## Where does WRF calculate velocity?

### Where does WRF calculate velocity?

Hi,

I am trying to find the part of the code where WRF updates the velocity u and v (or ru and rv). In particular I want to know exactly how rv is calculated from rv_tend. I assumed it was in rk_tendency but can't find where the 4D variables are actually updated at the end of the timestep.

Any help much appreciated!
emilyp

Posts: 10
Joined: Tue Apr 12, 2016 9:14 am

### Re: Where does WRF calculate velocity?

Hi,

The main code is in WRFV3/dyn_em/module_em.F

This is the place where ru_tend is updated in the above file.

# line number around 810

Code: Select all
`DO j = jts,MIN(jte,jde-1)   DO k = kts,kte-1    DO i = its,ite      ! multiply by my to uncouple u      IF(rk_step == 1)ru_tendf(i,k,j) = ru_tendf(i,k,j) +  u_save(i,k,j)*msfuy(i,j)      ! divide by my to couple u      ru_tend(i,k,j) = ru_tend(i,k,j) + ru_tendf(i,k,j)/msfuy(i,j)    ENDDO   ENDDO ENDDO`

Then, it goes into module_big_step_utilities_em.F file for actually calculating the velocities. Search for rv(i,k,j) inside the file.

HTH
Sudheer
--
Sudheer
Ph.D. Candidate
Univ of Texas
San Antonio, USA
sudheer717

Posts: 8
Joined: Mon Jan 18, 2016 8:46 pm