High Temperature in Summer

[taowangouc]

Hi everyone!

I am implementing a model in the Bohai sea, which has 1500 m horizontal resolution and 20 vertical sigma levels.
However,I have some problems with my model.
My roms result of water temperature in summer is much higher by compare with the Multi-scale Ultra-high Resolution (MUR) SST Analysis and observation results.
Moreover, the temperature in the central sea area has a trend of increasing year by year.

The comparison of the sea surface temperature in August is shown below.


Sea surface temperature in August from the ROMS model simulation in the first year

Sea surface temperature in August from the ROMS model simulation in the second year

Sea surface temperature in August from Multi-scale Ultra-high Resolution (MUR) SST Analysis

The model’s sea surface forcing is obtained from ERA5 (using the bulk formulae).
Model’s lateral open boundary conditions are interpolated from the hourly output of a Nemo model in the Yellow sea and Bohai sea.

Activated C-preprocessing Options:

Code: Select all

#define ROMS_MODEL
#define UV_ADV
#define UV_COR
#define UV_VIS2
#define MIX_S_UV
#define UV_QDRAG 

#define TS_MPDATA
#define DJ_GRADPS
#define TS_DIF2
#define MIX_S_TS
#define SALINITY
#define MASKING
#define SOLVE3D
#define CURVGRID
#define NONLIN_EOS

#define AVERAGES
#define RADIATION_2D     

# define BULK_FLUXES 
# define EMINUSP    
# define ATM_PRESS  
# define SOLAR_SOURCE 
!# define LONGWAVE_OUT
!# define LONGWAVE

#define LMD_MIXING
#define LMD_RIMIX
#define LMD_CONVEC
#define LMD_SKPP
#define LMD_BKPP
#define LMD_NONLOCAL
#define LMD_SHAPIRO
#define LMD_DDMIX

#define SSH_TIDES
#define UV_TIDES
# undef RAMP_TIDES  

#define ANA_BTFLUX
#define ANA_BSFLUX
!#define ANA_BPFLUX
#define MY_APPLICATION
!#define TS_VAR
!#define ANA_PASSIVE
!#define T_PASSIVE

I have checked the boundary file,it seems fine.
Does anyone have similar problems? Could anyone give some suggestions?
Thank you for your help in advance.

[hbzong]

Did you try to let the model calculate upward longwave radiation (define LONG_OUT)?

In Bohai Sea, WTYPE is also a sensitive parameter for temperature simulation in the summer season.

[taowangouc]

I tried running with the option LONGWAVE_OUT, and SST in summer was still high.

When WTYPE=1, the SST in the first year is acceptable, but the it increases year by year. Besides, the bottom layer temperature is also high.
The above results are when wtype = 5. The bottom temperature is better than WTYPE=1, but the problem of SST rising year by year still exists.

[wilkin]

Telling us only your CPP definitions is not much information to go on. There are a lot more details in the log file.

But what I notice is you have:

Code: Select all

#define TS_MPDATA
#define TS_DIF2
#define MIX_S_TS

MPDATA is already quite diffusive, so adding explicit horizontal mixing (especially if your coefficient is high for your grid resolution - you don't tell us what you've done there), and you have horizontal mixing along s-surfaces. Over sloping bathymetry this will induce quite a bit of vertical mixing. I suggest #define MIX_GEO_TS instead.

Check that you have the correct units in your ERA5 forcing files. If you are using the default varinfo.dat, pressure needs to be converted from Pascals to millibars. Make sure the calculation of relative humidity from dew point is correct, and that the result is expressed as a percentage.

[arango]

Also, you are using a very old version of ROMS. We no longer have CPP options for tracer advection. The tracer advection is selected in roms.in. There are more options for advection. You have the option to select one scheme for temperature and another scheme for salinity and positive-definite passive tracers.