[ecco-support] ECCO Mixed Layer Depths criteria

[Martha Buckley]

One follow up question regarding mixed layer depths in ECCO.

What is the criteria for the variable "MXLDEPTH" in the ecco v4 product.  I
think I recall being told it is the density equivalent of 0.8C.  Two
questions:
(1) Is this the criteria that was used?  It the criteria applied to model
profiles at the model timestep?
(2) If so, isn't this criteria a bit large?  0.125 kg/m^3 or 0.5C seem
common MLD criteria when applying criteria to monthly-averaged data.
However, criteria that are smaller (~0.03 kg/m^3 or ~0.2 C) are typically
applied when using raw observational profiles.

I know that the MLD criteria is somewhat arbitrary, but I want an idea of
the rational for the chosen criteria.
Thanks!
Martha


On Fri, Apr 28, 2017 at 6:04 PM, HONG ZHANG <hong.zhang at ucla.edu> wrote:

>
>
>
> -------- Forwarded Message --------
> Subject: Re: [ecco-support] ECCO2 Mixed Layer Depths Concerns
> Date: Fri, 28 Apr 2017 12:48:59 -0700
> From: HONG ZHANG <hong.zhang at ucla.edu> <hong.zhang at ucla.edu>
> To: Dimitris Menemenlis <dmenemenlis at gmail.com> <dmenemenlis at gmail.com>,
> Moisan, John R. (WFF-610W) <john.r.moisan at nasa.gov>
> <john.r.moisan at nasa.gov>
> CC: Daria Halkides <halkides at esr.org> <halkides at esr.org>
>
> On 4/28/17 9:37 AM, Dimitris Menemenlis wrote:
>
> Daria or Hong, would you have looked at MXLDEPTH depth in the “cube92”
> solution?
> ftp://ecco2.jpl.nasa.gov/data1/cube/cube92/lat_lon/
> quart_90S_90N/MXLDEPTH.nc/
>
> John, why not use the ECCO-V4, which is data-constrained?
> http://www.ecco-group.org/products.htm
> ECCO v4 is on a 1-degree grid, which is closer to your desired 2x2 degree
> grid.
>
> Dimitris Menemenlis
>
> On Apr 26, 2017, at 9:41 AM, Moisan, John R. (WFF-610W) <
> john.r.moisan at nasa.gov> wrote:
>
> Hello ECCO2’ers,
>
> I would like to make use of the Mixed-Layer Depth model outputs from the
> global model runs 1992-present (Nov. 2016) to drive some simple 1D
> biogeochemical models for CDOM.  I have binned to model outputs from the
> jpg site into monthly 2x2 deg. grids.  One thing of concern that I have is
> the trends in the global MLDs (see attached figure), which are more extreme
> in the SO.  Is there an issue with maintaining correct ocean boundary
> layers, esp. in the SO for this model?  Has this been observed yet?
>
> Hi John,
> You're right, MLD from cube92 run has bias in late stage
> because it's a free run for the later period.
> As Dimitris said, you can look at other ECCO product provided at the
> website.
> Please see attached fig showing MLD from ECCOv4 and ECCO llc270 for an
> example,
> where red line is for ECCOv4 (1992-2012) and blue line for ECCO llc270
> (2001-2015) in upper plot
> also MLD for cube92 is also shown in lower plot for reference.
>
> cheers
> Hong
>
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>


-- 
Martha W. Buckley
marthabuckley at gmail.com
http://sites.google.com/site/marthabuckley/home
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