. I am an Earth & Environmental Science graduate student at Columbia University advised by Ryan Abernathey. I've compared averaged bottom temperatures within the Weddell Sea region from ECCO's dataset, as well as from the World Ocean Atlas 2018 datasets for two separate time periods (1981-2010 and 2005-2017). Below I have attached a figure of ECCO and WOA's bottom temperature spatial distribution as well as their difference. From the figure you can see that ECCO is overall warmer than the observational dataset. I am emailing to ask if you may know the reason why ECCO is representing a 0.5-2˚C warmer temperature bias. I still consider myself a novice user of ECCO so I was hoping you may shed some light on this. I would appreciate any insight, and thank you for your time.
> 
> 
> Best,
> 
> Shanice T. Bailey
> 
> 
> [The attachment bottom-temperatures.png has been manually removed]
> 
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