mixed layer problem

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tony1230
Posts: 87
Joined: Wed Mar 31, 2010 3:29 pm
Location: SKLEC,ECNU,Shanghai,China

mixed layer problem

#1 Post by tony1230 » Sat Jul 19, 2014 2:35 pm

Hi ROMS's friend

I am running a real case with biological processes and want to know if the surface/bottom mix layer depth is variable due to seasonal cycles in air-temp ans short wave radiation, etc. The model spin-up from the steady state at Aug 1,2008. In my area of interest, surface waters begin to form the surface thermocline in May, reaching its strongest state in Jul-Aug, and to disaggregate in mid Sep.

I plot the temperature time series of a station in area we thought to be most clear to depict the forming-destroying life of thermocline. But in my model output, the thermoclines kept living for ca. half month (near the 60 steps in the figure attached), then the upper layers temperature were pulled down abruptly and the thermoclines almost disappear. As was mentioned, the surface mixing layer was broken up at mid Sep in this area and it should also has a gradually weakened life time. I have been checked many times for temp related variables, advection schems and etc, but all failed.

I need help from any of you to guide me out of this problem. Thank you in advance.

-Shou
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Temperature profile time series at a fixed station
Temperature profile time series at a fixed station

lanerolle
Posts: 157
Joined: Mon Apr 28, 2003 5:12 pm
Location: NOAA

Re: mixed layer problem

#2 Post by lanerolle » Sun Jul 20, 2014 1:34 am

1. What is the depth of the station you have plotted the time-series for?

2. Have you tried different ROMS vertical eddy-viscosity models (especially GLS k-omega, k-kl)?

3. During September, did you have extreme meteorological conditions (e.g. strong winds) which induced heavy vertical mixing? I am assuming that you are using the ROMS bulk flux formulation.

4. For this location in consideration, do you need to take into account light penetration effects - i.e. a Jerlov water type other than 1? Is the water always clear at this location throughout the whole year?

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