Custom Query (964 matches)

I added several new palettes to the plotting package based on the vivid colormap from ​Matlab Central.

This palette is good for salinity (vivid1_128.pal):

and free-surface (vivid2_128.pal)

The above palettes are still linear.

A bug was corrected in t3dbc_im.F when computing the passive/active boundary conditions for tracers. In the western boundary we need to have:

                IF (LBC(iwest,isTvar(itrc),ng)%nudging) THEN
                  IF ((dTdt*dTdx).lt.0.0_r8) THEN
                    tau=Tobc_in(itrc,ng,iwest)
                  ELSE
                    tau=Tobc_out(itrc,ng,iwest)
                  END IF
                  tau=tau*dt(ng)
                END IF

instead of

                IF (LBC(iwest,isTvar(itrc),ng)%nudging) THEN
                  tau=Tobc_out(itrc,ng,iwest)
                  IF ((dTdt*dTdx).lt.0.0_r8) THEN
                    tau=Tobc_in(itrc,ng,iwest)
                  ELSE
                    tau=tau*dt(ng)
                  END IF
                END IF

Similar corrections are done for the eastern, southern, and northern boundaries.

This error implies that the inflow tracer values are not nudged as strongly as we thought by a factor of dt in days. In some applications with long time scales, this bug is not that significant. However, it effects are more noticeable when the nudging scales are comparable with the length of a single time-step (dt).

Once corrected, you will not be able to reproduce previous solutions unless that you increase the nudging time scale, tnudg(itrc), by a factor of dt in days (dt/86400). The change in that nudging scale may not be that significant and you get the save tracer behavior at the boundary.

Similar boundary conditions for other model state variables were correct.

Many thanks to Tingting ZU for ​bringing this to my attention!

Added the option to have spatially varying Jerlov water types for light absorption in the water column. This is used when SOLAR_SOURCE or LMD_SKPP CPP options are activated.

A new CPP option WTYPE_GRID is introduced to activate spatially varying Jerlov water types. The ROMS internal variable Jwtype is now a floating-point variable to facilitate I/O manipulation within the metadata model. The spatially varying Jerlov water type index can be specified in two ways:

• A variable, wtype_grid, in the ROMS GRID NetCDF file:

          double wtype_grid(eta_rho, xi_rho) ;
                  wtype_grid:long_name = "Jerlov water type index" ;
                  wtype_grid:coordinates = "lon_rho lat_rho" ;
  

• or an analytical function in new routine ana_wtype.h, which can be activated with new CPP option ANA_WTYPE. For example, we can have an expression to set the Jerlov water type index in terms of the bathymetry to give a distribution of values between 5 (shallow; turbid water) and 1 (deep; clear water):

        fac=1.0/1000.0_r8                   ! Inverse bathymetry threshold
        DO j=JstrT,JendT
          DO i=IstrT,IendT
            Jwtype(i,j)=ANINT(5.0_r8-4.5_r8*(TANH(h(i,j)*fac)))      ! 1:5
          END DO
        END DO
  

The variable Jwtype is used in lmd_swfrac to compute the fraction of shortwave flux penetrating the water column (light absorption), modeled as a double exponential decay function in Jerlov water type. The double exponential parameters (lmd_mu1, lmd_mu2, lmd_r1) were also enhanced to add additional Jerlov coastal water types: 1, 3, 5, 7. Currently, the following Jerlow water types are supported:

   Array     Jerlov
   Index   Water Type   Examples
   -----   ----------   --------

     1         I        Open Pacific
     2         IA       Eastern Mediterranean, Indian Ocean
     3         IB       Western Mediterranean, Open Atlantic
     4         II       Coastal waters, Azores
     5         III      Coastal waters, North Sea
     6         1        Skagerrak Strait
     7         3        Baltic
     8         5        Black Sea
     9         7        Coastal waters, dark

The range of indices 1:9 are ordered by increasing absorption: from clear water (type I) to dark turbidity water (type 7). The indices correspond to the paramenters (lmd_mu1, lmd_mu2, lmd_r1) used to model the light absorption into the water column using a double exponential fitting function of (Paulson and Simpson, 1997).

The following figure shows the Jerlov's water type classification based on transmittance along 1 m of seawater:

The water type 9 was not included in the above array classification indices because its double exponential fitting parameters are not available.

I also introduced routine ana_dqdsst.h to specify the surface net heat flux sentivity to SST, d(Q)/d(SST), with analytical expressions (internal ROMS variable dqdt). This is activated with new CPP option ANA_DQDSST. It is now possible to specify the SST in a NetCDF forcing file and the d(Q)/d(SST) field with an analytical function. No longer we need both variables in the NetCDF file.

I haven't coded the function that computes d(Q)/d(SST) using the formula reported in Barnier et al. (1995). Several additional atmospheric field are required (see their equation 6b). The values for d(Q)/d(SST) can be negative or positive and has units of Watts meters-2 Celsius-1 (or internal kinematic units of m/s/Celsius).

If you are planning to use QCORRECTION in your application, I suggest you to read Barnier et al. (1995) paper first. There are some messages in the forum suggesting the summer warming trends cannot be fixed with QCORRECTION. I just tried in the Gulf of Mexico and it worked well. It is just a matter how you specify the appropriate d(Q)/d(SST) values. I usually use monthly composite SST from the NOAA CoastWatch OpenDAP catalog (​http://oceanwatch.pfeg.noaa.gov/thredds/catalog.html), see product SST, Blended, Global, EXPERIMENTAL (BA/ssta/mday).

Reference:

Barnier, B., L. Siefridt, and P. Marchesiello, 1995: Thermal forcing for a global ocean circulation model using a three-year climatology of ECMWF analyses, J. Marine Systems, 6, 363-380.