Vertical Eddy Viscocity for MYJ Model

[MirkoDHP]

Hello everyone,

I'm trying to obtain the vertical eddy viscosity to calculate turbulent fluxes (w'u' = -Km du/dz or w'v' = -Km dv/dz ), however, I'm failing to obtain Km or the eddy viscosity to calculate the fluxes.

I have been reading the forum and I found some threads related to this topic (such as T1, T2, or T3), but I haven't found a straightforward solution for MYJ in those threads. Looking at the module_bl_myjpbl.F, it is clear that MYJ does not output EXCH_M (only EXCH_H which is for heat).

I have edited the Registry.EM to obtain different variables such as EXCH_M, XKMV, or XKHV, but all of them are zero. The only ones that are not zero are EXCH_H, XKMH, and XKHH (the last two are horizontal eddy viscosities). I think XKHV should be equal to EXCH_H, but I'm still missing EXCH_M.

I know that one solution is to edit the MYJ module to output EXCH_M as it does with EXCH_H. However, I have to create many variables in order to perform this calculation, which for me is strange because I have seen many publications where they use MYJ and they plot the turbulent fluxes. Most of them, don't mention that they edited the codes.

Am I doing something wrong? Is there any solution to obtain Km or EXCH_M with MYJ? This is the namelist that I'm using (My simulation is only until 1km resolution, I understand for values lower than that I have to avoid PBL schemes):

&domains
 /

 &physics
 ...
 sf_sfclay_physics                   = 2,     2,     2, 2,2,2,
 sf_surface_physics                  = 2,     2,     2, 2, 2,2,
 bl_pbl_physics                      = 2,     2,     2, 2, 2,2,
 bldt                                = 0,     0,     0, 0, 0,0,
 ...
 sf_urban_physics                    = 0,     0,     0, 0,0,0,
 maxiens                             = 1,
 maxens                              = 3,
 maxens2                             = 3,
 maxens3                             = 16,
 ensdim                              = 144,
 sst_update                          = 1,
 /

 &fdda
 /

 &dynamics
...
 /

 &bdy_control
...
 /

 &grib2
 /

 &namelist_quilt
 nio_tasks_per_group = 0,
 nio_groups = 1,
 /

Thank you everyone in advance,

 

[Ming Chen]

Hi,

exch_m is a diagnostic variable for momentum. It is not used outside the scheme

exch_m can be calculated with this line


EXCH_M(I,K+1,J)=AKMK(KFLIP)*DELTAZ

You can find this line in the myjurb and qnsepbl schemes that are based on MYJ

 

[MirkoDHP]

Hi,

exch_m is a diagnostic variable for momentum. It is not used outside the scheme

exch_m can be calculated with this line


EXCH_M(I,K+1,J)=AKMK(KFLIP)*DELTAZ

You can find this line in the myjurb and qnsepbl schemes that are based on MYJ

Thank you for your help , I really appreciate it.

I will edit the module_bl_myjpbl.F with that line. One question, I was testing WRF3.9.1.1, and in that version (as in WRFV4.4.1), EXCH_H is defined as EXCH_H(I,K,J)=AKHK(KFLIP)*DELTAZ, but I just noticed that in WRFV3.4.1 EXCH_H is defined as EXCH_H(I,K+1,J)=AKHK(KFLIP)*DELTAZ (similar to the line that you just provided). Is this something that I should take care or it is just a change in the notation of the vertical levels between versions?

Also ( and I don't know if this is correct) do I have to add EXCH_M for the subroutine MYJPBLINIT like this? Is this necessary?:

      SUBROUTINE MYJPBLINIT(RUBLTEN,RVBLTEN,RTHBLTEN,RQVBLTEN,          &
     &                      TKE_MYJ,EXCH_H,RESTART,ALLOWED_TO_READ,     &
     &                      IDS,IDE,JDS,JDE,KDS,KDE,                    &
     &                      IMS,IME,JMS,JME,KMS,KME,                    &
     &                      ITS,ITE,JTS,JTE,KTS,KTE                 )
!-----------------------------------------------------------------------
      IMPLICIT NONE
!-----------------------------------------------------------------------
      LOGICAL,INTENT(IN) :: ALLOWED_TO_READ,RESTART
      INTEGER,INTENT(IN) :: IDS,IDE,JDS,JDE,KDS,KDE,                    &
     &                      IMS,IME,JMS,JME,KMS,KME,                    &
     &                      ITS,ITE,JTS,JTE,KTS,KTE

      REAL,DIMENSION(IMS:IME,KMS:KME,JMS:JME),INTENT(OUT) ::    EXCH_H, &
     &                                                         RUBLTEN, &
     &                                                         RVBLTEN, &
     &                                                        RTHBLTEN, &
     &                                                        RQVBLTEN, &
     &                                                         TKE_MYJ, &
                                                                 EXCH_M
      INTEGER :: I,J,K,ITF,JTF,KTF
!-----------------------------------------------------------------------
!-----------------------------------------------------------------------

      JTF=MIN0(JTE,JDE-1)
      KTF=MIN0(KTE,KDE-1)
      ITF=MIN0(ITE,IDE-1)

      IF(.NOT.RESTART)THEN
        DO J=JTS,JTF
        DO K=KTS,KTF
        DO I=ITS,ITF
          TKE_MYJ(I,K,J)=EPSQ2
          RUBLTEN(I,K,J)=0.
          RVBLTEN(I,K,J)=0.
          RTHBLTEN(I,K,J)=0.
          RQVBLTEN(I,K,J)=0.
          EXCH_H(I,K,J)=0.
          EXCH_M(I,K,J)=0.
        ENDDO
        ENDDO
        ENDDO
      ENDIF

      END SUBROUTINE MYJPBLINIT

Thank you!

 

[Ming Chen]

please follow the formula in the version you used. Since WRFv4.0, the vertical coordinate is changed, which affects some codes. Personally I won't recommend mixing codes from different versions.