meaning of fields in wrfrst files, V4

Hello,

I have two questions. I'm running WRF V4.

I want to run a small WRF ensemble with different initial conditions. To do so I need to perturb some fields in the wrfrst* file (temperature, winds, specific humidity, pressure).

But when I look at the restart file, I see that there is a U_1 and U_2 variable (same as V_1, V_2, W_1.... and more). When I look at these in ncview they appear to be indentical.

Can anyone enlighten me about what the meaning of the _1 and _2 version of the variables is?

Thanks

Var_1 and Var_2 are inherited from older versions of WRF. They used to represent Var in the previous and current time step. In newer version of WRF, restart run only needs the variable in current time step, i.e., Var_2. You can ignore Var_1.

Wonderful, thanks for the quick reply!